Internet Archive News

updates about archive.org

new mp4 (h.264) derivative technique — simpler and easy!

Greetings video geeks!  😎

We’ve updated the process and way we create our .mp4 files that are shown on video pages on archive.org

It’s a much cleaner/clearer process, namely:

  • We opted to ditch ffpreset files in favor of command-line argument 100% equivalents.  It seems a bit easier for someone reading the task log of their item, trying to see what we did.
  • We no longer need qt-faststart step and dropped it.  we use the cmd-line modern ffmpeg “-movflags faststart”
  • Entire processing is now done 100% with ffmpeg, in the standard “2-pass” mode
  • As before, this derivative plays in modern html5 video tag compatible browsers, plays in flash plugin within browsers, and works on all iOS devices.   it also makes sure the “moov atom” is at the front of the file, so browsers can playback before downloading the entire file, etc.)
Here is an example (you would tailor especially the “scale=640:480″ depending on source aspect ratio and desired output size;  change or drop altogether the “-r 20″ option (the source was 20 fps, so we make the dest 20 fps);  tailor the bitrate args to taste):
  • ffmpeg -y -i stairs.avi -vcodec libx264 -pix_fmt yuv420p -vf yadif,scale=640:480 -profile:v baseline -x264opts cabac=0:bframes=0:ref=1:weightp=0:level=30:bitrate=700:vbv_maxrate=768:vbv_bufsize=1400 -movflags faststart -ac 2 -b:a 128k -ar 44100 -r 20 -threads 2 -map_metadata -1,g:0,g -pass 1 -map 0:0 -map 0:1 -acodec aac -strict experimental stairs.mp4;
  • ffmpeg -y -i stairs.avi -vcodec libx264 -pix_fmt yuv420p -vf yadif,scale=640:480 -profile:v baseline -x264opts cabac=0:bframes=0:ref=1:weightp=0:level=30:bitrate=700:vbv_maxrate=768:vbv_bufsize=1400 -movflags faststart -ac 2 -b:a 128k -ar 44100 -r 20 -threads 2 -map_metadata -1,g:0,g -pass 2 -map 0:0 -map 0:1 -acodec aac -strict experimental -metadata title=’”Stairs where i work” – lame test item, bear with us – http://archive.org/details/stairs’ -metadata year=’2004′ -metadata comment=license:’http://creativecommons.org/licenses/publicdomain/’ stairs.mp4;

Happy hacking and creating!

PS: here is the way we compile ffmpeg (we use ubuntu linux, but works on macosx, too).

Originally posted on The Internet Archive Blog by traceypooh.
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Written by internetarchive

February 9, 2013 at 8:39 pm

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