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• ffmpeg audio/video sync problems when uploading to WhatsApp

  11 janvier 2021, par Luke Collins

  (Note : I have looked at related questions such as this one, but the solutions there didn't work for me since presumably their output files wouldn't play correctly in mpv, whereas mine do.)

  


  I want to send a scene from a film to my friend on WhatsApp. I run

  


  


  ffmpeg -i film.mp4 -ss 00:25:30 -t 00:03:00 -c: copy out.mp4

  


  


  to extract the clip, which produces the file out.mp4 which plays fine when I play it with mpv.

  


  If instead, I play the file in my browser (firefox), the first frame is static for a couple of seconds while audio plays, until the video starts and the video and audio are both in sync. (In other words, it seems the file has additional unnecessary audio information appended to the beginning of the file, which starts before my desired clip when played in firefox).

  


  Diagrammatically, I suspect the video contains the following information :

  


  

  


  and firefox plays it in this way :

  


  

  


  What's worse is that when I upload it to WhatsApp, it misaligns the audio with the video, instead playing it this way :

  


  

  


  How can I fix this so that the video has no additional video/audio information ?

  


  I appreciate any help with this.

  


• FFmpeg subtitle filter set start time

  31 décembre 2020, par CasualDemon

  I am trying to burn-in subtitles for a shorter section of a video, but using the subtitles filter always starts from the beginning of the subtitle stream, not at the specified start time, even when copying from the same video.

  


  So for example if I start an encode 10 minutes in to a film, the video will properly be set from there, but the subtitles will start from the beginning (10 minute offset in this case).

  


  ffmpeg -y -ss 600.0 -to 660.0 -i movie.mkv -filter_complex "[0:0]subtitles='movie.mkv':si=1[v]" -map "[v]" -c:v libx265 -crf 22 output.mkv


  


  This is not a problem when using picture based subtitles and the overlay filter, such as :

  


  -filter_complex "[0:0][0:2]overlay[v]"


  


  It seems to only affect text based subtitles. I don't know if this is just not possible and will require another solution, or if I am approaching it wrong. Any help is appreciated !

  


• ffmpeg change metadata inside video file

  26 novembre 2020, par virtualsets

  Hello I have problems to change timecode insdie metadata of a video file "mov"

  


  ruta=r"E:\Brutos-sin-eliminar\inma-ruben-22-2-2020\multicam\\"
nombre=r"A019_02230134_C186.mov"
comand="ffmpeg -i " + nombre + " -ss 0 -map 0 -acodec copy -vcodec copy -timecode 01:20:10:00 -metadata:s:2:0 timecode=01:20:10:00 -metadata:s:1:0 timecode=01:20:10:00 -metadata:s:0:2 -metadata:s:0:2  timecode=01:10:10:00"+ " convert_" + nombre

os.popen(comand)


  


  I need to put muy own timecode to the file but this command not works.

  


  The console give me

  


    mov @ 00000225287fdc00] You requested a copy of the original timecode track so timecode metadata are now ignored
Output #0, mov, to 'convert_A019_02230134_C186.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537199360
    compatible_brands: qt  
    com.blackmagic-design.camera.windowedSensor: 1
    com.apple.proapps.manufacturer: Blackmagic Design
    com.blackmagic-design.camera.uuid: 3cf1dd9e-e307-47ff-864e-5487fea3fa47
    com.blackmagic-design.camera.projectFPS: 25
    com.apple.proapps.shootingRate: 50
    com.blackmagic-design.camera.cameraType: Blackmagic Pocket Cinema Camera 4K
    com.blackmagic-design.camera.shutterAngle: 180°
    com.blackmagic-design.camera.shutterMode: Angle
    com.blackmagic-design.camera.iso: 3200
    com.blackmagic-design.camera.whiteBalanceKelvin: 3000
    com.blackmagic-design.camera.whiteBalanceTint: -44
    com.apple.proapps.customgamma: com.blackmagic-design.camera.filmlog
    com.blackmagic-design.camera.look.LUTName: Blackmagic Pocket 4K Film to Extended Video.cube
    com.blackmagic-design.camera.guides.aspectRatio: 2:1
    com.blackmagic-design.camera.guides.safeArea: 90
    com.blackmagic-design.camera.firmware: 6.6
    com.apple.proapps.clipID: A019_02230134_C186
    com.apple.proapps.reel: 19
    com.apple.proapps.scene: 1
    com.apple.proapps.shot: 99
    com.apple.proapps.isGood: 0
    com.blackmagic-design.camera.environment: interior
    com.blackmagic-design.camera.dayNight: day
    com.apple.proapps.cameraName: A
    com.blackmagic-design.camera.colorScience: Blackmagic Pocket Cinema Camera 4K, Color Science Gen 4
    com.blackmagic-design.camera.dateRecorded: 2020:02:23
    timecode        : 01:20:10:00
    encoder         : Lavf58.11.101
    Stream #0:0(eng): Video: prores (apcn / 0x6E637061), yuv422p10le(bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 122315 kb/s, 25 fps, 25 tbr, 12800 tbn, 25 tbc (default)
    Metadata:
      creation_time   : 01:10:10:00
      handler_name    : ?Apple Alias Data Handler
      encoder         : Apple ProRes 422
      timecode        : 01:10:10:00
    Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2020-02-23T00:34:02.000000Z
      handler_name    : ?Apple Alias Data Handler
      timecode        : 01:20:10:00
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
    Metadata:
      creation_time   : 2020-02-23T00:34:02.000000Z
      handler_name    : ?Apple Alias Data Handler
      timecode        : 01:20:10:00
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)
Press [q] to stop, [?] for help
frame=  467 fps=0.0 q=-1.0 Lsize=  281452kB time=00:00:18.64 bitrate=123693.3kbits/s speed=71.1x    
video:278913kB audio:2531kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.002533%


  


  I dont understand why not modificate the mov file... when open the metadata it is oringinal.

  


  Reggards