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• ffmpeg : Infinite length output when overlaying subtitles onto black image

  18 juillet 2020, par rosuav

  I'm trying to do some analysis of image-based subtitles by outputting them as a sequence of PNGs to a pipe. My command line looks like this :

  


  ffmpeg -y -i $INPUTFILE -f lavfi -i color=c=black:s=1920x1080 -filter_complex "[1:v][0:s:5]overlay[v]" -shortest -map "[v]" -c:v png -f image2pipe - | pike subspng.pike


  


  In theory, -shortest should mean that the stream stops at the shortest input, which would be roughly seven minutes of input file. Instead, my script receives an infinite sequence of black frames after the last frame of subtitles, until I send FFMPEG a SIGINT. Placing -shortest before -filter_complex has the same effect.

  


  Is there a different way to force the filtering to stop at the end of the input file ?

  


  EDIT : Using the shortest=1 flag on the overlay filter also doesn't help, even in combination with -shortest.

  


• How to concat videos with FFMPEG without a black frame in the middle

  21 juillet 2020, par david k

  I need to join two videos together programmatically, and FFMPEG seems to be working perfectly except it leaves a single black frame between the two joined videos.

  


  Based on this post, I'm guessing it's because the video and audio streams aren't exactly the same length (not sure why). Since I'm seeing a black flash, I'm guessing that the audio is slightly longer than the video, but I can't figure out how to remedy that. I'm fine losing a tiny piece of the audio at the end of the file.

  


  Can anyone help me "trim" the end of my audio stream so that it matches my video stream ? I need to be able to do this for many files, so I can't just hard-code a value into my command.

  


  I've attempted both of the methods that FFMPEG provides to concat, and both of them have this issue. I'd be fine with either approach, if I can get rid of the black frame.

  


  Transcode :

  


  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex \
  "[0:v][0:a][1:v][1:a] concat=n=2:v=1:a=1 [outv] [outa]" \
  -map "[outv]" -map "[outa]" output.mp4


  


  Re-wrap :

  


  ffmpeg -f concat -i files.txt -c copy output.mp4


  


  Here is the output of ffmpeg -i video1.mp4 -i video2.mp4 :

  


  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.16)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_1 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags='-I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.0.1.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.0.1.jdk/Contents/Home/include/darwin -fno-stack-check' --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2020-07-20T20:43:05.000000Z
  Duration: 00:00:09.88, start: 0.000000, bitrate: 1330 kb/s
    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 53 kb/s (default)
    Metadata:
      creation_time   : 2020-07-20T20:43:05.000000Z
      handler_name    : AAC audio
    Stream #0:1(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 1280x720, 1274 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 2020-07-20T20:43:05.000000Z
      handler_name    : H.264/AVC video
      encoder         : AVC Coding
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'video2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2020-07-20T20:43:06.000000Z
  Duration: 00:00:11.68, start: 0.000000, bitrate: 1346 kb/s
    Stream #1:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 53 kb/s (default)
    Metadata:
      creation_time   : 2020-07-20T20:43:06.000000Z
      handler_name    : AAC audio
    Stream #1:1(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 1280x720, 1289 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 2020-07-20T20:43:06.000000Z
      handler_name    : H.264/AVC video
      encoder         : AVC Coding
At least one output file must be specified


  


• add black&silence to beginning of a video

  21 août 2020, par Richard

  Hi I am struggling to add black&silence to the begining of a video with ffmpeg. I did search a lot but they look too complex for me.
Below command is what I find to add black&silence to the end of of video, now how can I tune it to the beginning of a video ?

  


  ffmpeg -i input.mp4 -f lavfi -i color=s=1920x1080:d=10 -filter_complex [0:v][1]concat -af [0]apad -shortest output.mp4


  


  Looks I need to use adelay instead of apad, below is the command that makes sense to me, but the audio is not delayed.

  


  ffmpeg -i input.mp4 -f lavfi -i color=s=1920x1080:d=10 -filter_complex [1][0:v]concat -af [0]adelay=10  output.mp4


  


  Here is the input info and ffmpeg version :

  


  ffmpeg -i input.mp4 
ffmpeg version 4.2.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls     --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb     --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab     --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.29.100
  Duration: 00:01:00.00, start: 0.000998, bitrate: 2526 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 2394 kb/s, 24 fps, 24 tbr, 16k tbn, 48 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 124 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
At least one output file must be specified


  


  Thanks !