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• 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.

• avcodec/mpegvideo : Change mpeg2 unquant to work with higher precission qscale

  17 septembre 2015, par Michael Niedermayer

  avcodec/mpegvideo : Change mpeg2 unquant to work with higher precission qscale
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mips/mpegvideo_init_mips.c
  • [DH] libavcodec/mpegvideo.c
  • [DH] libavcodec/x86/mpegvideo.c

• How to compare images to find the least blurry image ?

  31 octobre 2022, par Frezzley

  How to compare images to find the least blurry image ?

  



  I want to automaticallz generate an image/thumbnail from a video.

  



  I use ffmpg for that.

  



  However once in a while the image is totally blurred and I want to get rid of the blurry images.

  



  My idea was to create multiple images per video and than compare the images to eachother.

  



  Now the question :

  



  Is there a way to compare the blurryness of images ?