Flash Video
Jul/091
FlashVideo(FLV) is the video format that Macromedia created for their FlashPlayer rich media browser plugin. Due to the fact that FlashPlayer plugin (now owned by Adobe) has a web presence in excess of 97%. It is safe to say that about every computer that connects to the internet can play video in FlashVideo format.
The file format of .FLV files is by design based on the h.263 standard. The newer FlashPlayer(9.0.0.29 or above) supports h.264/mp4 files which may have extension .flv(.f4v).
.FLV (FlashVideo) is a streamable container format which “officially” supports several codecs most notably:
- Sorenson Spark a H.263 based codec which powered the initial success of GoogleVideo, YouTube and all other web video startups of the Flash7 era.
- On2 TrueMotion VP6 is a highly versatile codec delivering superior visual quality and smother motion on lower bitrates. VP6 is available with FlashPlayer 8 or newer. There is a version of the codec called VP6a, which supports transparency data in the video stream. VP6 is more computation intensive than Sorenson Spark and on higher bitrates and has high requirements to the system playing the stream. There is a update to the VP6 codec coming with FlashPlayer 9 that improves performance on higher bitrate streams.
- H.264/MPEG-4 is a modern codec. It is standard. It is versatile. It allows of utilization of hardware acceleration for video decoding. It is intended for HD video. It is licensed.
Sorenson’s Spark codec
Sorenson Spark is the most widely spread codec for web video as it essentially powered the initial boom of video on the internet. It is relatively light in computational complexity and may be a good choice for near HD resolution (up to 540p for example) video, if you want this video to be playable on a laptop powered by a crappy integrated intel video chipset (80+% of the laptops and a the majority of desktop PCs use IGM’s too).
On2′s VP6 codec
VP6 is a excellent codec superior to Sorenson’s h.263 Spark especially on low bitrates. However it is a proprietary codec and is subject to licensing, which restricted it’s actual use of in community video sharing services. VP6 though delivers better visual quality on lower bitrates than any other codec currently in use, even the more recent h.264 based ones.
h.264/MPEG-4 codec
H.264 is the current codec standard. It supports all the bells and whistles you can think of. There are two main problems for the h.264/mpeg-4 codec to beat the above two codecs on the web:
- The use of this codec is subject to royalties which limit it’s use on the web. This codec’s royalty model is perfect for embedded device(cell phones, digital cameras etc.) builders as the cost of implementation is fixed and affordable(comes with the chip implementing the codec), however for a video sharing service the cost can rise the millions. Thus web video services usually would accept your content in that format, but not actually transcode other formats to it.
- Lack of tools – the reason I said above that VP6 actually provides better quality at low bitrates is the fact that VP6 is usually encoded with tools provided by On2. These tools are mature and use “all the features” that the codec supports, while for h.264 you have either basic chip based encoders in a hardware device or basic reference software tools. In most cases the users of h.264/mpeg4 try to compensate this basic use of the codec with higher bitrates, but that defeats the whole purpose when it comes to web video. For example a digital camera I had encoded video at around 5mbps for a visual quality achievable with ten times less of this amount.
Ogg Theora codec ???
Ogg Theora is NOT supported by flash at this time. However I believe it will be supported very soon. Ogg Theora is a free video codec. It is claimed to be comparable in quality with VP6/MPEG-4 generation codecs, however as with h.264/mpeg4 there is a lack of encoding tools that would make that claim true. Theora has huge potential for web video and I firmly believe we will be hearing of it very often from now on.
Tags: flash video format, Video files, Video Hosting, Video Sharing
