sameersbn
21st February 2011, 21:56
Hello,
I have installed the latest git version of ffmpeg and x264 (and other supporting libraries). I am trying to encode a file so that i can stream it over http. I wanted to get the video bitrate at 800kbps. For this is performed a two pass encode using ffmpeg:
ffmpeg -i sample.m4v -vcodec libx264 -vpre medium_slowfirstpass -b 800k -an -pass 1 -threads 0 -f matroska /dev/null
ffmpeg -i sample.m4v -vcodec libx264 -vpre medium -b 800k -an -pass 2 -threads 0 -f matroska sample.mkv
What i have noticed is that the bitrate of the encoded video is not 800kbps, but rather varies over the entire file. Meaning certain part of the file maybe a lower bitrates while other parts may be well over 1300kbps.
It seems that variable bitrate is being used and the bitrate is adjusted over the entire duration of the file. I would like the file to be converted strictly at 800kb per second and never go higher .
This is important for me since i want to stream the file over http. I have been trying in ffmpeg to get this working, but so far no luck.
Please help!
Thanks and Regards
~Sameer
I have installed the latest git version of ffmpeg and x264 (and other supporting libraries). I am trying to encode a file so that i can stream it over http. I wanted to get the video bitrate at 800kbps. For this is performed a two pass encode using ffmpeg:
ffmpeg -i sample.m4v -vcodec libx264 -vpre medium_slowfirstpass -b 800k -an -pass 1 -threads 0 -f matroska /dev/null
ffmpeg -i sample.m4v -vcodec libx264 -vpre medium -b 800k -an -pass 2 -threads 0 -f matroska sample.mkv
What i have noticed is that the bitrate of the encoded video is not 800kbps, but rather varies over the entire file. Meaning certain part of the file maybe a lower bitrates while other parts may be well over 1300kbps.
It seems that variable bitrate is being used and the bitrate is adjusted over the entire duration of the file. I would like the file to be converted strictly at 800kb per second and never go higher .
This is important for me since i want to stream the file over http. I have been trying in ffmpeg to get this working, but so far no luck.
Please help!
Thanks and Regards
~Sameer