[FFmpeg-user] Understanding ffprobe output

Simon Roberts simon at dancingcloudservices.com
Fri Nov 27 20:50:23 EET 2020


Hi all,

I've been making video using the monitor outputs of a pair of Sony A6000
cameras (bypassing the 30 minute limit while gaining other limitations). I
take each camera's output through a splitter, one side goes to a monitor,
and the other to the recording machine.

One camera feeds to a monitor that's only capable of a 60 Hz vertical. The
monitor just says "1080 at 60 Hz". The other camera feeds a different type of
monitor that runs at 30 Hz vertical. (Note, I don't really know what
"vertical" means, frame? field? can't tell. I also don't know if the higher
rate one is running interlaced. I have some vague recollection that I had
noticed hints that it's progressive, but I don't recall what those hints
were)

Anway, everything works, and the recordings are fine. But I noticed that
the file size for the "60 Hz" camera was nearly double that of the other
camera. Both cameras have identical settings internally, and are actually
set at 1080p output.

But these are the outputs of ffprobe on two files made side by side,
"mostly" at a static green screen. The first is the one made with the
higher vertical rate, and the second with the 30 Hz screen. I see the
bitrate difference that correlates to the file sizes, but to my uneducated
eyes they both claim to be "30 fps" (whatever that means--fields? frames?
fairies--I'm certainly doubting my basic knowledge here! :) both say
"progressive" and I see no other differences.

Can anyone help my education?

Many thanks,
Simon

----------------------------------------------------------------
$ ffprobe P-0005-b\ CAM\ 2.mp4
ffprobe version N-98470-g7772666 Copyright (c) 2007-2020 the FFmpeg
developers
  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
  configuration: --prefix=/home/simon/ffmpeg_build
--pkg-config-flags=--static
--extra-cflags='-I/home/simon/ffmpeg_build/include
-I/home/simon/ffmpeg_sources/BMD_SDK/include'
--extra-ldflags=-L/home/simon/ffmpeg_build/lib --extra-libs='-lpthread -lm'
--bindir=/home/simon/bin --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libfreetype --enable-libmp3lame --enable-libopus
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265
--enable-nonfree --enable-decklink
  libavutil      56. 55.100 / 56. 55.100
  libavcodec     58. 95.100 / 58. 95.100
  libavformat    58. 48.100 / 58. 48.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'P-0005-b CAM 2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: iso4avc1isom
    creation_time   : 2020-11-25T19:56:12.000000Z
    com.blackmagic-design.camera.dateRecorded: 2020:11:25
    com.blackmagic-design.camera.timelineID: 00c74876
    com.apple.proapps.clipID: P-0005-b CAM 2
    com.apple.proapps.cameraName: 2
    com.blackmagic-design.camera.uuid: AC427EDA14364C178BABEA7BC35FED1C-2
  Duration: 00:51:16.00, start: 0.000000, bitrate: 28780 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 28647 kb/s, 30 fps, 30
tbr, 30 tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Apple Video Media Handler
      encoder         : H264/AVC
      timecode        : 12:56:11:23
    Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Time Code Media Handler
      timecode        : 12:56:11:23
    Stream #0:2(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Apple Sound Media Handler
      timecode        : 12:56:11:23
Unsupported codec with id 0 for input stream 1
----------------------------------------------------------------
ffprobe version N-98470-g7772666 Copyright (c) 2007-2020 the FFmpeg
developers
  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
  configuration: --prefix=/home/simon/ffmpeg_build
--pkg-config-flags=--static
--extra-cflags='-I/home/simon/ffmpeg_build/include
-I/home/simon/ffmpeg_sources/BMD_SDK/include'
--extra-ldflags=-L/home/simon/ffmpeg_build/lib --extra-libs='-lpthread -lm'
--bindir=/home/simon/bin --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libfreetype --enable-libmp3lame --enable-libopus
--enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265
--enable-nonfree --enable-decklink
  libavutil      56. 55.100 / 56. 55.100
  libavcodec     58. 95.100 / 58. 95.100
  libavformat    58. 48.100 / 58. 48.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'P-0005-b CAM 1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: iso4avc1isom
    creation_time   : 2020-11-25T19:56:12.000000Z
    com.blackmagic-design.camera.dateRecorded: 2020:11:25
    com.blackmagic-design.camera.timelineID: 00c74876
    com.apple.proapps.clipID: P-0005-b CAM 1
    com.apple.proapps.cameraName: 1
    com.blackmagic-design.camera.uuid: AC427EDA14364C178BABEA7BC35FED1C-1
  Duration: 00:51:16.00, start: 0.000000, bitrate: 17868 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 17735 kb/s, 30 fps, 30
tbr, 30 tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Apple Video Media Handler
      encoder         : H264/AVC
      timecode        : 12:56:11:23
    Stream #0:1(eng): Data: none (tmcd / 0x64636D74) (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Time Code Media Handler
      timecode        : 12:56:11:23
    Stream #0:2(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2020-11-25T19:56:12.000000Z
      handler_name    : ?Apple Sound Media Handler
      timecode        : 12:56:11:23
Unsupported codec with id 0 for input stream 1
----------------------------------------------------------------


More information about the ffmpeg-user mailing list