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• Avconv / FFmpeg - VOB to mp4

  26 septembre 2017, par 0ne_Up

  I am using avconv/ffmpeg to convert VOB files copied from a DVD to mp4. The command I’m using is

  avconv -i "concat:1.VOB|2.VOB|3.VOB|4.VOB|5.VOB" -c:v libx264 -crf 28 -c:a libvo_aacenc -b:a 128k output.mp4

  This is working, but I’ve seen many different commands using different kinds of arguments, and I’m wondering if this is the "right" way to do it, and if someone has suggestions about which arguments I should (not) use and why (not). The file should be compatible with mobile devices and smart TV’s. I’ve also seen "libmp3lame" being used as audio codec, is it better to use AAC or MP3 ?

  The file size is 732.6MB for a video lasting 00:58:37, is this reasonable ?
  Maybe I can use something to reduce the filesize further without too much quality loss ?

  I’m also confused about the difference between Avconv and FFmpeg. I thought that FFmpeg is deprecated and Avconv is "newer and better", I have two installations of Linux Mint, when I run "avconv —help" on a 17.1 installations I see

  avconv version 9.20-6:9.20-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers

  And when I run the same command on a 18.1 installation I see

  ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers

  Is avconv newer than ffmpeg or is it just a different name for the same thing ?

• Linux : Create a file for writing with controlled flushing to disk in large chunks [closed]

  12 août 2023, par Pete

  On Linux I have a process (ffmpeg) that writes very slowly (even slower than 1kb / s sometimes) to disk. Ffmpeg can buffer this to 256kb chunks that get written infrequently but ffmpeg hangs occasionally and if I try to detect these hangs by checking that the file is being updated I need to wait a long time between updates, up to 10 or 15 mins, otherwise I can sometimes mistakenly kill the ffmpeg process when it appears to have stopped writing when it fact its still filling its internal buffer.

  


  Theres no way to detect this it seems unless I use strace (that I can find anyway). So I am wondering about turning off buffering in ffmpeg and writing unbuffered to disk from ffmpeg.

  


  This will result in the disk constantly making tiny writes and wasting power (and probably, if I use a SSD, mess with wear levelling too).

  


  So I would like to make ffmpeg write to a 'virtual file' (in memory - either kernel memory or a process) which I can specify the flushing characteristics of. The idea being to perhaps specify flush every 2 minutes, then I can keep an eye on the file size and make sure its still being written.

  


  I don't think I've missed any other ways to do this job - even if I could watch the socket stream incoming to ffpmeg the process itself could still stop writing and lose data. Doing the buffering outside of ffmpeg seems like the best way.

  


  Is there a built in way to do this in Linux or does it mean a custom process ? I guess I know how to do this with a small C program and pipe the data in but I wonder if theres a neater way.

  


• lavu/tx : improve 3-point fixed precision

  14 février 2020, par Lynne

  lavu/tx : improve 3-point fixed precision
  There's just no reason not to when its so easy (albeit messy) and its also
  
  reducing the precision of all non-power-of-two transforms that use it.
  

  • [DH] libavutil/tx_priv.h
  • [DH] libavutil/tx_template.c