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• Change the Sample/Pixel aspect ratio of video with least possible video re-encoding

  27 août 2022, par PiTao

  I need to have some mp4 videos with square sample (pixel) aspect ratio (1:1) i.e. square pixels. However, as ffprobe shows my video has PAR of 59:54.

  


  I have tried using this command :

  


  ffmpeg  -i in.mp4 -c copy -bsf:v "h264_metadata=sample_aspect_ratio=1/1" out.mp4


  


  but still the PAR has not changed in my downstream applicaiton or as I checked it with the ffprobe :

  


  ffprobe version n5.1 Copyright (c) 2007-2022 the FFmpeg developers
  built with gcc 12.1.1 (GCC) 20220730
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-shared --enable-version3
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'vimeo_11261121.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf59.27.100
  Duration: 00:00:52.36, start: 0.000000, bitrate: 519 kb/s
  Stream #0:0[0x1](eng): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p(progressive), 720x576 [SAR 1:1 DAR 5:4], 382 kb/s, SAR 59:54 DAR 295:216, 25 fps, 25 tbr, 12800 tbn (default)
    Metadata:
      handler_name    : Apple Video Media Handler
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 130 kb/s (default)
    Metadata:
      handler_name    : Apple Sound Media Handler
      vendor_id       : [0][0][0][0]


  


  If I not mistaken, the ffmpeg only changes the metadata and not the actual PAR. Is it possible to change the PAR (sample aspect ratio) preferably without much re-encoding ?

  


• How can I pass a hh:mm:ss.mmm timestamp to ffmpeg's trim filter arguments ? [closed]

  21 août 2022, par Jason Gross

  According to the documentation, 11.256 trim :

  


  


  start, end, and duration are expressed as time duration specifications ; see (ffmpeg-utils)the Time duration section in the ffmpeg-utils(1) manual for the accepted syntax.

  


  


  The linked manual section says :

  


  


  2.3 Time duration

  


  There are two accepted syntaxes for expressing time duration.

  


  [-][HH:]MM:SS[.m...]


  


  HH expresses the number of hours, MM the number of minutes for a maximum of 2 digits, and SS the number of seconds for a maximum of 2 digits. The m at the end expresses decimal value for SS.

  


  or

  


  [-]S+[.m...][s|ms|us]


  


  S expresses the number of seconds, with the optional decimal part m. The optional literal suffixes ‘s’, ‘ms’ or ‘us’ indicate to interpret the value as seconds, milliseconds or microseconds, respectively.

  


  In both expressions, the optional ‘-’ indicates negative duration.

  


  


  ---

  


  However, if I write ffmpeg -i input.mp4 -filter_complex "[0:v]trim=start=00:09:15.000[outv]" -map '[outv]:v' -an output.mp4, I get a 9 second long output clip, apparently interpreting : as an argument separator and interpreting the subsequent 09 as the end argument (no idea what it interprets the 15 as). How do I get ffmpeg to treat the argument to start as a timestamp rather than splitting it at : ?

  


  ---

  


  If it's relevant :

  


  $ ffmpeg -h
ffmpeg version 4.2.7-0ubuntu0.1 Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: --prefix=/usr --extra-version=0ubuntu0.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Hyper fast Audio and Video encoder


  


• ffmpeg save video in segments, time does not match

  22 août 2022, par Yohann

  I use ffmpeg to save the rtsp live stream to the local, specify the fragment size of 2 seconds and use the current time to name the video file

  


  But the length of the returned video is not equal to 2 seconds and the interval between file names is not 2 seconds

  


  I have tried several command line arguments

  


  ffmpeg -i rtsp://192.168.18.119/live/test -f segment -strftime 1 -segment_time 2 -segment_atclocktime 1 -reset_timestamps 1 -an -vcodec copy ./%Y-%m-%d-%H.%M.%S.mp4

# execute result
2022-08-22-17.20.16.mp4  duration：00:03
2022-08-22-17.20.17.mp4  duration：00:03
2022-08-22-17.20.18.mp4  duration：00:07
2022-08-22-17.20.19.mp4  duration：00:03
2022-08-22-17.20.20.mp4  duration：00:03
# file names are not time aligned


  


  ffmpeg -i rtsp://192.168.18.119/live/test -f segment -strftime 1 -segment_time 2 -reset_timestamps 1 -an -vcodec copy ./%Y-%m-%d-%H.%M.%S.mp4

# execute result
2022-08-22-17.42.36.mp4 duration：00:03
2022-08-22-17.42.37.mp4 duration：00:03
2022-08-22-17.42.41.mD4 duration：00:03
2022-08-22-17.42.44.mp4 duration：00:03
2022-08-22-17.42.48.mp4 duration：00:03
2022-08-22-17.42.51.mp4 duration：00:03
# file names are not time aligned


  


  Expect to generate video

  


  2022-08-22-17.50.00.mp4 时长：00:02
2022-08-22-17.50.02.mp4 时长：00:02
2022-08-22-17.50.04.mD4 时长：00:02
2022-08-22-17.50.06.mp4 时长：00:02
2022-08-22-17.50.08.mp4 时长：00:02
2022-08-22-17.50.10.mp4 时长：00:02
...