I've found a good deal of info about this huge subject. I'll list some of my findings here, in hopes that it will help to make decisions on how to provide your future content. All that being said, WMV is still a popular format, and F4M makes it easy to encode your projects for whatever destination is planned.
Video codecs (someone named Jon prepared this info)
• MPEG-2 is commonly used for DVDs and ATSC broadcasts. MPEG-2 doesn’t have particularly efficient compression, so unless you’re creating a playable DVD or broadcasting over the air, you probably won’t create MPEG-2 video files.
• MPEG-4 ASP is a much more interesting format, and it commonly goes by the names XviD or DivX. These codecs provide reasonably good compression, wide compatibility, and a reasonable CPU load for encoding/decoding. DivX is owned by DivX, Inc., while XviD is GNU licensed.
• H.264 is also known as MPEG-4 AVC. H.264 is a more advanced video codec than ASP/XviD (hence the AVC acronym), and provides better compression. How much better? Don’t quote me on this, but IIRC it provides about 35-50% better quality for the same file size. Unfortunately, it has two disadvantages when compared to MPEG-4 ASP. First, H.264 decoders are a little less common than XviD decoders, so compatibility isn’t quite as widespread. Second, encoding and decoding H.264 is more processor intensive than XviD. That said, H.264 is probably the best quality video codec on the market today, or at least is tied for this honor.
• H.263 is, unfortunately, not just an incremental step down from H.264. It is about 8 years older, and provides far worse quality. This is unfortunate, because H.263 is used in at least two prominant places. First, most Flash video is encoded with H.263, including just about everything on YouTube and MySpace. Second, H.263 is often used by cell phones to play or capture video. Despite the low quality, H.263 makes perfect sense if you want to put video on the web and don’t want to use the codec that will be described next – VP6.
• VP6 is a proprietary codec developed by On2 Technologies. VP6 has two major advantages. First, it offers great compression, comparable to H.264. Second, VP6 is used by Flash 8, so it is a great candidate for video that will be played back on the web. The downside is that VP6 can’t be encoded for free; it requires commerical software, like Flash 8, or the On2 Flix Engine. But this may actually not be a downside, as I’ll discuss in a future article on licensing and royalties.
• WMV describes several Microsoft codecs. Confusingly, WMV 7 is also known as WMV1, WMV 8 is also known as WMV2, and WMV 9 is also known as WMV3. (The latter name refers to the codec’s FourCC code, and I think the former name refers a corresponding version of Windows Media Player.) These codecs are not bad, and with Flip4Mac, they are no longer restricted to Windows machines.
• Theora is a truly open-source video codec based on On2’s VP3 codec, as a part of the Ogg project. It provides comparable quality to MPEG-4 ASP (e.g. XviD), and it is BSD-licensed. Did I mention that it is open-source (unlike any of the MPEG, Microsoft, or On2 codecs)? I’ll discuss this in more detail in a future post.
Audio codecs
• MP3 is probably the most famous codec of all time. It is a part of the MPEG-1 standard (MPEG-1 audio layer 3). This codec provides adequate quality at a bitrate of about 128kbps. However, distribution of MP3-encoded content is not free, as will be discussed in a later post.
• For this reason, AAC is a better audio codec than MP3 for most uses. AAC-encoded content is free to distribute, which is one of the reasons why iTunes chose AAC for its content. AAC also provides better compression than MP3 – 96kbps AAC is generally considered equal to 128kbps MP3.
• Vorbis is an Ogg audio codec that is similar in quality to MP3, or perhaps slightly better. Like Theora, it is truly free (unlike AAC or MP3).
• FLAC and Apple Lossless are two lossless codecs that provide about 50% size savings compared to uncompressed audio. FLAC is part of the Ogg project, and I’m not sure who developed Apple Lossless.
• AC-3 is the Dolby Digital audio codec that can store 5.1 channel audio.
Formats
• MOV is the Quicktime container format. It is a reasonably good format, with pretty widespread compatibility (every computer with iTunes installed also has Quicktime) and decent codec support. One major advantage of Quicktime is that MOV files can be played back in many browsers (though not all).
• MP4 (MPEG-4 part 14) is based on Quicktime and is very similar, but it supports some codecs and encoding options not supported by MOV (like advanced H.264 profiles). Most media players can play MP4, though not in a web browser.
• AVI is an old format (1992!) that is somewhat outdated today. It has pretty good codec support, though it isn’t able to handle some modern codecs very efficiently, including XviD and H.264. Ask yourself why you want to use AVI instead of a more modern format.
• ASF is a proprietary Microsoft format. If you’re primarily using a Microsoft codec and Microsoft players, ASF may be a good option.
• OGG is a free, open-source format released under the BSD-license that typically is used with Vorbis, Theora, FLAC, and other Ogg codecs. However, the Ogg container format can wrap other formats (like MP3 and various MPEG-4 codecs).
• FLV is the Flash Video format, and offers by far the best web browser compatibility – likely in the 99% range for folks with up-to-date computers. Of course, there are several versions of Flash Player, and so if you’re on the bleeding edge, the number may be lower. Unfortunately, FLV only supports two codecs: H.263 (bad) and On2 VP6 (great but commercial).
