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• Anomalie #2020 : Rendre optionnelles les extensions

  28 octobre 2014, par RastaPopoulos ♥

  Est-ce qu’on peut faire un tableau de ce genre de fonctions/filtres/boucles, quand on en trouve, en listant d’un côté où elles sont appelées dans le core et à côté où elles se trouvent dans les plugins-dist ? Sur le wiki, ou framapad, ou un article non publié sur spip.net, ou ici ?

  Ou autre question, est-ce qu’il y a une procédure pour les trouver, ou bien est-ce qu’on les voit au petit bonheur la chance en enlevant les extensions et en navigant au hasard dans les pages ?

  Ça permettrait de s’en rappeler, de ne pas avoir à les re-rechercher quand on y repense plus tard, et de pouvoir éventuellement corriger au fur et à mesure (du genre "tiens aujourd’hui je corrige telle fonction").

• 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


  


• Is there an efficient way to use ffmpeg to perform a large quantity of cuts from a single file ?

  16 mars 2024, par Giuliano Oliveri

  I'm trying to cut video files into smaller chunks. (each one being one word said in the video, so they're not all of equal size)

  


  I've tried a lot of different approaches to try to be as efficient as possible, but I can't get the runtime to be under 2/3rd of the original video length. That's an issue because I'm trying to process 400+ hours of video.

  


  Is there a more efficient way to do this ? Or am I doomed to run this for weeks ?

  


  Here is the command for my best attempt so far

  


  ffmpeg -hwaccel cuda -hwaccel_output_format cuda -ss start_timestamp -t to_timestamp -i file_name -vf "fps=30,scale_cuda=1280:720" -c:v h264_nvenc -y output_file


  


  Note that the machine running the code has a 4090
This command is then executed via python, which gives it the right timestamps and file paths for each smaller clip in a for loop

  


  I think it's wasting a lot of time calling a new process each time, however I haven't been able to get better results with a split filter ; but here's the ffmpeg-python code for that attempt :

  


  Creation of the stream :

  


  inp = (
    ffmpeg
    .input(file_name, hwaccel="cuda", hwaccel_output_format="cuda")
    .filter("fps",fps=30)
    .filter('scale_cuda', '1280','720')
    .filter_multi_output('split')
)


  


  Which then gets called in a for loop

  


  (
    ffmpeg
    .filter(inp, 'trim', start=row[1]['start'], end=row[1]['end'])
    .filter('setpts', 'PTS-STARTPTS')
    .output(output_file,vcodec='h264_nvenc')
    .run()
)