Cowon O2 Review

o2 PC200089 main Cowon O2 Review

Here we have Cowon’s newest flash-memory based PMP which certainly evokes comparisons to a hypothetical “D3”, a successor of the Cowon D2 (at least in theory). It has the same basic design (yet bigger), a touch screen interface, and an SDHC slot. However, it’s certainly closer to the A2 or A3 considering its video capabilities.

The O2’s specs look absolutely amazing on paper – hardly any other portable player that comes close in supporting so many audio and video formats. On first glance it appears as if Cowon concentrated on the fundamentals, giving their customers a powerful device – an unrestricted video and audio player – that gets the basics right.

But we at anythingbutipod aren’t here to recite spec sheets or press releases. We rather check how the O2 performs in reality. Read on for the rather inconvenient truth…

  • Quick Look
  • Capacities: 8, 16, 32 GB Flash Memory + SDHC slot
  • Screen: 4.3“ 480 x 272 WQVGA TFT
  • Size: 119.5 x 73.4 x 18.0 mm
  • Weight: 205 g
  • Supported Video Containers: AVI, WMV, ASF, MP4, Matroska (MKV), OGM, MPG/MPEG, DAT, MTV
  • Supported Video Codecs: DivX 3.11/4/5/6, XviD, MPEG-4 SP/ASP, WMV 9/8/7, H.264, M-JPEG, MPEG 1
  • Supported Video Resolution: Max. 1280 x 720 px, 30 fps (720p)
  • Supported subtitles: SMI (Color Tag), SRT, SUB (Text Type), DivX Bitmap
  • Supported Audio Codecs: MP1/2/3, WMA, AC3, AAC, FLAC, OGG Vorbis, OGG FLAC, Apple Lossless (ALAC), True Audio, Monkey’s Audio (APE), MusePack (MPC), WavPack, G.726, PCM/WAV
  • Supported Audio Resolution: Max. 24bit, 96kHz
  • Sound Enhancements: BBE, M3B, MP, 3D Surround, 10-band pseudo-parametric EQ
  • Supported Image Formats: JPG, GIF, PNG, TIF, BMP, RAW
  • Transfer Mode: MSC
  • User Interface: Touch screen and tactile buttons
  • Other Features: SDHC slot, TV-out, mono speaker, SDK available (user created applications), text reader, image viewer, pitch compensation, voice recorder, timer/alarm, Korean-English dictionary (optional download)
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In the box we find an AC adapter that works internationally – 110-240V – and comes with exchangeable prongs for European and American outlets. Excellent decision, Cowon – this wall wart is a definite plus for travelers.

Without the AC adapter one couldn’t charge the O2 comfortably, at least not with the currently available firmwares which don’t support “proper” charging over USB. The huge flaw of the current O2 firmwares is that the screen never turns off (which of course is also very bad for a TFT display in the long run). It obviously consumes more power than it could charge over USB, draining the battery while it’s connected to a computer. Don’t be surprised if the O2 suddenly dies while transferring files over. At least there’s a hack-ish workaround available: switch the hold button before connecting, that way the O2 charges via USB – but it doesn’t show up connected to the computer. Charging over USB of course takes a lot longer than with the beefy 3000mAh AC adapter. Another thing to mention is that the O2 gets rather hot while charging. This seems to be the case with other DaVinci chip equipped PMPs as well.

The stock earbuds coming with the O2 aren’t bad. They have acceptable clarity and a decent amount of bass. Too bad they come with an awkward J-style cable, but all in all they should be sufficient as a backup pair of phones. Of course you might want to upgrade to some decent IEMs or headphones to get the most out of the O2.

Cowon invented yet another… “thing” that doubles as a stylus and a kickstand, similar to the D2’s awkward “triangle” thingamabob. It’s rather useless for both applications. As a kickstand it’s quite unsafe, the O2 topples over easily. As a stylus it’s tedious – too short, too fat. You’re supposed to attach it to the O2 with a small lanyard, so it swings around (and might even damage the screen when you stuff the player in your pocket). I assume these silly “cellphone charms” are popular in Asia, but I just find this thing to be obnoxious. It wouldn’t be too hard to make space for a stylus silo in the O2’s housing (like on the Nintendo DS or almost all PDAs available) and give the O2 a real, useful stylus instead. On the other hand, I’d be happy if the O2 interface would be optimized for finger-use, with larger icons and haptic gestures.

An USB cable is of course included, but Cowon skimped on the TV-out cable which has to be bought separately. At first I thought it’s a standard 4-pin 3.5mm-to-RCA cable as used by most camcorders and many PMPs, since that’s the logical way to implement the TV-out on a player like this. However on closer inspection Cowon messed the TV-out
up by using a proprietary USB-to-RCA cable design. A good thing the cable is rather inexpensive, but it should really be included by default.

Design & Build Quality

This player is more or less built like the proverbial tank, in typical Cowon quality. It’s rather heavy, and nothing creaks or bends. The whole O2 is plastic, but it’s of higher build quality than even some players with metal housing. Even if the back sounds a bit hollow when you tap on it, it still feels solid. The white and pink versions of the player have a glossy finish, the black one is matte. No superfluous design excesses, no blingy stuff, a real understated “form follows function” approach – which I personally appreciate a lot.

The USB port, SDHC card slot, and reset hole are hidden beneath a latch, similar to the one used on the Cowon D2. From my experience with the D2, this latch is anything but flimsy and should hold up well in the long run. The headphone jack is a bit too close to the latch, so it can’t be easily opened when a bigger headphone plug is connected.

I should also mention that USB transfer speeds are pretty good. Not as fast as some HDD-based players, but faster than many other flash-based ones.

One aggravating flaw in the hardware design of the O2 is the lack of tactile buttons, especially a much needed play/pause button. It only has two volume buttons (which can double as FFWD/REW buttons) and a slider for power and hold. This makes the O2 quite a hassle to use as an audio player on the go. Everybody complained already about the older D2 not having enough hardware buttons – but at least this player has a proper play/pause button.

Cowon, here’s a suggestion for you: make both volume buttons pressed together function as play/pause. That way the O2 would already become a way better audio player, not only on the go.


The O2’s 24bit 480×272 pixel screen is somewhat low-end by today’s standards. Many other players with comparable or even smaller screen sizes already have 800×480 pixel screens. This means those screens have three times the pixels, three times the clarity, three times the detail of the O2’s screen. Since the O2 (theoretically) plays 720p HD video, a higher pixel density and resolution would certainly be a wise choice. This however doesn’t mean the O2’s screen is really bad, but when you hold it close you do notice the dot-pitch and pixel grid, which can be a bit distracting when watching videos. I assume Cowon chose this particular screen model to keep the price of the player down. Still, a higher PPI count would have been great.

Speed is acceptable on the O2’s screen, the screen refresh is fast enough to not display too much unsightly ghosting with videos. Sure, it’s nothing like the 2ms response on my computer monitor, but it’s better than many other portable players’ screens in that aspect.

Viewing angles are more or less ok, the O2’s screen doesn’t solarize or invert the colors much when viewed from an angle. It’s certainly better than many other players in that aspect. However there’s a peculiar contrast “hump” around the view from center, when tilting the screen slightly up or down. Viewing the screen from the exact center gives the best contrast, but viewing from the sides works fine as well, it’s just a little washed out. Colors and brightness are good, I actually never use more than brightness level 3 (of 10), even in daylight.

Speaking of daylight: the O2’s screen is quite glossy and reflective. In bright surroundings the screen reflections can be bothersome. A good remedy is a non-glare screen protector – one of which should be applied in any case to protect the screen from scratches.

User Interface

This is the root of all evil. The user interface is a catastrophe, plain and simple. It’s like a textbook case of “How Not to Do It”, regarding usability and functionality. Almost everything is needlessly complicated or simply annoying.

I don’t even know where to start… Well, the first thing one notices is how unresponsive the touch screen is, and how sluggish and laggy button presses and scrolling behave. Sometimes you even see the button press reaction, the hover color, but nothing happens. The O2 runs a processor that’s a multitude faster than, say, my Palm PDA or Nintendo DS, yet I never have theses issues on other touch screen enabled devices. Cowon’s own D2 doesn’t have that lag and unresponsiveness either.

Icons and buttons are tiny, confusing, and generally difficult to use. The Cowon D2’s small 2.5” touch screen is quite pleasant to use nowadays (after two years worth of firmware updates), the O2’s large 4.3” screen is much, much worse. I refuse to use the silly “pseudo-stylus” that came with the O2; I want to use my grubby mitts. Make the interface finger friendly, for crying out loud. The screen is large enough and then some.

The screen you’re going to be using the most is quite botched. Of course I’m talking about the file browser – no matter if audio, video, or otherwise. It basically looks like Explorer on Windows 3.11, and it’s about as primitive. The only way to wade through file lists is by using the tiny scroll bar, which is as unresponsive and laggy as the rest of the interface. The O2’s screen is physically quite recessed in the outer frame of the housing, which makes it really hard to reach the scroll bar at the right side where the screen meets the enclosure. File lists don’t loop or repeat – when you want to reach the bottom of the current list you can’t simply go up one step, instead you have to manually scroll all the way to the bottom. There are no “virtual motion” gestures like on the D2, Samsung P2, or iPod Touch, you can’t just easily swipe anywhere on the screen to go up or down. It’s one huge hassle getting to the files you want. “Tedious” summarizes the file browser experience in one word. On the positive side, you can delete files and folders in the browser, and it’s a pretty fast operation compared to the rest of the interface.

There is also no proper “close” or “back” button for the file browser. If you for example just want to check files (but not select them) while listening to audio or watching video, you can’t go directly from the file browser back to the audio or video screen, you have to do a detour via the main menu and make your way from there to the screen you came from. Or you can use the “multitasking” icon which requires the same amount of taps. In any case, the button that would logically be considered as the “back” or “close” button actually leads you to another screen than were you came from. The button’s icon is an arrow pointing to the left “<--" for crying out loud, so I expect it to take me back, and not all around the place. For returning to the main menu there's already a button labeled "M" - having the same function on the "<--" button makes no sense. This is a serious logical flaw in the interface.

Let’s have a look at the aforementioned main screen. It’s the only screen that has properly sized icons to use with one’s fingers. Cowon however made it needlessly complicated with superfluous up/down/left/right scroll arrows. All the menu items would simply fit on one screen, just like on an iPod Touch, but the O2 doesn’t use the screen real estate efficiently at all. Instead of three rows of icons we only see one, and the scroll animation at screen change is choppy and poorly executed.

Of course it’s a matter of taste, but the overall color scheme of the user interface is rather awful in my opinion. Bright blue, green, and yellow are the main eyesores, on a white-ish background. “Unobtrusive” is not the description that comes to mind – less would be more, as far as the colors go. Background images are theoretically user-changeable, but only if they’re bright colored images. The O2 cannot change font colors, so any dark background image makes all text illegible. Instead of having a fancy SDK that just creates self-contained applets
besides the O2’s main system, I’d really rather have the option to tweak the system itself to improve the looks of the user interface.

The settings and option screens are generally well laid out, and every feature is fairly easy to configure. As for the inevitable comedy factor: all the option screens have a save button. This button is redundant and could be omitted – the settings are all saved automatically when you leave the options page anyway. Another thing I’m missing, coming from the D2 (and which is also available on the new S9) are slots to store several EQ and BBE presets. These preset slots come in really handy if you use different headphones, or listen to various kinds of music that require different equalization.

Another thing that annoys me greatly about the O2’s interface are several nonsensical popups. Popups usually are the last resort of unskilled interface designers when they don’t know how to implement functions properly. The biggest popup faux-pas is the one assigned to the power/hold slider button. I assigned the volume buttons to act as FFWD/REW in hold mode, and as regular volume buttons when hold isn’t engaged. Every time I slide a tiny bit too far from hold to normal mode I’m bothered by an obnoxious popup asking me if I want to turn the screen off or if I want to shut the whole O2 down. This is seriously distracting. The convention on Cowon players (and many other brands) has always been that a short slide means “screen off”, and a long slide means “power off”. I don’t need a patronizing popup asking me what I want to do; I know what I’m doing. A short slide always means screen off, a long slide always means power off. This popup is especially annoying when it’s interfering while I’m watching videos, and I really don’t want to be distracted by the badly designed user interface. Since the O2 doesn’t have enough tactile buttons I have no other choice as to slide between hold and normal to use both FFWD/REW and volume controls.

Other superfluous popups are the ones between video files. I really don’t need to know if the next file is loading, it only takes a few seconds anyways – no need to inform me about that. I trust the player to load the next movie, there’s no need to “shout”. The best interface is the one that’s invisible. Popups between videos kill the mood and have no use. The popup at connecting the O2 to a computer is another example. I really don’t need to decide if I want to connect the internal memory or the SD card to the computer. Both should connect at the same time, there are no excuses for bad firmware programming. More about that later, in the SDHC slot chapter. The list goes on – but I want to spare you, my valued reader.

Cowon has already spent time developing the UI for the D2. Much of the O2’s agony could have been saved by using what they have already created. I know the one player runs on Nucleus RTOS and the other one on Linux, but that is no excuse and should be no concern for the paying end-user. There is no reason to reinvent the wheel with the O2. The D2, X5, M3, or A2 worked well. The O2 is much worse, and I really don’t see why that is the case. To phrase it differently: Cowon, have your firmware programmers ever laid hands on a Creative player or an iPod? You could really learn a thing or two about usability from them.

Transferring Media / Software

This chapter is more or less a snooze-fest – and I mean this in a positive way. The O2 is a pure MSC (mass storage class) device, like any other USB hard disk or flash memory stick. It works on any modern operating system and shows up as a storage device in Windows Explorer, OS X Finder, Nautilus, Thunar, or whatever you prefer.

The O2 does not support the MTP protocol, meaning it is not compatible with any DRM-laden online music store. You have to rip your CDs on your own or use a non-DRM store, which probably gives you better audio quality and definitely more freedom anyway.

Cowon packs their JetAudio media manager application on the CD accompanying the O2, but I have not found out yet how to use this program efficiently – and I don’t intend to spend any more time on it. Best you stick with what you know: Winamp, Media Monkey, J.River, or whatever floats your boat. Or simply drag and drop your files over, which is my preferred modus operandi.


Let’s see which additional features Cowon packed onto the O2…

… or rather, let’s check first which features the O2 doesn’t have, compared to many other Cowon players. We find: no FM radio, no line-in or video recording, and no USB-On-The-Go. These features are perhaps not needed by the majority of users, and omitting them certainly helps keeping the price low. I personally could use line-in recording, but only if it was WAV or MP3. Seeing as most Cowon players use WMA recording nowadays due to lower licensing fees than MP3, I don’t feel too sad about the lack of this feature.

SDHC Expansion Slot

What we have is an SDHC slot which can be used to store music, movies, texts, images – anything the O2 understands. SDHC cards are currently available up to a size of 32GB, effectively doubling the O2′s capacity. You can even copy files between the SD card and the internal memory, making the O2 a decent image tank for your digital camera, as long as it uses SD cards as well. The downside to the SD slot is that it doesn’t integrate at all. You have to “connect” to the SD card when you want to access your data on there, which takes quite some time. The files on the internal memory and the card don’t merge at all. So you can’t listen to music in shuffle/random mode or watch videos from both memories at the same time. There has to be a better solution. Once again, the D2 had no such issues. But on the other hand, the D2 could not copy files between the two memories.

An utterly ridiculous annoyance about the SD slot is how it’s handled when connecting the O2 to a computer. You cannot connect both the internal memory and SD slot at the same time. You heard me right. At USB connect a popup appears that lets you choose which storage you want to connect, internal or SD. Are you kidding me? The D2, Sansa e200, Fuze, and other SD slot equipped players simply show up as two separate devices in Windows Explorer. That’s how it’s supposed to be.

Text Reader

The O2’s text reader is no substitute for a proper e-book reader; it only handles basic .txt files without formatting. It has some nice anti-aliased fonts, but it can’t be used in portrait orientation, only in landscape. Portrait would be much easier for reading in my opinion. You can choose between different combinations of background colors, half of them are useful and make the text legible without eye strain. The other half of color combinations is nonsense.

Fortunately you can drag anywhere on the screen to scroll through texts, you don’t have to use the tiny and hard to reach scroll bar at the right – unlike the O2’s tedious main file browser. Other haptic gestures that are sorely needed in the O2′s file browser (like left/right swipe for page up/down, or using the volume buttons for scrolling in hold mode) are implemented as well. It’s a shame these gestures are wasted on the text reader but not implemented where they are really needed on an everyday basis to improve the usability of the O2. Let’s hope Cowon expands these useful features to the main browser interface as well with future firmware updates. That alone would improve my opinion about the O2 quite a bit.

All in all the text reader is a quite laggy and unresponsive experience though, especially when you’re listening to music at the same time. Displaying text really can’t be such hard work for the O2’s powerful processor. Even my first Palm Pilot in 1997 did a better job as a text reader.

Sleuthing on Cowon’s Korean website I found a converter application called “mTrans” that gives support for a proprietary document format called CSD, which appears to be simi
lar to PDF. It supposedly lets you convert most common document formats to be used on the O2. However I couldn’t get mTrans to work on my computer, it failed to convert anything I tried (DOC, RTF, PDF, XLS, etc).

Image Viewer

The photo viewer is as well nothing more than “meh”. While it does support a respectable variety of image formats – including RAW photos by certain digital cameras – the actual rendering of the images is quite sub-par. It almost appears as if the O2 resamples all images (no matter what original size) to its 480×272 screen size, and when you try to zoom into the images you’re greeted by a blocky pixelated mess that looks like it was resized with a sub-par “Nearest Neighbor” algorithm instead of a better Bicubic or Lanczos one.

The most ridiculous part about the photo viewer is the error message “cannot rotate images while music is playing”. Here we have a device powered by an insanely beefy DaVinci chip, and it can’t rotate images while you listen to some tunes. I don’t remember the comparatively wimpy Telechips SoC in the Cowon D2 having any of these issues, be it blocky zoomed images or rotating issues while listening to music.

Cowon put some effort in bringing rudimentary “virtual motion” gestures to the image viewer as well, similar to the text reader mentioned above – but not to the file browser where it’s sorely needed on an everyday basis. While the file browser only reacts to the tiny scrollbar and icons, the image viewer at least lets you rotate images by simply drawing a circle on the screen. This is a good start for making the player a bit more intuitive and less hassle to use. However, other basic image viewer functions like dragging/panning are still badly implemented and tiring to use: instead of being able to simply drag a photo around with your fingers (like on the D2, AcidImage on PalmOS, Moonshell on the Nintendo DS, or similar) you have to use virtual buttons at the borders of the screen.

All in all the O2 might make a basic image tank and previewer for SD card based cameras, since you can copy the files over to the internal memory. For a full-fledged photo viewer it’s certainly lacking a lot in quality, though.


The O2’s mono speaker should work quite well for audiobooks, TV shows, and similar material where audio quality doesn’t matter much. With recent firmware updates (v1.17) the volume levels improved, making it useful for quiet surroundings. In loud environments you certainly won’t hear it. Since the speaker is on the back of the O2 it’s not in the optimal position for watching movies, but for audio you can simply turn it towards your listening position.

Voice Recorder

The voice recorder works well and gives quite clear results from close up and even from farther away sources. It can also be used with the O2’s timer function, starting a recording automatically (in case you’re on a secret spy mission or something like that).

On the other hand, the WMA file quality used by the voice recorder is more than insane, a complete overkill. It records in 128 or 192 kbps mono WMA, with a sample rate of 48 kHz (!). I’ve never seen something so beyond all reason. Where other voice recorders use 16, 32, or 64 kbps MP3/WMA, and a sample rate of 11 or 22.5 kHz (which is more than enough for voices), the O2 uses the mono equivalent of a more than 320 kbps stereo MP3 with DVD quality sample rate. It basically compares to watching a YouTube video on a 1080p HDTV screen.

The O2’s voice recordings are an utter waste of space, with no increase in quality over less ridiculous implementations as found in other products. No wonder the recorded WMA files are tagged by default with the artist field “O2 WMA Mania”… but in the end you get pretty clear voice recordings. I’m sure there are people out there who appreciate that, no matter the file sizes.


The aforementioned timer feature is very complex, letting you set up several tasks with daily, weekly, or specific date/time start points. You can choose between startup modes for video, audio, or voice recorder. The most amusing thing I noticed in the timer interface is a button labeled “channel” – which actually doesn’t have any function at all. You heard me right, it doesn’t do anything. Do I really need to go on about usability, intuitive interfaces, and whatnot?


Last but not least, instead of improving the interface usability or fixing bugs, annoyances, and inconsistencies regarding the main video and audio functions, Cowon recently started to spend firmware developer time and budget on bringing an SDK (self developer kit) to the masses. Sorry if I can’t be too excited about the SDK, but there are more important things to be fixed before we get a few Pong or Tetris clones.

Two sample applets come preloaded on the O2, a calculator and a notepad. The O2 runs an embedded Linux operating system, so it’s no wonder the SDK can only be used on Linux computers (or virtualized machines) as well. I’m no expert in programming languages, but to me it seems you have to have at least C++ hacking skills to make any use of it. It’s certainly nothing for the faint at heart, and Cowon’s documentation about the SDK is almost non-existent.


Sound quality of the O2 is very good, pretty much the same as most other Cowon players. It’s closer to the sound of the D2 than to the X5 or M3, meaning it’s a bit “colder/analytical” and not so “mellow” to my ears. Not that these nonsensical “audiophile” terms mean much – in any case, the O2 sounds just fine. In general I’d say it’s a tiny bit better sounding than the D2, yet very similar. There’s certainly nothing to complain about the O2’s audio signature. It has good stereo separation (“soundstage”), good signal-to-noise ratio, low harmonic distortion, and not as much bass roll-off with low-impedance phones as many other players. It might hiss a little with very sensitive low-impedance earphones, but I’ve heard worse.

However, unlike many other players you can’t really push the O2 to the maximum volume, level 50. It starts to distort slightly above volume 45, even with all enhancements and EQ off. The THD and SNR doesn’t go “though the roof”, but it’s too much to be comfortable. I’m not sure if this could be fixed by a firmware update, but in case you want to use a portable amplifier with the O2 it’s better to stay around 40 – 45 than going to maximum volume. This is according to my own RMAA tests with firmware v1.15.

Audio format and codec support on this player is nothing short of amazing. To the best of my knowledge only Rockbox supports more audio formats than the O2. Even MusePack and True Audio work, two formats where the expression “minimal distribution” actually is a euphemism. Whatever you throw at the O2, it will play it – except DRMed tracks, of course. Not to mention the capability of the O2’s DaVinci chip to decode state-of-the-art 24/96 audio. It might not be overly useful, but it doesn’t hurt either.

Like all other Cowon players, the O2 comes equipped with BBE audio enhancements, which in my opinion are the best sound tweaks available on portable players. They don’t sound too artificial and/or distorted, compared to sub-par enhancements like SRS WOW and similar. BBE Mach3Bass is a phase corrected and clipping protected bass enhancer that doesn’t make the sound muddy or veiled. It packs a really solid oomph, even with tiny earphones. MP Enhance gives some nice treble for headphones that need a little help. It’s a bit better (or at least more subtle) than mere EQing. The technical reason behind MP Enhance should be “restoration” of missing frequencies in lossy audio, but that doesn’t really work – so I see it as a nice treble booster.

The O2’s EQ is quite powerful with its pseudo-parametric 10-band design, and will probably alienate people that have no degree in audio engineering. With “pseudo-parametric” I mean that t
he center frequencies of each band cannot be adjusted freely, only three distinctive frequencies can be selected. Same goes for the Q-factor, where the options are narrow, normal, and wide. The absurd decision to split the EQ over two separate tabs in the options menu is no different to any of the other needlessly complicated approaches in the O2’s UI. First tab contains the EQ frequencies and presets, second tab contains the center frequencies and Q-factor notches. Of course this makes using the EQ quite a bit more confusing than necessary. Nevertheless, this is certainly a tool for advanced users and I’m sure such folks will appreciate the flexibility over a simple bass/treble or average 5-band graphic EQ solution.

One quite unique audio feature is pitch correction/compensation. To the best of my knowledge this was only ever implemented on one ancient Creative player before, but never seen again on any other DAP/PMP. Pitch correction of course means that you can speed up audio tracks without making voices sound like Alvin and the Chipmunks, or slow them down without getting a bad Barry White impersonation. I don’t see a real reason for pitch correcting music, but for spoken word material, voice memos, and similar it might come in handy. Pitch compensation can be turned off, leaving you with the usual speed control found on many other players as well – which is probably easier on the battery life.

The O2 lacks certain audio management features many people take for granted nowadays: it has no ID3 browsing, no support for playlists, and no traditional bookmarks. You can only search for music with the cumbersome file browser, and the only playlist you can create is a “favorites” list. This list however can only hold 300 files, which is certainly not enough to be useful for people used to “real” playlists. Don’t get me wrong, I love file browsing and detest ID3 browsing, but the O2 browser is just too tedious to use. One thing I like about the file browser is that it shows information about the currently highlighted file (codec, size, length, bitrate, sampling rate, etc). By the way, the positive aspect about having no ID3 browsing is that the O2 starts up quite fast, there’s no waiting for a database rebuild.

Audio book lovers, not all is lost, even though the O2 has no traditional bookmarks. The quite ingenious “recent files” list works well instead of bookmarks – and it’s completely automatic. It stores the last 50 files you opened, no matter if audio, video, or text, and also stores your progress inside them. Files you finished get deleted from the list automatically. This is in my opinion much better than regular bookmarks, since this system demands no user interaction at all – it just works. You just select a file from the list and continue where you left off. Kudos to Cowon. As much as I dislike many aspects of the user interface, this function is ingenious.

Now it’s time to look at the dealbreakers, showstoppers, and general annoyances. The lag and sluggishness of the user interface doesn’t have any respect for the audio part of the O2 as well. Changing tracks takes much longer than on any other player I know. You skip a track, you wait. Album art takes several seconds to load after a track started playing – and it looks terrible. Same as the photo viewer, the album art display uses a really bad resizing algorithm, making cover art look pixelated and blurry. Not to mention the images aren’t even centered in the background frame, making the display look quite amateurish, like a bad Winamp skin. ID3 tags and song titles don’t scroll on the playback screen, only the beginning letters of long track titles are shown. Fast forwarding and rewinding tracks is silent, contrary to all other Cowon players I tried. Not hearing sound bits while forwarding is annoying as you don’t hear where you’re actually at in a track. Here we go again with the comparisons: the D2 has no such issues, album art looks fine on it and loads fast, song titles scroll on the playback screen, FFWD/REW has sound.

The ultimate showstoppers however are the huge gaps, and the unbearable clicks between tracks. A large part of the audio community is constantly pleading for gapless playback (as seen on Rockbox, Zune, iPod, Trekstor Vibez, and Rio Karma so far) – but Cowon and most other manufacturers completely ignore that. It might be a cultural difference and maybe Koreans don’t listen to DJ mixes, concept albums, soundtracks, or similar – however the O2 is in that aspect the worst player I’ve ever used. Probably depending on the codec and encoding parameters, gaps can be up to three seconds in length, and are hardly ever shorter than one second. For me the real “what the heck?” moment however was when I started noticing distinctive loud clicks between tracks. It’s not between all tracks, but I’d say I hear it with more than 75% of all my music. It is severely irritating and kills the mood. Not to mention some tracks miss the first few microseconds at the beginning or at the end. It’s very noticeable when the first drum beat of a track is missing, for example.

Those are some of the most annoying flaws I ever heard, not even my $9.95 Chinese toy player has bugs like that. The O2 has all the makings of a seriously good audio player regarding its sound quality, codec support, EQ, and BBE enhancements – but I really can’t enjoy it with these aggravating flaws. Due to the lack of hardware buttons and tiny icons it can’t be a practical player on the go, but at least for stationary use it could work well once these firmware flaws are ironed out. Cowon, these bugs need to be fixed ASAP.


Time to take a look at the main rasion d’être of the O2: playing soaps and cartoons. Just kidding, the screen is big enough for blockbusters. Even if the aforementioned pixel density is not really up to date with modern players, and 480×272 is certainly not what a HD-capable player is all about.

On paper the O2 probably supports the biggest variety of video containers and codecs available on any portable player available. TCPMP and similar PDA/UMPC players excluded, of course. In reality it’s certainly different, since the O2 has severe issues playing back most 720p HD videos or MKV/h.264/x264 content, except ones encoded with the most basic settings. 720p might work fine when encoded with XviD or DivX, but the average WMV or MP4/h.264 720p trailers found on the internet all play so choppy that it’s impossible to watch them. h.264/x264 only works with simple profile, any advanced high profile settings like 8×8 transform or Trellis quantization result in stuttering and laggy performance, or no image at all – no matter if high-res or 320×240. Another issue with HD movies of course is the 4GB file limit of a FAT32 file system. You certainly can’t watch over-length movies in 720p anyways, since full movies would be larger than 4GB and would need exFAT/FAT64 or a similar modern file system to work without splitting them in parts. A FAT32 file system (as used on the O2) doesn’t support these file sizes.

In short, don’t get the O2 if all your videos are in HD or use some newer, more advanced codecs/containers. If you mainly watch regular MPEG4/XviD/DivX videos in an AVI container, the O2 will perform very well. Furthermore, video formats not supported by the O2 at all are (in order of personal preference): MPEG2/VOB, FLV, QuickTime/MOV, RM/RMVB. Too bad I can’t just put decrypted VOBs or a few YouTube videos on the O2. It might be either licensing fees or the MPAA that don’t approve of supporting these formats, who knows. It’s a shame since some Chinese no-name OEM players do support FLV and RMVB, but they are probably not exactly “legally” supported formats.

Subtitles work very well as far as I tested them, and most common formats are supported. Once again, another positive aspect where the O2 surpasses most other PMPs. Fancy modern formats like SSA/ASS don’t work of course, but basic SRT and SMI works just like on any decent computer media playe
r, like MPC or VLC. Plenty of useful additional subtitle features are implemented, like manual resyncing, choosing different subtitle tracks, font color/size, and so on.

As far as image adjustments are concerned, you can tweak aspect ratios (16:9, 4:3, auto), pan & scan (70 – 150%), and adjust the screen color temperature (RGB + contrast). Switching among multiple audio tracks is also supported, so you can enjoy some boring director’s comments on the go. Even screenshots can be taken, which are stored as uncompressed BMPs. Most features are really useful and work well; they certainly add value to the video player mode of the O2. My only gripe here is that the one feature I need the most (pan & scan) is the hardest to reach in the options list. It should be at the first (or last) position, not in the middle.

One feature that not many people would give a second glance is the possibility to switch the audio track from stereo to mono. It might appear negligible but has really saved some videos for me. I have quite a few TV-rips that have bad sound on one channel, or a weird left/right panning behavior that gives me headaches while watching/listening. Switching to mono is a lifesaver in that case and makes these bad videos a lot more enjoyable to watch.

Same as for the audio player and the text reader, recently played videos can be found in the “recent files” list, making traditional bookmarks obsolete. You can always resume where you left off, without worrying if you actually added a bookmark. Ingenious, as I already said before.

Now let’s look at the inevitable user interface screw-ups that are making your life harder during video playback. Usability flaws in general are the same already mentioned in the audio player and UI chapters of this review: not enough hardware buttons, tiny icons, unresponsive touch screen, laggy operation at times, and annoying file browser. No need to go over that again; on to the specific flaws of the video player…

First you will notice that you can’t skip videos. Yes, you heard me right. You can only fast-forward and rewind in a video, but you can’t easily skip to the next one. Imagine that behavior on your DVD player, in Windows Media Player, VLC, or wherever. You can’t imagine something as illogical as that? Well, you’re not alone. To get to the next video you have to go to the file browser, scroll around, and select it. Or you could “tap” to the end of the video with the touch screen controls, which isn’t any better. Not amusing. There’s also no folder advance, the O2 simply repeats all the videos in one folder but doesn’t go to the next. The boundaries you set for the O2’s audio player mode doesn’t apply to the video player, which is extremely annoying. “Pathetic” is actually the better word for these flaws.

However, even more annoying for me is that neither the BBE enhancements nor the EQ are available in video mode. Only some shabby “3D Stereo” effect is available, which doesn’t do any good. For crying out loud, I want Mach3Bass for my explosions and car chases, and BBE for making dull TV-rip audio quality a little more exciting. This is certainly a dealbreaker for me. Good thing at least the headphone amp (iBasso T4) I use with the O2 has a bass boost mode. The D2 (which I already might have mentioned once or twice in this review) does have EQ and BBE for videos, so there’s no excuse the O2 doesn’t. Cowon, this is another flaw that needs to be fixed – now.

Nobody can tell me there are any difficulties in implementing BBE/EQ for video. Why? Because video mode on the O2 has the same insanely processor intensive audio pitch correction mode as the music player. If you can pitch compensate videos, you can add some audio enhancements easily – which of course would be 100% more useful for most users.

Another thing that adds no value and just appears to be patronizing to me is the popup between videos. It tells that the next video is loading – well, thanks, I am aware of that. Instead of the popup it should just show a blank screen; the popup kills the mood when I watch several short clips in a row. There’s no need for that, my DVD player or any other device doesn’t do that either. I’ve already expressed my dislike for popups in the UI chapter above – and this one is certainly among the least useful and most distracting.

Cowon claims a battery life of 8 hours for video playback. I’m getting around 5 hours in reality, which is with non-HD XviD files and the screen brightness at 3/10 or lower. It’s not too shabby and certainly usable compared to some of the competition’s players, but I would have expected a little better from Cowon. Some people claim a battery life of 6 hours and more, but I cannot verify that.

I also have the optional TV-out cable, and it doesn’t really work that well on my TV. Image quality is almost decent, quite soft (yet watchable), but the borders are cut off. That’s a big problem with hard-subbed videos, for example. However, the main problem is that all 16:9 videos are displayed as squeezed 4:3 with wrong aspect. Good thing my TV can stretch the image to correct the aspect ratio, but that really shouldn’t happen. I’m sure that can be fixed via a firmware update – like almost everything else that plagues the O2 in its current state.


What can I say?

Yes, the O2 plays videos, there’s not much to complain about. It doesn’t play ever format as advertised, and it doesn’t give me the BBE sound enhancements I’m used to from Cowon – but it plays most videos well, except certain 720p HD, MKV, and/or h.264 material. The interface is clumsy, lacks refinement and usability. On the other hand, not having to convert most stuff and having decent subtitle support are a godsend, so that’s the main advantages of this player. It also has lots of intelligent features concerning image adjustments and subtitle tweaking. Not to mention it’s the only truly portable player that supports MKV containers so far (to the best of my knowledge). At least in theory, but certainly not in reality.

Yes, the O2 also plays audio – and it sounds good while doing so. It supports more formats than most other players available (besides Rockboxed ones) and the BBE sound enhancements are the crème de la crème, as far as portable audio goes. However the clicks between tracks and the huge gaps are quite the showstoppers for me. Not to mention the lack of tactile buttons and the tiny icons on screen, making the player a hassle to use, not only on the go. Album art is awful as well. It’s a shame the decent sound quality and amazing codec support is wasted by such avoidable flaws. Let’s hope Cowon fixes these grievances ASAP.

If you’re looking for a video player that performs well as far as basic playback is concerned and you don’t care about the interface (or have the stamina to wait for an upcoming decent firmware), you could give the O2 a try. At least it’s cheaper than, say, the new generation of Archos PMPs and supports a lot more formats. However, if you’re in for an audio player to use on the go, look at other devices. The O2 is certainly not optimal for this kind of usage.

With the currently available firmwares I definitely cannot recommend the O2 with a clear conscience.

I will make my final statements one long rant. Please skip the following if you want a neutral, unbiased point of view. For the positive aspects read the rest of the review. Well, maybe you have to read between the lines.

I’m fed up with Cowon’s terrible firmwares. The “final” firmwares are worse than what other companies would even consider “beta”. I’m a paying customer, not a beta tester for these products. How Cowon can allow releasing a player like the O2 to the public is a mystery to me. The entire firmware programming team needs a refresh. The O2 firmware is so bad, it needs to be re-designed from scratch. The programming team needs some usability and interface experts as well and some UI designers that aren’t colorblind. T
he old Cowon D2 and new S9 interface shows that Cowon can do it right; the O2 is a catastrophe in comparison.

Cowon needs to stop reinventing the wheel with every new player – you would have thought they have learned from previous and very similar players like the D2, A2, or A3. Lots of annoyances we find in the O2 were already fixed, or never even existed in previous Cowon players.

Fans of the O2 will certainly hate me for this review, but think about it this way: if Cowon reads my rant they might try to improve the usability and quality of their firmwares. They always build very capable hardware, and usually mess it up some way or other with their obnoxious firmwares, fobbing their customers off with tiny improvements over the course of months, or even years. I’m just trying to accelerate this process – and I want a solid firmware now, suited for the O2’s solid hardware. No superfluous trinkets (two calculators and a dictionary are more than enough), but real improvements of the core functions.

For me the O2 is the straw that broke the camel’s back, after having owned and loved four generations of Cowon iAudio players. I almost feel personally insulted by the shortsightedness and lack of talent in firmware programming, as far as the basic important factors of a portable media player are concerned. How can there be such a discrepancy between the hardware and the software, quality-wise? The O2 almost does it all, but it does almost nothing right.


  • Plays lots of video formats without converting, good subtitle support
  • Plays almost every audio format known to man
  • Good sound quality and BBE enhancements (for audio only)
  • Ingenious “recent files” list
  • File/folder browsing
  • UMS/MSC mass storage class, works on any operating system
  • Flash memory (no fragile hard disk), SDHC expansion slot
  • Solid build quality


  • Not enough hardware buttons
  • Needlessly complicated, unintuitive, flawed, ugly interface
  • Sometimes laggy and sluggish operation, unresponsive touch screen
  • No EQ or BBE/M3B enhancements in video mode
  • Clicks and huge gaps between audio tracks
  • 720p HD and MKV/h.264 support has lots of issues
  • Lowly 480×272 screen instead of today’s 800×480 standard
  • No ID3 browsing, no playlists
  • No SD card integration
  • USB charging and USB connection with SD card are seriously flawed


If you still consider getting the O2 after my review, Amazon usually has it for the lowest price sans taxes and free shipping.

Many thanks to our forum member Dalmane98 for sending me the TV-out cable.


swild on January 14, 2009 7:16 PM

Damnit! Why is it so hard for them to put something together that’s superior to the ipod touch? The touch is on its second generation, and the underdogs are still at the gate.I’ll buy non-ipod if their feature sets are close (ie. zvm), but it looks like I’ll have to wait even longer…

Djini on January 14, 2009 7:34 PM

ook.(Archos 5 and iPod touch looking smugly over, while mama X5 shields little baby S9′s innocent eyes from the non adulterated fail of this player)

Dalmane98 on January 14, 2009 7:46 PM

A Fair and Balanced Review…I really expected more from Cowon and was very disappointed with my O2…

kasrhp on January 14, 2009 7:55 PM

Thanks for the review. I have the o2, and I have a very love/hate relationship with it. I dont think there is another player that can even hang with this…if they fix the firmware issues. You did a good, brutally honest review. Thanks

Martin Sägmüller on January 14, 2009 8:03 PM

Kashrp (and all you other guys so far), thanks for your reply. I feel the same as you – I love that I can just drop some videos over without converting, but that’s about the only saving grace for the O2… I hope Cowon gets the message.

michael on January 14, 2009 8:29 PM

What?, No 1080p support??!! lol

affainyi on January 14, 2009 9:29 PM

I wouldn’t exactly call the O2 a failure but I would love drastic improvements… is really quite a capable device only hampered by poor software. We all now software is much easier to fix than hardware and so I will stick with my O2 until a suitable competitor in terms of screen size,codec support, battery life and price comes around.

Chris on January 15, 2009 1:11 AM

Wow, what a thorough review. I feel like I have owned this player for a while and I’ve never even touched one. I do appreciate it when it comes to this sort of investment though. For some reason I do feel I have to defend the J cable buds though. It’s just so easy to pop the buds out for a minute or an hour and pop them back in when it’s time to “submerge” back into my media. I’m most familiar with Sony and Sennheiser though, so I’ll have to take your word on the Cowon OEMs. We will just wait and see on the firmware.

andy on January 15, 2009 8:18 AM

I am a first time cowon buyer. I mail ordered the O2 32GB as soon as it was available in Canada. I did lots of pre release research and really felt it was going to be a good investment. I agree with everything in this review – especially the software issues.I am up to date on all of their firmware releases and I would still consider it ‘unacceptable’.I really hope they make some major changes soon – or I will lose all faith in what I understood to be a good brand name and never purchase one of their products again.I guess I that’s the down side with products that are not available in your own town, so you can’t test them out…My eagerness failed me – next time I wait for a review like this.

Martin Sägmüller on January 15, 2009 10:37 AM

Luckily (if you can call that “luckily”), the O2 is the exception to the rule. Most other Cowon players are indeed solid performers. At least “simpler” players like the X5, M3, U3, etc.Although the D2 also had pretty sub-par firmware at release time, but it improved to something much better. It took a year or so, however, until decent firmwares were available – which certainly is an unacceptable time frame. I hope they fix the O2 faster than they were with the D2… but as it looks this is not going to be the case, since v1.19 is the same junk as all other firmwares before.

Notary Sojac on January 15, 2009 4:04 PM

sigh…….Looks like my Palm TX with the SDHC patch and TCPMP will remain as my PMP for the foreseeable future.The O2 was looking to be the first player with native XviD, an SDHC slot, and TV-out – which are my must-haves for a Palm replacement.But it sounds too sucky to even consider……

Anti Apple on January 15, 2009 7:11 PM

GOD WE NEED TO BEAT APPLE!cowon and archos have the potential all they have to do is sit down and think how to just fly by the itouch. not evolving crud into a whole new type of crud

robertw on January 16, 2009 1:54 PM

Unfortunately for the PMPs and the enhanced MP3 player (D2) Cowon has produced, they have never gotten the firmware correct out of the gate. I feel that O2 is a viable player and will only improve over time, but Cowon really needs to get these software issues fixed before release, otherwise they will lose their supporters.With that said, I am hooked on Cowon and will always look to their products first. I love my D2 and still consider it a better purchase than any iPod. Also am seriously looking at getting a Q5W in the near future (blows any other PMP out of the water.)

del on January 18, 2009 2:07 AM

Nice review. Unfortunately, I ordered the O2 the day it was available and have been disappointed ever since.One particularly aggravating popup you missed in the review is for switching between the speaker and the headphone jack. Yep, the player doesn’t even automatically switch to the headphone jack when you plug them in. You have to go click on the speaker and change to it in the popup. Pretty pathetic.

gadget on January 18, 2009 4:50 PM

i have been waiting too long to buy a player..I do not want to buy and ipod…but i might get the ipod touch because i do not have anything and i want to enjoy something.I want something that had good audio and video, bluetooth, wireless, owner can replace the battery, expansion card slot. and i probably forgot some things. I like the fact that ipod has so many after market accessories for it so i can use it as part of a home entertainment center. Unless these aftermarket companies make adapters for the other products so they could work with the ipod accessories..I thought that Creative Labs would have had an ipod killer…somebody should be able to do it…They have been able to see it and use it…Just do it…Thanks for listening and would love to get some suggestions.

Aaron Martin-Colby on January 29, 2009 5:36 PM

I’ve had the O2 since Christmas.I was really excited because of the audio quality and file compatibility, which is a big issue for me and my nine gazillion various media files.I have found the player almost useless. I am so crestfallen. The fact that I can’t change to a portrait layout, tweak any of the colors, and create playlists or sort by ID3 tags is a nightmare. I do not have small hands, and even my girlfriend, who does have small hands, finds navigation problematic.I’ve been using it as a portable hard drive, and will continue to do so for the foreseeable future. I can’t believe I paid money for this.

Epikorean21 on February 11, 2009 9:09 PM

Hello.. I was wondering if the O2 can sync with any other programs other than JetAudio… JetAudio is extremely irritating to use compared to iTunes or the Zune player… I was wondering if Windows Media Player would do the Cowon O2 justice…Thanks.

Cesar Fernandez on February 20, 2009 12:56 AM

Martin:Do you remember which ancient Creative player has pitch correction?I’m looking for a DAP that can do this.Even if it is ancient, I can probably find a used one on ebay or the web.Thanks!Cesar Fernandez

rolie on March 1, 2009 8:58 AM

Wow nice review! It’s good to see something honest without brown nosing adverts. I got excited when I read the AAC support. No playlist support still. Damn Cowon, your reputation is going down the drain fast with me.Gimme a 32gb iaudio8 with AAC support and playlist support that can shuffle properly and keep the long lasting battery of the I7. That thing lasts forever.ipods are for sheep.

Declan O’Neill on July 22, 2009 3:07 AM

Thank you so much for a thorough and professional review. This is one of the best and most comprehensive reviews I have read on any electronic product. It was most useful. Great Job

swede on November 26, 2009 2:06 AM

Its one of the best out there!Batterylife+Sound+Video is easy as hell…just put them in the player they work…no scaling like ipod is needed, saves me a lot of time…just put .srt files in the folder where the movie is…works like a charm!The only negative thing is lika the review says, SD-card slot needs to be integrated.

Michael Maher on September 18, 2010 6:30 PM

FAO: Martin Sägmüller

Hi Martin,

Your reviews are top notch – so refreshing to see this level of critical ‘real world’, user oriented, appraisal.

I have the Shure SE350s, which with the new Comply TX-100 foams, sounds amazing when playing music from my ipod touch (2nd gen with 320 AACs or 320 MP3s).

It made me wonder how things could sound much better. In particular I wondered what the sound would be like, using 24 bit 96KHz FLAC files played from the Cowon O2, perhaps also with the Headstage Arrow 12HE amp in between?

Then I realised that you probably have access to all three, and wondered if you had ever tried, or could try this combo, and let me know your opinion?

I realise the the O2 had issues with clicks and missing beginning of tracks, but its one of the few PMPs that can play the Hi Res tracks, now available from the likes of HD tracks, LINN & 2L. I know that in my home audio setup, Hi Res music makes a tangible jump in AQ over CD, clearly apparent to non-audiophiles like me.

According to most commentators the Touch has inferior audio quality compared to the Cowon and Sony players in particular. However forums suggest a low level of ‘hiss’ on the SE350s with the Touch. In fact there does seem, as you say, to be a burning in period with the SE350s. So that I never noticed any hiss on my recent holiday break,
although the first time I tried the SE350s were with a 3rd gen ipod, and the presence of hiss surprised me, because my previous Shure E3s didn’t have this.

Hope you can find time to check out the above combo and reply. (2L site has free stereo 24bit 96K FLAC downloads if required

Keep up the good work.



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