Once upon time, video codecs and formats were really only the concern of AV nerds, anime freaks and hardcore not-so-legal movie downloaders. Now, even the most part-time of geeks has to deal with them, whether they're trying to stream a flick across their house with an Apple TV, dump some video onto their phone or just trying to grab last night's episode of Dexter because they, uh, forgot to renew their Showtime subscription. It's messy and annoying, but we're here to clean it up. Take a deep breath.

You might recall our discussion about video bitrates earlier, or how much data is packed into a file. As a general rule, more bits per second translates into more betterer quality audio and video. The variable in that—the other part of the equation—is how the content is compressed and de-compressed. Better compression techniques—the zen of knowing what bits of data to pull out to make big data chunks smaller—make for better quality video while taking up less space on your hard drive. Basically, the part you need to know is that codecs are the software that make that magic happen.

Standard Standards
• H.261 is not a term you have to worry about, but it's the technology that most video standards and codecs were originally based on. Originating in 1990, it's the first major digital video compression standard, and like other "H" standards, it was developed by the International Telecommunication Union. This one was primarily for teleconferencing over ISDN lines, and as such, it looks like ass.

• MPEG-1 Part 2 is another oldie, developed by the Movie Picture Experts Group and approved in 1991. (BTW, the whole "part" thing is because video is just one "part" of each MPEG standard.) Based quite a bit on H.261, MPEG-1 was designed to take VHS quality video and squeeze it down to a bit rate of about 1.5Mbps, optimized for CD transfers. No surprise, it's the standard used for all VCDs (which can play in most DVD players), but not a standard you would see hanging around today.

• With MPEG-2 Part 2, approved in 1994, we're finally talking decent vid. Also known as H.262, since it was developed jointly by the ITU-T and ISO, MPEG-2 is an extension of MPEG-1 that delivers better resolution and higher bit rates (3-15Mbps for standard def and 15-30Mbps for HD, though the spec allows for up to 100Mbps). It's the video codec used by DVD and digital television, though now it's slowly being replaced by the more efficient MPEG-4, except on DVDs, where it'll ride out that disc format's lifetime.

• H.263 is designed for sending video over crappy connections. So it's used to encode most Flash video and to send video over mobile networks.

• MPEG-4 is where we really stand right now. It has a much broader scope than past MPEG standards, aiming to tackle both the low end (crappy cellphones on a crappy network) and the high end (Blu-ray). It's still developing, so it's not-so-coincidentally where this whole story gets messier. There are two relevant parts of the MPEG-4 standard for our myopic video purposes: There's Part 2. And there's Part 10—which is also known as H.264 or Advanced Video Coding (AVC). To be clear though, even though they're both part of the MPEG-4 standard, they're totally different formats. Nevertheless, both are more efficient at compression than past MPEG codecs, delivering better quality using less space.

• Okay, so if you've ever frequented a Torrent site, you've actually watched tons of videos that use MPEG-4 Part 2, though it's not like they would've had a flashing sign telling you so. MPEG-4 Part 2 actually has different "profiles"—the two that matter being Simple Profile, for low bitrate, low-res stuff, and Advanced Simple Profile. The latter profile is what's used by movies you would download in formats like DivX or XviD or 3ivx—which are all codecs that are essentially just differing implementations of the MPEG-4 Part 2 standard.

• MPEG-4 Part 10, the other part, was actually co-devopled by MPEG and the ITU-T, so it's also known—in fact, more commonly known—as H.264. It's more efficient than MPEG-2 and MPEG-4 Part 2, delivering the same quality video in as little as half the space, making it suitable for the low and high-end. Because of this, it's quickly becoming the standardest standard. It's part of the HD DVD and Blu-ray spec, replacing MPEG-2 in digital TV (like with satellite services and AT&T's U-Verse IPTV) and supported by pretty much every portable video player on the planet from the iPod to the PSP. Apple has a decent, if Kool-Aid flavored, FAQ about H.264.

• VC-1 is essentially a Microsoft developed alternative video codec to H.264 released as a standard by the Society of Motion Picture and Television Engineers, though it descends from the same H.26X/MPEG family. (It essentially started life as WMV9, but then Microsoft shopped it to the SMPTE to make it an industry standard, and now it is.) It too, is part of the mandatory Blu-ray and HD DVD spec, and is the official video codec of the Xbox 360. It's pitch is the same as H.264's—trying to deliver better quality using less space, like HD video in 6-8Mbps.

Free-Floating Codecs
Okay, so all that stuff up there are industry-wide standard video codecs. On top of all of those, various entities love putting out their own spin on those standards. As we mentioned before, DivX (proprietary) and XviD (open source), for instance, use MPEG-4 Part 2 (more specifically, MPEG-4 ASP) compression, meaning stuff that'll natively play back MPEG-4 ASP will also play back DivX. Like the Xbox 360, for instance. There are a ton of MPEG-4 ASP-based codecs, actually, like FFmpeg, 3ivx and others, but DivX and XviD are the most common. Same deal with H.264: Some well known codecs that use it are Apple's Quicktime H.264, x264 and Nero Digital. You've also got Windows Media Video (WMV) codecs, which are Microsoft's proprietary twists on industry standards.

Containers aka Wrappers
Alright, well you've probably noticed that none of your video files have the extension .h264 or .vc1 or the like. That's because videos are packaged in containers or wrappers that stuff things like the audio, navigational info, etc. along with the video in a single pretty file. Naturally, there are about as many of them as there are codecs. To be clear, you would take a video encoded with, say, H.264, and wrap it up as a .mp4 or .avi file.

The majors ones are:
• AVI (Audio Video Interleave) is Windows' standard multimedia container
• MPEG-4 Part 14 (known to you as .mp4) is the standardized container for MPEG-4
• FLV (Flash Video) is the format used to deliver MPEG video through Flash Player
• MOV is Apple's QuickTime container format
• OGG, OGM and OGV are open-standard containers
• MKV (Mastroska) is another open-specification container that you've seen if you've ever downloaded anime
• VOB means DVD Video Object. Guess what? It's DVD's standard container, and what you get when you rip a DVD.
• ASF is a Microsoft format designed for WMV and WMA—files can end in .wmv or .asf

So, in order to play a video file, your setup has to be able to handle both the actual video codec and the container. It's why you can try to play an AVI file and Windows Media Player laughs at you, even though it totally played one a minute ago— the container was no problem, but it didn't have the right codec. Or conversely, even though an iPod could play back an H.264 encoded video, if it was wrapped up in MKV, it won't be able to read it.

Okay, my brain hurts. Hopefully this will make yours hurt less when it comes to dealing with pesky videos. If you'd like to do even more homework, Wikipedia, as always, has a more in-depth discussion. And Doom9 is always an amazing resource for all things digital video.

Something you still wanna know? Send any questions about codecs, kitties or pad thai (but not RealMedia) to tips@gizmodo.com, with "Giz Explains" in the subject line.

[Image: ME@Flickr]

It'll play every file you throw at it: on the audio front, we've got (take a deep breath) MP3, WMA, AAC, AC3, FLAC, OGG, Monkey Audio, and a bunch of others I've barely heard of. For video, which is the real draw of the O2, we've got AVI, WMV, MP4, MKV, H.264, DivX and XviD, and again, way more. It'll play videos up to 1,280x720 resolution at 30 FPS. What does that dictionary of acronyms mean? No more converting videos. Ever.

The GUI looks a little dated, awfully similar to my aging D2, but very functional all the same. The O2 has Cowon's vaunted stellar sound quality, but battery life isn't all that hot: 8 hours of video, which is great, but only 18 hours of audio, which is below average these days. Still, this looks to be right at the top of the heap of portable video players, if only because it'll actually play your videos without making you transcode first. The Cowon O2 goes on sale tomorrow (the 25th) in black or white, direct from the manufacturer. [CNET]

As far as upgrade details go, the PS3 is DivX-certified, meaning not only is playback guaranteed to function properly, but game developers can also use the compression format for in-game cutscenes In comparison, the Xbox 360 merely supports playback of DivX-encoded videos [DivX]

Update: Not just free for Macs! Windows version here. Thanks hebrewbacon.

Product Page [DivX via Macenstein]

Among the more interesting answers (as if knowing what setting to choose when re-encoding content for your Xbox 360 wasn't interesting enough) is the "No" to "Do you support DivX", the "No" to whether they support MPEG-2, and the fact that you can now play back some 1080 content at 30fps. Hit the jump for a look.

1. What exactly does the Xbox 360 support for H.264?

Xbox 360 supports the following for H.264:

· File Extensions: .mp4, .m4v, mp4v, .mov

· Containers: MPEG-4, QuickTime

· Video Profiles: Baseline, main, and high (up to Level 4.1) profiles.

· Video Bitrate: 10 Mbps with resolutions of 1920 x 1080 at 30fps. See question number 6 for more information.

· Audio Profiles: 2 channel AAC low complexity (LC)

· Audio Max Bitrate: No restrictions. See question number 6 for more information.

2. What exactly does the Xbox 360 support for MPEG-4 Part 2?

Xbox 360 supports the following for MPEG-4:

· File Extensions: .mp4, .m4v, .mp4v, .mov

· Containers: MPEG-4, QuickTime

· Video Profiles: Simple (including Simple profile content mislabeled as Advanced Simple)

· Video Bitrate: 5 Mbps with resolutions of 1280 x 720 at 30fps. See question number 6 for more information.

· Audio Profiles: 2 channel AAC low complexity (LC)

· Audio Max Bitrate: No restrictions. See question number 6 for more information.

3. What exactly does the Xbox 360 support for WMV (VC-1)?

Xbox 360 supports the following for WMV:

· File Extensions: .wmv

· Container: asf

· Video Profiles: WMV7 (WMV1), WMV8 (WMV2), WMV9 (WMV3), VC-1 (WVC1 or WMVA) in simple, main, and advanced up to Level 3

· Video Bitrate: 15 Mbps with resolutions of 1920 x 1080 at 30fps. See question number 6 for more information.

· Audio Profiles: WMA7/8, WMA 9 Pro (stereo and 5.1), WMA lossless

· Audio Max Bitrate: No restrictions. See question number 6 for more information.

4. How do I create H.264 and MPEG-4 Part 2 content? What encoders does Xbox 360 support?

You can create this content on one of many 3rd-party applications. Xbox 360 supports many popular encoders.

5. What are the different ways to play video content on Xbox 360?

You can play video from a USB 2.0 FAT32 removable drive, optical media, and by streaming from the Zune software or Windows Media Player 11.

6. What is the "real" max bit rate, resolution, and frames per second that you support for all the different formats?

Xbox 360 does not specifically block video from playing based on a maximum bit rate, resolution, or frames per second. The maximums listed above for each codec are what we have tested for various video playback sources. Higher rated content will not be blocked, but playback may be less then optimal. Use higher bitrates at your own risk.

7. What is the maximum video file size that is supported?

The maximum file size for an MPEG-4 Part 2 and H.264 file that can be played is 4 GB. However, Windows Media Player 11 and the Zune software do support streaming WMV files greater than 4GB.

8. Do you support 5.1 channel AAC?

No. Only 2-channel AAC is supported. If you want to play a 5.1-channel video on your console, you will need to encode it to WMV with WMAPro 5.1 audio.

9. Do you support DivX?

No.

10. Do you support MPEG-2?

No. Xbox 360 Media Center Extender does support MPEG-2, but you can't play this content in the Xbox 360 video player .

11. Does Xbox 360 Media Center Extender support MPEG-4 Part 2 and H.264?

Not at this time. You must play these videos in the Xbox Dashboard.

12. Does Xbox 360 display embedded artwork for MPEG-4 Part 2 and H.264 files?

Yes. You can embed your artwork that is less than 400KB in the video files and they will be shown in the Xbox 360 video area when streaming from the Zune software.

13. How do display modes work?

There are 5 display modes: auto, letterbox, fullscreen, stretch, and native. You can access these modes while watching a video by pressing Display on your remote or A on your controller.

a. The auto setting attempts to automatically determine what the best viewing experience is for your video. If it is a very low quality video, it will enlarge it enough to be viewable on your screen while limiting the size for optimal viewing. If the video is of higher quality, it will it will enlarge it to fit the TV. For both scenarios, it will retain the aspect ratio of the original video (for example, 4x3 or 16x9).

b. Letterbox mode will display your image full screen while retaining the aspect ratio of the original video. Use this if you want to override the auto function and fit the content to your TV.

c. Fullscreen mode will display your image full screen with the assumption the video is 16x9 formatted for 4x3 screens. This can be helpful for older content that may be 4x3 with black bars encoded into the video. This mode will allow you to zoom through the black bars and see it as wide screen.

d. Stretch mode will display your image full screen and stretch 4x3 content horizontally to fill a 16x9 TV. This can be helpful for those who always want to fill their TV regardless of the aspect ratio of the content. This causes 4x3 content to appear stretched.

e. Native mode allows you to see the content at its original resolution. Use this to view content that is extremely low resolution or very low bitrates.

14. How are display mode settings saved?

Every time you watch a new video, the display mode defaults to auto. If you decide to change the setting, each time you watch the same video the console will remember what you chose last time.

15. What is the information bar?

The information bar on the on-screen display (OSD) now shows you exactly where you are in the video and where the chapters are in the file. In addition, for downloaded content, it will also show how much of the video has been downloaded.

16. How are the chapters determined?

Each video is divided into 10 chapters, allowing you to quickly move around the video content. Use skip to move to the next or previous chapter. Each chapter appears as a tick on the information bar.

17. Can I fast forward, rewind, and skip while watching content while it's being downloaded from Xbox Live Marketplace?

You can move around in video you have already watched. For example, if you watch 15 minutes of a TV show, you can to go back 10 minutes and then skip forward to the 15 minute mark again (where you left off). After the video is fully downloaded, you can move through the entire video.

18. After the May 2007 update, my 3rd party software doesn't stream videos correctly. Why?

Video navigation was changed in the May 2007 update. 3rd party software that does not support folders through network sharing will not work correctly. You'll have to contact the software developer for support.

19. How can I set up Windows Media Player 11 or Zune to share my media to my console?

For info about setting up sharing, see http://www.xbox.com/en-US/support/systemuse/xbox360/digitalmedia/pc.htm.

20. Should I continue to use Windows Media Connect (WMC) to stream video to my Xbox 360?

Windows Media Connect can be used but is no longer supported. You can manage and stream content to Xbox 360 with Windows Media Player 11 or the Zune software.

21. What are the different video codecs that Zune and Windows Media Player support out of the box for streaming?

The Zune software supports unprotected WMV, MPEG-4 Part 2 and H.264. Windows Media Player 11 supports protected and unprotected WMV.

22. How can I get Windows Media Player 11 to stream MPEG-4 Part 2 and H.264 to my console?

By default, Windows Media Player 11 does not support MPEG-4 Part 2 and H.264. You can either convert your MPEG-4 Part 2 and H.264 content to WMV or you can install a 3rd party MP4 DirectShow decoder pack to import MPEG-4 part 2 and H.264 files into your library. Once they are in your library they can be streamed to your console just like WMVs.

23. I can't see my video files from the Zune software on my console. What's wrong?

Make sure that the folders containing the videos you want to share with your console are included in the Zune software's list of monitored folders.

24. I received a message that says a media update is required to play the content. When I download the update I get the message "The download could not be completed. Please try again later. Any points you used for this transaction have already been deducted from your balance and will not be deducted again" with error code 8070005. Explain.

You'll get this error if you previously downloaded the media update on another Xbox 360 console with the same profile. You are only allowed to download the update on one console per profile. You can work around this by creating a temporary Silver membership to download the update. Once it's downloaded, you will be able to use the update with any profile.

– Jason Chen

Spring '07 Video Playback FAQ [MSDN]

We've tried a few converters online for the Zune, but after converting to M4V, the Zune converts that video again for some reason.

Format conversion's pretty easy, and although the program hung when we tried it ourselves, we don't imagine that there would be any huge problems with it. We'll give it another shot and report back. – Jason Chen

Product Page [m2solutions]

Check out PC Magazine's enthusiastic take on the service, even though columnist David Janowski was looking at an early beta. It looks like SightSpeed has found a hole in the Skype armor, bringing high-quality video to Web conferencing at long last. Might be worth a look. – Charlie White

SightSpeed Site [via TechCrunch]