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• 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


  


• 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.

  


• Android Studio - Append two videos but showing black screen

  6 septembre 2020, par Darkhmar

  First of all hello,

  


  When I add another mp4 file at the end of an mp4 file, the video looks completely black screen but I can get the video sounds.

  


  If I add a copy of a video to the end of it, I saw that there was no problem, but this is not a scenario I want.

  


  I am getting the "text relocations" error when merging with the FFmpeg library. (This problem is fixed when I change this library version, but I have other problems. Therefore, mp4parser is an alternative I see.)

  


  The piece of code that allows the videos to be merged is as follows. Thank you from now.

  


  private void appendTwoVideos(String firstVideoPath, String secondVideoPath) {&#xA;    try {&#xA;        Movie[] inMovies = new Movie[2];&#xA;&#xA;        inMovies[0] = MovieCreator.build(firstVideoPath);&#xA;        inMovies[1] = MovieCreator.build(secondVideoPath);&#xA;&#xA;        List<track> videoTracks = new LinkedList&lt;>();&#xA;        List<track> audioTracks = new LinkedList&lt;>();&#xA;&#xA;        for (Movie m : inMovies) {&#xA;            for (Track t : m.getTracks()) {&#xA;                if (t.getHandler().equals("soun")) {&#xA;                    audioTracks.add(t);&#xA;                }&#xA;                if (t.getHandler().equals("vide")) {&#xA;                    videoTracks.add(t);&#xA;                }&#xA;            }&#xA;        }&#xA;&#xA;        Movie result = new Movie();&#xA;&#xA;        if (audioTracks.size() > 0) {&#xA;            result.addTrack(new AppendTrack(audioTracks&#xA;                    .toArray(new Track[audioTracks.size()])));&#xA;        }&#xA;        if (videoTracks.size() > 0) {&#xA;            result.addTrack(new AppendTrack(videoTracks&#xA;                    .toArray(new Track[videoTracks.size()])));&#xA;        }&#xA;&#xA;        BasicContainer out = (BasicContainer) new DefaultMp4Builder().build(result);&#xA;&#xA;        @SuppressWarnings("resource")&#xA;        FileChannel fc = new RandomAccessFile(DIRECTORY_PATH &#x2B; "output.mp4", "rw").getChannel();&#xA;        out.writeContainer(fc);&#xA;        fc.close();&#xA;    } catch (FileNotFoundException e) {&#xA;        e.printStackTrace();&#xA;    } catch (IOException e) {&#xA;        e.printStackTrace();&#xA;    }&#xA;}&#xA;</track></track>