[FFmpeg-user] Faster codec with alpha

[Joshua Grauman]

Hello all,

I am using the following command successfully to generate a screencast. 
The video comes from my program 'gen-vid' which outputs the raw frames 
with alpha channel. The resulting .avi has alpha channel as well which is 
my goal. It all works great except that my computer can't handle doing it 
real-time. So I am wondering if there is a different vcodec I could use to 
achieve the same result that was less demaning on the cpu? I am willing to 
sacrifice some compression for more speed, but would prefer not to have to 
store all the raw frames without any compression. Storing the alpha 
channel is also a must. It is preferable if the compression is lossless. 
Does anyone have any other suggestions for compression other than png that 
may be faster? Thanks!

./gen-vid | ffmpeg -f rawvideo -pixel_format bgra -video_size 1920x1080 -framerate 30 -i - -vcodec png over.avi

Josh