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• How can I extract "GROUP-ID", "LANGUAGE" and "INSTREAM-ID" from ts using ffmpeg

  21 novembre 2020, par user1163234

  I am trying to get the captions from a segment from a live feed. I am running the command

  


  ffmpeg -i seg-1077853030-v1-a1.ts

  


  Output

  


  `Input #0, mpegts, from 'seg-109853030-v1-a1.ts' :
Duration : 00:00:06.01, start : 57867.901133, bitrate : 2649 kb/s
Program 1

  


  Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
Stream #0:1[0x101]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 98 kb/s
Stream #0:2[0x102]: Data: timed_id3 (ID3  / 0x20334449)`


  


  My question is what command should I run to print out the caption file with the track metadata including label and language.

  


• What format/protocol does ffmpeg use for "raw" output ?

  9 janvier 2021, par MSalters

  Given a commandline ffmpeg -f lavfi -i "sine=frequency=1000:duration=5" -ar 8000 -c:a FOO pipe:1, ffmpeg might complain it's "unable to find a suitable output format". For some codecs, ffmpeg has a default container format, e.g. -c:a libmp3lame will produce MP3's. For other codecs, you just repeat yourself (sort of) : -c:a pcm_alaw -f alaw

  



  But what if I want to stream the raw codec output, and there's no matching -f ? Can I just take -f alaw and assume that it doesn't do anything ? (G711 alaw is a simple codec which produces a byte stream, so -f alaw presumably just copies that byte stream)

  



  Obviously the other side of the pipe needs to know how the data stream needs to be interpreted, if there's no container info. But assume that I already know the other side of the pipe is expecting an audio stream, sampled at 8 kHz, encoded with -c:a FOO.

  


• Strange "pause" in video after concatenation of two mp4 videos

  23 janvier 2021, par user606521

  I am concatenating two mp4 videos. The problem is that first video (intro.mp4) lasts 5 seconds, second video (output.mp4) lasts 2 seconds and video created by concatenating them lasts 9 seconds (and should last 5+2 = 7 seconds). In final.mp4 video the last frame from first video (intro.mp4) i shown for additional 2 seconds before second video (output.mp4) is played. It looks like a lag when watching video. What I am doing wrong ?

  



  list.txt :

  



  file 'data/intro.mp4'
file 'output.mp4'


  



  command :

  



  ./bin/ffmpeg -f concat -i list.txt -c copy final.mp4


  



  output :

  



  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.100 / 56. 41.100
  libavformat    56. 36.100 / 56. 36.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'list.txt':
  Duration: N/A, start: 0.000000, bitrate: 1296 kb/s
    Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x540, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 47.95 tbc
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 133 kb/s
[mp4 @ 0x7f8a6c006a00] Codec for stream 0 does not use global headers but container format requires global headers
[mp4 @ 0x7f8a6c006a00] Codec for stream 1 does not use global headers but container format requires global headers
Output #0, mp4, to 'final.mp4':
  Metadata:
    encoder         : Lavf56.36.100
    Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 960x540, q=2-31, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 11988 tbc
    Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 133 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
frame=  258 fps=0.0 q=-1.0 Lsize=     997kB time=00:00:09.84 bitrate= 829.5kbits/s    
video:897kB audio:93kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.634306%