Tutorials/Video/Encoding Timebased Media
- 1 Encoding Timebased Media
- 2 True global access to your media
- 3 Other questions
- 4 This is all about video - what about audio?
1 Encoding Timebased Media
Here are some commonly asked questions.
1.1 I'm only encoding into one format: What's this one best format for putting video online?
There was no simple answer to this, but increasingly (Nov 2007) there is one: H.264/AAC. The reason for this is that Flash 9
beta is now supporting H.264/AAC. At the moment it's in beta, but when once it's being used widely, tThe solution is this:
- Encode your video into flash compatible H.264/AAC, e.g. as m4v.
- Make the video available for online viewing via Flash 9 plugin, e.g. using FlowPlayer.
- Link to the video directly as a download. (Downloaded videos will play in VLC, mplayer, iTunes, QuickTime, RealPlayer; it will also play on iPods)
- Syndicate all your videos through a podcast feed. (Videos can thus download into a podcatcher, e.g. iTunes)
You then have both the online viewing audience, as well as the portable players audience, with a single format. One remaining question is whether some sort of low-cost streaming of H.264 into flash players will be possible. At present, you can use a php-based solution, or a light-tpd based solution, to stream (suitable prepared) flvs into flash players. Some info is available on the web, but at present (Nov 2007) there may not be a solution for this. We'll see.
In terms of practical encoding tips: You'd probably want to encode the video into 384x288 or 512x288 (for PAL 4:3 and 16:9, or the equivalents for NTSC, read Interlacing and Pixel Aspect Ratio for background), 300kbps to 500kbps, with 40-60kbps for audio. Preprocess your audio, see Dynamic Range Compression.
About the Flash and H.264, see Flash H.264. Flash 9 is only available since the end of 2007, so if you use flash, you certainly need to do plugin checking, and warn viewers if they don't have flash 9. (Ideally, you'd check for Flash 9. If that fails, check for QT player, then for RealPlayer. If none of those exist, offer the user a download.)
2 True global access to your media
2.1 I've read the low-bandwidth accessibility guidelines, and I am going to encode into two formats.
The web-design guidelines are here: Web Design 4 Low Bandwidth. A key concept in this is the 'video-audio-text' cascade for layered delivery. Hopefully that chapter convinces you to make a low-bandwidth version available.
So suppose you have H.264/AAC available (through a flash player, and as downloads and podcast feed), what's next? The answer is mp3 at 32kbps, as recommended in the web-design guidelines.
mp3 is a widely available format, and at 32kbps relatively good for low-bandwidth delivery.
So if you do two formats, then H264/AAC (in m4v container), and a 32kbps mp3 is the answer.
2.2 I've read the low-bandwidth accessibility guidelines, and I am going to encode into three formats.
In that case, you might also add a format for mobile phone, e.g. 3gp (with mpeg4 part 2 for best compatibility, or H264 for best quality). More information on Multiformat Media Delivery.
3 Other questions
- I've got some automated transcoding workflow going, what formats should I use? See Multiformat Media Delivery.
- It's now 2010 and the format recommended in 2007 no longer works! Well, of course you will have kept your source materials, and you can now encode into a more current format.
- What's pixel aspect ratio and why can't I encode my video to 720x576? See Pixel Aspect Ratio.
- I encode my video to 320x240 and I see strange jagged lines on my video. See Interlacing.