[FFmpeg-user] FLV to MP4 conversion

Ben Halhead ben.halhead at quvex.com
Thu Mar 8 11:23:38 CET 2012


We are using HDFVR - http://hdfvr.com/ - to record flv files from the 
user's webcam. The .flv files appear fine and playback at a good 
quality, however we are then trying to convert the to .mp4 files with 
ffmpeg and this is where we are hitting problems.

At first we used a custom build installed by a Rackspace technician with 
ffmpeg experience, I believe thsi was version 0.5.2. This worked 
intermittently but on some larger files we would get the error "error 
[libx264 @ xxxxxxxx]error, non monotone timestamps xxxxx >= xxxxx" and 
the encoding would fail. The ffmpeg command used for this conversion was 
"ffmpeg -i PATH_TO_CURRENT_FILE.flv -acodec libfaac -ab 96k -ac 2 
-vcodec libx264 -vpre hq -vpre ipod320 -threads 0 -crf 22 

Unsure of whether this was a problem with the input file or the ffmpeg 
installation we then fired up a cloud server and installed ffmpeg 
ourselves via this link - 
http://ffmpeg.org/trac/ffmpeg/wiki/CentosCompilationGuide. Now we can 
encode the file fully to .mp4 however the audio plays back fine whilst 
the video stutters as if buffering on a dial up connection.

Can anyone give any advice either on the first issue with the 'non 
monotone timestamps' or on the second issue and maintaining a good sync 
with the video and audio?

Any advice/instruction is greatly appreciated.

Many thanks
Ben Halhead

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