Transcode thoughts

• Currently the smallest transcodes we’re producing on Commons are 360p for .webm and 480p for .ogv; the framerate appears unchanged from the original.
• On desktop, 360p generally performs well and 480p may depending on the machine and browser. 360 is about half the pixels.
• On mobile, 360p videos are still generally too slow. Generally I’ve only hit decode framerate targets on iOS with 240p or smaller, especially at 15fps… we don’t produce transcodes that small, so it’s only been successful with smaller files, usually older ones (newer ones are mostly 640×480 or HD sources)
  • 360p and 160p/15fps transcodes are now enabled. Yay!
• High framerates increase the number of pixels that have to be processed significantly; should we consider transcodes with decimated framerates?
  • This works great on the 160p/15fps ones — note that 60fps files transcode to 480 and 360 keeping that 60fps, they should probably be decimated if possible…

At smaller sizes like the 160p/15fps, the vorbis decoding seems to eat a much bigger portion of time… Tremor (integer vorbis lib) actually ran really slow and dominated in this scenario. Back to floating point actually is faster here. :D