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• fftools/ffmpeg : drop the -async option

  30 août 2022, par Anton Khirnov

  fftools/ffmpeg : drop the -async option
  It has been deprecated in favor of the aresample filter for almost 10
  
  years.
  Another thing this option can do is drop audio timestamps and have them
  
  generated by the encoding code or the muxer, but
  
   for encoding, this can already be done with the setpts filter
  
   for muxing this should almost never be done as timestamp generation by
  
    the muxer is deprecated, but people who really want to do this can use
  
    the setts bitstream filter
  

  • [DH] doc/ffmpeg.texi
  • [DH] fftools/ffmpeg.c
  • [DH] fftools/ffmpeg.h
  • [DH] fftools/ffmpeg_filter.c
  • [DH] fftools/ffmpeg_mux.c
  • [DH] fftools/ffmpeg_opt.c

• Trying to concat videos from different sources with ffmpeg and get different broken results every time (partly no audio and/or fast forward video)

  30 octobre 2022, par Oliver

  I am using ffmpeg for years to create (merge and render) big video files from the (vaction) clips my sony camcorder produces. My basic workflow is to copy the mp4 files from the camcorder over to my pc, put the names in a file (file 'filename') and use the following command to create one big file that is playable by my apple tv :

  


  ffmpeg -f concat -safe 0 -i filelist.txt -c:v libx265 -preset slow -x265-params strong-intra-smoothing=0:merange=58 -crf 24 -c:a aac -b:a 320k -tag:v hvc1 output.mp4


  


  i cannot explain most of the arguments in total detail but i know that it works.
My problem occurred as i wanted to prepend some video clips recorded with an iphone to one of those files. So the first part seemed easy, the sony camcorder files have a resolution of 3840x2160 and the iphone video clips have a resolution of 1280x720 so at first i upscaled the iphone files using this command (i would have rather done in just one step but i do not know how to do that) :

  


  ffmpeg -i IMG_1182.MP4 -vf scale=3840:2160 IMG_1182_3840x2160.MP4


  


  then i just tried to add those upscaled video files to the filelist from the first command and ran the command for all clips again. Sadly that did not worked, as the resulting file contained all clips but only the iphone part had audio ! For the rest of the video the audio was missing. At this point i also did not noticed that the second part was played much faster (like played in fast forward mode). So guessed that i have to render the iphone and sony camcorder clips separately using the first command. That worked and i got two video files with perfect audio and video. My next step was to concatenate the resulting files using the following simple command :

  


  ffmpeg -f concat -safe 0 -i concatlist.txt -c copy output.mp4


  


  where concatlist contained both files.
Sadly that also did not worked. I do got a file containing both parts, this time with audio, but the video of the second part still was fast forward !

  


  I do not know what to do at this point, and i also do not understand enough to experiment with the options any more. Can someone explain to my what could be the problems here and how to solve them ?

  


• How does MPG determine its default audio track ?

  1er octobre 2022, par codedread

  I have some mpg files that I transcoded from DVDs I bought a long time ago (maybe 20 years ago). ffprobe :

  


  Input #0, mpeg, from 'da-orig.mpg':
  Duration: 00:06:59.44, start: 0.044100, bitrate: 6354 kb/s
  Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, progressive), 720x480 [SAR 8:9 DAR 4:3], Closed Captions, 31 fps, 59.94 tbr, 90k tbn
    Side data:
      cpb: bitrate max/min/avg: 7500000/0/0 buffer size: 1835008 vbv_delay: N/A
  Stream #0:1[0x85]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
  Stream #0:2[0x83]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
  Stream #0:3[0x81]: Audio: ac3, 48000 Hz, mono, fltp, 192 kb/s
  Stream #0:4[0x80]: Audio: ac3, 48000 Hz, mono, fltp, 192 kb/s


  


  This shows there are 4 audio streams. When I play this file in VLC / QuickTime it seems that Audio Track 4 is the default. I'd like to understand how this is chosen. Is it something within the mpg container format or are players choosing the stream that has the lowest id (0x80) ?

  


  More background, when I try to turn this into a mp4 file with the following command :

  


  ffmpeg -i da-orig.mpg -c copy -map 0 da-copy.mp4

  


  I get roughly the same size file, but the default audio track is stream #0:1[0x85].

  


  What I want is an equivalent mp4 file (so the same audio track chosen).