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• Using ffmpeg to trim HEVC video : correct duration, but output file size too large

  29 novembre 2022, par ddessert

  I have a digitized 8mm 16fps HEVC .mp4 that I'm trying to split into clips using ffmpeg (5.1.2) on MacOS terminal. The output file trims to the correct duration but the filesize is too large.

  


  ffmpeg -ss 05:09 -i input.mp4 -t 02:19 -an -sn -dn -c copy output.mp4


  


  input.mp4 : 11:56 in duration and 8.24 GB in filesize (bitrate 674251 kbits/s).
  
output.mp4 : 02:19 in duration and 5.15 GB in filesize (too large).

  


  5.15 GB is the filesize I'd expect for a clip that is 05:09 + 02:19 in duration at input.mp4's 674251 Kbits/s :
  
(05:09+02:19) * 674251 kbits/sec = 5.16 GB

  


  I've tried various -ss start_pos and -t duration values with similar results. The output file is correctly duration in time and unexpectedly (start_pos+duration)*bitrate in filesize.

  


  I've consulted this ShotStack.io article on trimming with ffmpeg and this ffmpeg wiki section on cutting small sections from files. Neither specifically states that the resulting file size will be trimmed to match the duration of the clip, but I'd think that'd be useful.

  


  Addendum :
  
My input file has only one keyframe at t=0.000s. Likely the root of all my problems.

  


  ffmpeg stdout :

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x14ff04760] Using non-standard frame rate 16384/1024
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    creation_time   : 2021-07-24T11:23:44.000000Z
    encoder         : Lavf58.45.100
  Duration: 00:11:56.13, start: 0.000000, bitrate: 92041 kb/s
  Stream #0:0[0x1](und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709/bt709/unknown, progressive), 5120x3840 [SAR 1:1 DAR 4:3], 91715 kb/s, 16 fps, 16 tbr, 16384 tbn (default)
    Metadata:
      creation_time   : 2021-07-24T11:23:44.000000Z
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      timecode        : 17:15:11:05
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 159 kb/s (default)
    Metadata:
      creation_time   : 2021-07-24T11:23:44.000000Z
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
  Stream #0:2[0x3](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 159 kb/s (default)
    Metadata:
      creation_time   : 2021-07-24T11:23:44.000000Z
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
  Stream #0:3[0x4](eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 2021-07-24T11:23:44.000000Z
      handler_name    : TimeCodeHandler
      timecode        : 17:15:11:05
File 'output.mp4' already exists. Overwrite? [y/N] y
[mp4 @ 0x14ff08660] Using non-standard frame rate 16/1
    Last message repeated 1 times
Output #0, mp4, to 'output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf59.27.100
  Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709/bt709/unknown, progressive), 5120x3840 [SAR 1:1 DAR 4:3], q=2-31, 91715 kb/s, 16 fps, 16 tbr, 16384 tbn (default)
    Metadata:
      creation_time   : 2021-07-24T11:23:44.000000Z
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      timecode        : 17:15:11:05
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame= 4290 fps=0.0 q=-1.0 Lsize= 2988507kB time=00:02:18.93 bitrate=176207.6kbits/s speed= 189x    
video:2988420kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.002924%


  


  ffprobe output.mp4

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x130804080] Using non-standard frame rate 16384/1024
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf59.27.100
  Duration: 00:02:19.31, start: 0.000000, bitrate: 175732 kb/s
  Stream #0:0[0x1](und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709/bt709/unknown, progressive), 5120x3840 [SAR 1:1 DAR 4:3], 91304 kb/s, 16 fps, 16 tbr, 16384 tbn (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      timecode        : 17:15:11:05
  Stream #0:1[0x2](eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      handler_name    : VideoHandler
      timecode        : 17:15:11:05
Unsupported codec with id 0 for input stream 1


  


• converting eac3 to aac with ffmpeg

  30 novembre 2023, par vespino

  I have a number of video files stored on my Synology of which the audio doesn't play on when opening them with DS File. This is because DS File does not support eac3. I would like to convert those files to aac using ffmpeg, but when doing so, all audio is lost.

  


  This is the file info :

  


  Input #0, matroska,webm, from &#x27;<file>.mkv&#x27;:&#xA;  Metadata:&#xA;    encoder         : libebml v1.4.2 &#x2B; libmatroska v1.6.4&#xA;  Duration: 00:48:43.42, start: 0.000000, bitrate: 6566 kb/s&#xA;    Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)&#xA;    Stream #0:1(eng): Audio: eac3, 48000 Hz, 5.1 (default)&#xA;    Stream #0:2(eng): Subtitle: subrip&#xA;    Metadata:&#xA;      title           : English [SDH]&#xA;    Stream #0:3(ara): Subtitle: subrip&#xA;    Metadata:&#xA;      title           : Arabic&#xA;    Stream #0:4(chi): Subtitle: subrip&#xA;</file>

  


  This is my attempt :

  


  ffmpeg -i <file>.mkv -map 0:v -map 0:a:0 -map 0:s -c copy -c:a aac -b:a 640k output.mkv&#xA;</file>

  


  Subtitles are kept, but audio is completely removed. I would like to automate the process if possible.

  


  This is my ffmpeg configuration :

  


  ffmpeg version 4.1.8 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 8.5.0 (GCC)
  configuration: --prefix=/usr --incdir='${prefix}/include/ffmpeg' --arch=i686 --target-os=linux --cross-prefix=/usr/local/x86_64-pc-linux-gnu/bin/x86_64-pc-linux-gnu- --enable-cross-compile --enable-optimizations --enable-pic --enable-gpl --enable-shared --disable-static --disable-stripping --enable-version3 --enable-encoders --enable-pthreads --disable-protocols --disable-protocol=rtp --enable-protocol=file --enable-protocol=pipe --disable-muxer=image2 --disable-muxer=image2pipe --disable-swscale-alpha --disable-ffplay --disable-ffprobe --disable-doc --disable-devices --disable-bzlib --disable-altivec --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libmp3lame --disable-vaapi --disable-cuvid --disable-nvenc --disable-decoder=aac --disable-decoder=aac_fixed --disable-encoder=aac --disable-decoder=amrnb --disable-decoder=ac3 --disable-decoder=ac3_fixed --disable-encoder=zmbv --disable-encoder=dca --disable-decoder=dca --disable-encoder=ac3 --disable-encoder=ac3_fixed --disable-encoder=eac3 --disable-decoder=eac3 --disable-encoder=truehd --disable-decoder=truehd --disable-encoder=hevc_vaapi --disable-decoder=hevc --disable-muxer=hevc --disable-demuxer=hevc --disable-parser=hevc --disable-bsf=hevc_mp4toannexb --x86asmexe=yasm --cc=/usr/local/x86_64-pc-linux-gnu/bin/x86_64-pc-linux-gnu-wrap-gcc --enable-yasm --enable-libx264 --enable-encoder=libx264
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100


  


  Synology does not support eac3 out of the box. So is this even possible ?

  


• ffmpeg, video-clips do not always end at the specified '-to' value

  21 mars 2023, par query-01

  Within the batch file below, I randomly experience a video-clip that will not truncate/end at the value entered for -to . That said, if I have four files joined, then output to output.mp4, at least one file will not end at the specified -to value, yet the other adjoining clips will have complied with their specified -to value.

  


  @echo off
Setlocal EnableDelayedExpansion
Rem "C:\Program Files\Bulk Rename Utility\Bulk Rename Utility.exe" %CD%
for /F "delims=" %%i in ('dir /B /O *.mp4') do (
    set f=%%i
    "C:\Program Files (x86)\VideoLAN\VLC\vlc.exe" "!f!"
    set /p ss="Enter hh:mm:ss: "
    set /p t="Enter Duration: "
    ffmpeg -i "!f!" -ss !ss! -to !t!  -c:v copy -c:a aac _"!f!"
)

for /F "delims=" %%i in ('dir /B /O _*.mp4') do @echo file '%%i' >> clips.txt
set /p fn="Enter A Filename:"
ffmpeg -safe 0 -f concat -i clips.txt -c:v copy -c:a aac !fn!.mp4


  


  All of the video-clips are processed by the original system and remain un_touched before they are handled by this script.

  


  What am I doing incorrectly, and/or, what should I be looking for within the affected video-clip, which would cause this behavior ?

  


  I am using ffmpeg version 2021-11-10-git-44c65c6cc0-full_build-www.gyan.dev on Windows 10 Home, Version : 22H2

  


  Respectfully.