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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 )
 ...


  


• Building ffmpeg iOS libraries for armv7, armv7s, arm64, i386 and universal

  4 février 2015, par sandy

  I have seen several scripts to build FFmpeg API for armv7, 7s and i386 but couldn’t find anything which would work for armv64 as well. Some of the answers on other threads of this forum suggested to prepare a separate library for arm64 but it does not work well with rest of the architectures. Hence I need a script which can work for all the supported architectures for iOS including armv7, armv7s, armv64 and i386.