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• How does ffprobe determine duration ?

  10 janvier 2019, par jasongullickson

  I’m using ffprobe to analyze media files stored on a remote server. This seems to work well, but for some files the duration is missing or incorrect (usually longer than it should be). Other times it returns this information accurately, and it doesn’t seem to be related to the media type (codec, etc.).

  Here’s an example of a command that works :

  ffprobe -v quiet -print_format json -show_streams -show_format http://host.com/file.aiff

  {
  
  "streams": [
  
      {
  
          "index": 0,
  
          "codec_name": "pcm_s16be",
  
          "codec_long_name": "PCM signed 16-bit big-endian",
  
          "codec_type": "audio",
  
          "codec_time_base": "1/44100",
  
          "codec_tag_string": "[0][0][0][0]",
  
          "codec_tag": "0x0000",
  
          "sample_fmt": "s16",
  
          "sample_rate": "44100",
  
          "channels": 2,
  
          "bits_per_sample": 16,
  
          "r_frame_rate": "0/0",
  
          "avg_frame_rate": "0/0",
  
          "time_base": "1/44100",
  
          "start_pts": 0,
  
          "start_time": "0.000000",
  
          "duration_ts": 8494248,
  
          "duration": "192.613333",
  
          "bit_rate": "1411200",
  
          "nb_frames": "8494248",
  
          "disposition": {
  
              "default": 0,
  
              "dub": 0,
  
              "original": 0,
  
              "comment": 0,
  
              "lyrics": 0,
  
              "karaoke": 0,
  
              "forced": 0,
  
              "hearing_impaired": 0,
  
              "visual_impaired": 0,
  
              "clean_effects": 0,
  
              "attached_pic": 0
  
          }
  
      }
  
  ],
  
  "format": {
  
      "filename": "http://host.com/file.aiff",
  
      "nb_streams": 1,
  
      "nb_programs": 0,
  
      "format_name": "aiff",
  
      "format_long_name": "Audio IFF",
  
      "start_time": "0.000000",
  
      "duration": "192.613333",
  
      "probe_score": 100
  
  }
  
  }

  Here’s an example of one that doesn’t :

  ffprobe -v quiet -print_format json -show_streams -show_format "http://host.com/file.wav"

  Which generates this result :

  {
  
  "streams": [
  
      {
  
          "index": 0,
  
          "codec_name": "pcm_s16le",
  
          "codec_long_name": "PCM signed 16-bit little-endian",
  
          "codec_type": "audio",
  
          "codec_time_base": "1/44100",
  
          "codec_tag_string": "[1][0][0][0]",
  
          "codec_tag": "0x0001",
  
          "sample_fmt": "s16",
  
          "sample_rate": "44100",
  
          "channels": 2,
  
          "bits_per_sample": 16,
  
          "r_frame_rate": "0/0",
  
          "avg_frame_rate": "0/0",
  
          "time_base": "1/44100",
  
          "bit_rate": "1411200",
  
          "disposition": {
  
              "default": 0,
  
              "dub": 0,
  
              "original": 0,
  
              "comment": 0,
  
              "lyrics": 0,
  
              "karaoke": 0,
  
              "forced": 0,
  
              "hearing_impaired": 0,
  
              "visual_impaired": 0,
  
              "clean_effects": 0,
  
              "attached_pic": 0
  
          }
  
      }
  
  ],
  
  "format": {
  
      "filename": "http://host.com/file.wav",
  
      "nb_streams": 1,
  
      "nb_programs": 0,
  
      "format_name": "wav",
  
      "format_long_name": "WAV / WAVE (Waveform Audio)",
  
      "bit_rate": "1411200",
  
      "probe_score": 99
  
  }
  
  }

  These two examples are different formats, but I’ve seen it work and not work when the format is the same, I just don’t have an example handy.

  What I’d like to know is if there is something I can change about the parameters I’m using with ffprobe to allow the duration to be determined consistently and accurate, or any information I can find as to how ffprobe works so I figure out how I might change the input files, etc. so they work correctly.

  Alternatively, if there is a different tool that works more reliably (it would need to be an open-source Linux tool) any suggestions or recommendations are welcome.

• How to determine webm duration using ffprobe

  23 août 2021, par Lopakhin

  My goal is simple , I have several webm files need to be concated, but first I need to determine their durations.

  



  It seems webm file are played as streams, so there is no way to tell the length of each file.

  



  I have been using ffprobe to do the job ,but the duration returned is N/A.The command I use was :

  



  ffprobe -i input.file -show_format | grep duration


  



  thanks.

  



  The complete output of ffprobe list below :

  



   ffprobe version 2.6.2 Copyright (c) 2007-2015 the FFmpeg developers
  built with Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.6.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc --enable-libxvid --enable-libtheora --enable-libvorbis --enable-libvpx --enable-vda
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, matroska,webm, from '231':
  Metadata:
    encoder         : GStreamer matroskamux version 1.5.91
    creation_time   : 2015-12-05 07:59:29
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 14.99 fps, 14.99 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      title           : Video
    Stream #0:1(eng): Audio: vorbis, 48000 Hz, stereo, fltp (default)
    Metadata:
      title           : Audio
duration=N/A


  


• ffmpeg trim mp3 - determine precisely the start and end times of section to be trimmed

  4 février 2019, par Ahmed Khalil

  I have a long mp3 track of an audio book (more than 9 hours long) that I would like to trim using ffmpeg.

  The sample code below is used to trim an mp3 section by providing the start and end times. However, when I determine the start and end times, then checking the output file, it’s not as precisely as I want, sometimes several minutes ahead/before the desired point.

  import subprocess
  
  file = r'audio book.mp3'
  
  track_name = "trimmed section"
  
  output = r'D:\{0}'.format(track_name)
  
  start = '01:26:04'
  
  end = '01:33:17'
  
  
  
  d = subprocess.getoutput('ffmpeg -i "{0}" -ss {1} -to {2} -c copy {3}.mp3"'
  
                       .format(file, start, end, output))
  
  
  
  print(d)

  Is there a way to determine with accuracy the real start and end time of an mp3 audio track, to be given afterwards as inputs to the code...to trim the desired sections all at once, without the need to adjust/fine-tune the start and end time manually ??