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• How to find transitions in a DVD ?

  6 juin 2019, par Conrad C

  I am watching instructional videos on a mp4 and I want to find the time at which each new instruction/chapter starts. Every time a new instruction is show, it is preceded with a transition video animation ex :" Instruction #3...."
  I tried this command :

  ffmpeg -i HowToCook.mp4 -filter:v "select='gt(scene,0.7)',showinfo" -f null - 2> ffout2

  But this doesn’t work, and it gives me the times everytime the camera man moves the camera. It doesn’t seem to work on transitions. Is there another command that could work better ?

• Audio is lost on transcoding from DTS to AAC

  18 octobre 2015, par cirko

  On a Synology drive, I’m trying to transcode audio in an .MKV file from DTS to AAC using the native ffmpeg encoder. But without any error message (at least I don’t recognize any here), the audio stream is just missing in the output files. I tried it on several different files, all with the same result, leading to the conclusion that either I’m unable to see the error or something’s wrong with FFMPEG. I used the standard FFMPEG package provided with OPKG.
  This is the output I usually get :

  CirkosDaten> ffmpeg -i encodertest.mkv -map 0 -c:v copy -c:s copy -c:a aac 
  
  -strict experimental output.mkv
  
  ffmpeg version 2.0.2 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jun  3 2015 06:25:48 with gcc 4.6.4 (Marvell GCC release 
  
  20150204-c4af733b 64K MAXPAGESIZE ALIGN CVE-2015-0235)
  
    configuration: --prefix=/usr/syno --incdir='${prefix}/include/ffmpeg' 
  
  --arch=arm --target-os=linux --cross-prefix=/usr/local/arm-marvell-linux-
  
  gnueabi/bin/arm-marvell-linux-gnueabi- --enable-cross-compile --enable-
  
  optimizations --enable-pic --enable-gpl --enable-shared --disable-static 
  
  --enable-version3 --enable-nonfree --enable-libfaac --enable-encoders 
  
  --enable-pthreads --disable-bzlib --disable-protocol=rtp --disable-
  
  muxer=image2 --disable-muxer=image2pipe --disable-swscale-alpha --disable-
  
  ffserver --disable-ffplay --disable-devices --disable-bzlib --disable-
  
  altivec --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-
  
  libmp3lame --disable-vaapi --disable-decoder=amrnb --disable-encoder=zmbv 
  
  --disable-encoder=dca --disable-encoder=ac3 --disable-encoder=ac3_fixed 
  
  --disable-encoder=eac3 --disable-decoder=dca --disable-decoder=eac3 
  
  --disable-decoder=truehd --cc=/usr/local/arm-marvell-linux-gnueabi/bin/arm-
  
  marvell-linux-gnueabi-ccache-gcc
  
  
  
    libavutil      52. 38.100 / 52. 38.100
  
    libavcodec     55. 18.102 / 55. 18.102
  
    libavformat    55. 12.100 / 55. 12.100
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 79.101 /  3. 79.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Guessed Channel Layout for  Input Stream #0.1 : 5.1
  
  Guessed Channel Layout for  Input Stream #0.2 : 5.1
  
  Input #0, matroska,webm, from 'encodertest.mkv':
  
    Metadata:
  
      title           : encodingtest
  
      creation_time   : 2012-09-23 09:38:19
  
    Duration: 00:01:00.94, start: 0.000000, bitrate: 9624 kb/s
  
      Chapter #0.0: start 0.000000, end 55.347000
  
      Metadata:
  
        title           : 00:00:00.000
  
      Chapter #0.1: start 55.347000, end 60.936000
  
      Metadata:
  
        title           : 00:04:56.171
  
      Stream #0:0: Video: h264 (High), yuv420p, 1920x816 [SAR 1:1 DAR 40:17], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
  
      Metadata:
  
        title           : encodingtest
  
      Stream #0:1(ger): Audio: dts, 48000 Hz, 5.1 (default)
  
      Metadata:
  
        title           : DTS
  
      Stream #0:2(eng): Audio: dts, 48000 Hz, 5.1
  
      Metadata:
  
        title           : DTS
  
      Stream #0:3(ger): Subtitle: subrip (default)
  
      Metadata:
  
        title           : Forced Subs
  
  Output #0, matroska, to 'output.mkv':
  
    Metadata:
  
      title           : encodingtest
  
      encoder         : Lavf55.12.100
  
      Chapter #0.0: start 0.000000, end 55.347000
  
      Metadata:
  
        title           : 00:00:00.000
  
      Chapter #0.1: start 55.347000, end 60.936000
  
      Metadata:
  
        title           : 00:04:56.171
  
      Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p, 1920x816 [SAR 1:1 DAR 40:17], q=2-31, 23.98 fps, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        title           : encodingtest
  
      Stream #0:1(ger): Subtitle: subrip (default)
  
      Metadata:
  
        title           : Forced Subs
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:3 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame= 1461 fps=528 q=-1.0 Lsize=   54636kB time=00:01:00.81 bitrate=7360.1kbits/s    
  
  video:54624kB audio:0kB subtitle:0 global headers:0kB muxing overhead 
  
  0.023249%encodingtest

  When I additionally set the bitrate, the output says

  Codec AVOption b (set bitrate (in bits/s)) specified for output file #0 
  
  (output.mkv) has not been used for any stream. The most likely reason is 
  
  either wrong type (e.g. a video option with no video streams) or that it is 
  
  a private option of some encoder which was not actually used for any stream.

  This indicates that somehow the 5.1, 48kHz DTS stream isn’t considered as an input. Why ?

  EDIT : Is it possible that DTS decoding is turned off somewhere here ? I reckoned maybe that’s why I get no errors. But I didn’t see any obvious option for that in the output.

• avformat/mov : Add option to ignore chapters during parsing

  10 novembre 2015, par Bryan Huh

  avformat/mov : Add option to ignore chapters during parsing
  Chapter-indexing can be expensive since chapters may be interspersed
  
  throughout the entire file and may require many seeks - especially
  
  costly when consuming a video over a remote protocol like http.
  
  Furthermore it is often unnecessary, especially when only trying to get
  
  video info (e.g. via ffprobe).
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c