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• Thread count option in FFmpeg for FASTEST conversion to h264 ?

  5 septembre 2013, par Saptarshi Biswas

  I need to maximize speed while converting videos using FFmpeg to h264

  • Any input format of source videos
  • User's machine can have any number of cores
  • Power and memory consumption are non-issues

  Of course, there are a whole bunch of options that can be tweaked but this question is particularly about choosing the best -thread <count></count> option. I am trying to find an ideal thread count as a function of

  • no. of cores
  • input video format
  • h264-friendly values maybe ?
  • anything else missed above ?

  I am aware the default -thread 0 follows one-thread-per-core approach which is supposed to be optimal. But I am not sure if this is time or space-optimized. Also, on certain testcases, I've seen more threads (say 4 threads on my dual core test machine) finishes quicker than the default.

  Any other direction, say configure options w.r.t. threads, worth pursuing ?

• How to compare/show the difference between 2 videos in ffmpeg ?

  25 janvier 2016, par polarka

  I am a newbie at encoding. I have read and tried x264 in lossless mode (-qp 0), however I’d like to make sure that in my new video, every single pixel contains the same information as the source file (which is in YUV 420 so the loss of color conversion is avoidable, as far as I know). I want to be able to check that, because I don’t believe in that if someone just says its lossless.

  I welcome answers suggesting other codecs for lossless encoding, my only requirements for codecs are having one of the best compression rate and let me to pick different calculation times (such as the range from placebo to veryfast in x264) in order to adjust the compression level and calc time to my needs. But keep in mind that the original question is about how can I calculate the differences frame by frame of two videos and export it to a 3rd file, so I can watch it myself. I think that knowledge (if its possible and doesnt have serious limitations) will be useful for me in the future too.

• equivalent option in ffmpeg for ffplay's -infbuff

  25 septembre 2015, par Paul

  I have a multicast UDP stream that I can watch (with almost no errors) if I use ffplay’s infbuf option.

  But when I try to encode it via ffmpeg, ffmpeg reports a lot of errors and the resultant video has lots of errors.

  I have tried setting the fifo_size to a super large value like 655360 and the buf_size as per https://www.ffmpeg.org/ffmpeg-protocols.html#udp. But none of gets rid of the decode errors in ffmpeg.

  Is it possible to provide settings to ffmpeg that do something similar to what ffplay’s -intbuf does ? I want my video encode to be as error free as video playback via ffplay.