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• FFPROBE get start-time of audio only

  13 février 2023, par Marcus

  I am using this to get the start time of the video and audio :

  


  ffprobe -show_entries stream=start_time -i https://www.website.com/video.mp4


  


  And the response I get is :

  


      ffprobe version 4.3.1 Copyright (c) 2007-2020 the FFmpeg developers
      built with Apple clang version 12.0.0 (clang-1200.0.32.28)
      configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --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 --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack
      libavutil      56. 51.100 / 56. 51.100
      libavcodec     58. 91.100 / 58. 91.100
      libavformat    58. 45.100 / 58. 45.100
      libavdevice    58. 10.100 / 58. 10.100
      libavfilter     7. 85.100 /  7. 85.100
      libavresample   4.  0.  0 /  4.  0.  0
      libswscale      5.  7.100 /  5.  7.100
      libswresample   3.  7.100 /  3.  7.100
      libpostproc    55.  7.100 / 55.  7.100
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://www.website.com/video.mp4':
      Metadata:
        major_brand     : isom
        minor_version   : 512
        compatible_brands: isomiso2avc1mp41
        encoder         : Lavf58.76.100
      Duration: 00:03:14.85, start: 0.000000, bitrate: 4488 kb/s
        Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 4418 kb/s, 24 fps, 24 tbr, 90k tbn, 48 tbc (default)
        Metadata:
          handler_name    : VideoHandler
        Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 69 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
[STREAM]
start_time=0.000000
[/STREAM]
[STREAM]
start_time=9.892993
[/STREAM]


  


  How can I get only the second stream, which is the audio, and without all the extra info ?

  


  So the response would just be :

  


  


  start_time=9.892993

  


  


• av_hwdevice_iterate_types returns an empty list

  9 juillet 2020, par Ruslan Ablyazov

  I used an example https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/hw_decode.c

  


  The av_hwdevice_iterate_types function returns an empty list. What could be the reason ?

  


  And avcodec_find_decoder_by_name("h264_cuvid") returns NULL.

  


  FFmpeg version :

  


  ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --enable-gpl --enable-ladspa --enable-libpulse --enable-libsoxr --enable-libspeex --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-nonfree --disable-ffplay --enable-libxvid --enable-cuda --enable-cuda-nvcc --enable-cuvid --enable-nvenc --enable-nonfree --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100


  


  The command ffmpeg -c:v h264_cuvid -i 7.mp4 71.mp4 outputs :

  


  ...
Stream mapping:
Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (libx264))
....


  


  And it works.

  


  The command ffmpeg-hwaccel cuda-i 7.mp4 71.mp4 outputs :

  


  ...
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
....


  


  The command ffmpeg -codecs outputs :

  


   ...
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_v4l2m2m h264_cuvid ) (encoders: libx264 libx264rgb h264_nvenc h264_v4l2m2m nvenc nvenc_h264 )
 D.VIL. hap                  Vidvox Hap
 DEV.L. hevc                 H.265 / HEVC (High Efficiency Video Coding) (decoders: hevc hevc_v4l2m2m hevc_cuvid ) (encoders: libx265 nvenc_hevc hevc_nvenc hevc_v4l2m2m )
 ...


  


• Add support for playing Audible AAXC (.aaxc) files [PATCH v4]

  1er janvier 2000, par Vesselin Bontchev

  Add support for playing Audible AAXC (.aaxc) files [PATCH v4]
  The AAXC container format is the same as the (already supported) Audible
  
  AAX format but it uses a different encryption scheme.
  Note : audible_key and audible_iv values are variable (per file) and are
  
  externally fed.
  It is possible to extend https://github.com/mkb79/Audible to derive the
  
  audible_key and audible_key values.
  Relevant code :
  def decrypt_voucher(deviceSerialNumber, customerId, deviceType, asin, voucher) :
  
      buf = (deviceType + deviceSerialNumber + customerId + asin).encode("ascii")
  
      digest = hashlib.sha256(buf).digest()
  
      key = digest[0:16]
  
      iv = digest[16 :]
      # decrypt "voucher" using AES in CBC mode with no padding
  
      cipher = AES.new(key, AES.MODE_CBC, iv)
  
      plaintext = cipher.decrypt(voucher).rstrip(b"\x00")  # improve this !
  
      return json.loads(plaintext)
  The decrypted "voucher" has the required audible_key and audible_iv
  
  values.
  Update (Nov-2020) : This patch has now been tested by multiple folks -
  
  details at the following URL :
  https://github.com/mkb79/Audible/issues/3
  Signed-off-by : Vesselin Bontchev <vesselin.bontchev@yandex.com>
  

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