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• use ffmpeg to cut video,the video will have extra duration

  17 juin 2021, par Venus

  ffmpeg -ss 2 -i input.mp4 -c copy -t 5 out.mp4


  


  after I executed the ffmpeg command.
  
the out.mp4 total have 7 seconds,it starts from the second frame of input.mp4 to the seventh frame of input.mp4.
  
It only has 5 effective seconds of the input.mp4, the last 2 seconds of input.mp4 is empty.

  


• ffmpeg -concat slowing down AAC audio files

  28 août 2014, par Marc

  I am concatenating six m4a files with this command

  ffmpeg -f concat -i audiofiles.txt -c copy all_audio_edited.m4a

  each file has a duration of 6 hours (24 in total) but the concatenation doesn’t work quite well : the first part of the file (the first m4a) is perfect, but all the others are slowed down, so the final duration is >26 hours

  What’s wrong ?

  Thanks

  Marcs-MacBook-Pro:Sof marc$ ffmpeg -report -f concat -i audiofiles.txt -c copy all_audio_edited.m4a
  
  ffmpeg started on 2014-08-28 at 23:35:06
  
  Report written to "ffmpeg-20140828-233506.log"
  
  ffmpeg version 2.3 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Aug 26 2014 17:59:15 with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-libfreetype --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-aacenc --enable-libass --enable-ffplay --enable-libspeex --enable-libschroedinger --enable-libfdk-aac --enable-openssl --enable-libopus --enable-frei0r --enable-libcaca --enable-libquvi --enable-libvidstab --enable-libx265 --enable-libopenjpeg --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1_1/include/openjpeg-1.5 '
  
    libavutil      52. 92.100 / 52. 92.100
  
    libavcodec     55. 69.100 / 55. 69.100
  
    libavformat    55. 48.100 / 55. 48.100
  
    libavdevice    55. 13.102 / 55. 13.102
  
    libavfilter     4. 11.100 /  4. 11.100
  
    libavresample   1.  3.  0 /  1.  3.  0
  
    libswscale      2.  6.100 /  2.  6.100
  
    libswresample   0. 19.100 /  0. 19.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  [concat @ 0x7fcb6c803400] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, concat, from 'audiofiles.txt':
  
    Duration: 00:00:00.00, start: 0.000000, bitrate: 279 kb/s
  
      Stream #0:0: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 280 kb/s
  
  Output #0, ipod, to 'all_audio_edited.m4a':
  
    Metadata:
  
      encoder         : Lavf55.48.100
  
      Stream #0:0: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, 280 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  size= 3020597kB time=26:07:14.44 bitrate= 263.1kbits/s    
  
  video:0kB audio:3004946kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.520849%

• Issue while opening a .mp4 file - CPU shoots up 100%

  16 juillet 2014, par AnilJ

  I am using IMediaWriter, to write out about 20 video frames into an independent .mp4 file and creating a new writer to write a new file. This is a logic (not so efficient one), I’ve used to chunk the web-cam feed into chunks. I am able to successfully able to create multiple .mp4 video files and when opened then in a VLC player, they can be played back.

  However, when I try to open one of the chunked file into a new IContainer object (see below code snippet), my program :

  • Gets stuck at the container.open() call ( see * below), and the CPU
    utilization shoots above 100%.
  • Sometimes it throws an error "moov atom not found", and hence can not open the file.

  In both the cases, my program does not work.

  <code snippet="snippet">
  
          String file = BASE_PATH + File.separator + "output" + File.separator + "output.mp4";  // This is one of the chunk.
  
          IContainer container = IContainer.make();
  
          FileChannel channel = null;
  
  
  
          try {
  
              @SuppressWarnings("resource")
  
              RandomAccessFile inFile = new RandomAccessFile(chunkFile, "r");
  
              channel = inFile.getChannel();
  
          } catch (FileNotFoundException e) {
  
              e.printStackTrace();
  
          }
  
  
  
          // Open up the container
  
  ***        int retval = container.open(channel, IContainer.Type.READ, null);
  
          if (retval &lt; 0) {
  
              // This little trick converts the non friendly integer return value into 
  
              // a slightly more friendly object to get a human-readable error name
  
              IError error = IError.make(retval);
  
              throw new IllegalArgumentException("could not open file: " + mInputFileChannel + "; Error: " + error.getDescription());
  
          }
  
  <code snippet="snippet">
  
  

  Subsequently, I ran the AtomicParsley tool to dump the file content, and it prints following. I am not aware of video file internals and seeking help to know the issue here and potential solution.

  Atom ftyp @ 0 of size: 28, ends @ 28
  
  Atom free @ 28 of size: 8, ends @ 36
  
  Atom mdat @ 36 of size: 45175, ends @ 45211
  
  Atom moov @ 45211 of size: 1052, ends @ 46263
  
       Atom mvhd @ 45219 of size: 108, ends @ 45327
  
       Atom trak @ 45327 of size: 839, ends @ 46166
  
           Atom tkhd @ 45335 of size: 92, ends @ 45427
  
           Atom edts @ 45427 of size: 36, ends @ 45463
  
               Atom elst @ 45435 of size: 28, ends @ 45463
  
           Atom mdia @ 45463 of size: 703, ends @ 46166
  
               Atom mdhd @ 45471 of size: 32, ends @ 45503
  
               Atom hdlr @ 45503 of size: 45, ends @ 45548
  
               Atom minf @ 45548 of size: 618, ends @ 46166
  
                   Atom vmhd @ 45556 of size: 20, ends @ 45576
  
                   Atom dinf @ 45576 of size: 36, ends @ 45612
  
                       Atom dref @ 45584 of size: 28, ends @ 45612
  
                           Atom url  @ 45600 of size: 12, ends @ 45612
  
                   Atom stbl @ 45612 of size: 554, ends @ 46166
  
                       Atom stsd @ 45620 of size: 198, ends @ 45818
  
                           Atom mp4v @ 45636 of size: 182, ends @ 45818
  
                               Atom esds @ 45722 of size: 96, ends @ 45818
  
                       Atom stts @ 45818 of size: 176, ends @ 45994
  
                       Atom stss @ 45994 of size: 24, ends @ 46018
  
                       Atom stsc @ 46018 of size: 28, ends @ 46046
  
                       Atom stsz @ 46046 of size: 100, ends @ 46146
  
                       Atom stco @ 46146 of size: 20, ends @ 46166
  
       Atom udta @ 46166 of size: 97, ends @ 46263
  
           Atom meta @ 46174 of size: 89, ends @ 46263
  
               Atom hdlr @ 46186 of size: 33, ends @ 46219
  
               Atom ilst @ 46219 of size: 44, ends @ 46263
  
                   Atom ©too @ 46227 of size: 36, ends @ 46263
  
                       Atom data @ 46235 of size: 28, ends @ 46263
  
  ------------------------------------------------------
  
  Total size: 46263 bytes; 31 atoms total. AtomicParsley from svn built on Jul 15 2014 (utf8)
  
  Media data: 45175 bytes; 1088 bytes all other atoms (2.352% atom overhead).
  
  Total free atom space: 8 bytes; 0.017% waste.
  
  ------------------------------------------------------

  I am not sure if there is anything wrong with the file itself. Can you please help me understand this ?