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• fftools/ffmpeg_opt : update program description to match manpage

  18 décembre 2023, par Anton Khirnov

  fftools/ffmpeg_opt : update program description to match manpage
  Cf. 2244722f1f3
  

  • [DH] fftools/ffmpeg_opt.c

• ffmpeg : zoom a horizontal photo in a vertical video, fill the empty space at the top and bottom with a blurry photo

  23 octobre 2023, par Eugene Khyst

  I'm using ffmpeg to create a vertical video of zoomming a horizontal (landscape) photo.

  


  I want the photo to fit the width of the video, so the top and bottom of the photo need to fill the empty space with the blurry photo :

  


  

  


• In ffmpeg, how do I scale dvdsub subtitles to match video size, using scale2ref filter ?

  24 janvier 2017, par Steve Moseley

  I have an mpeg file, recorded from live TV, containing video and multiple audio and subtitles streams. My eventual goal is to be able to create a smaller video file as the mpeg file is multi-gigabytes in size. My first step on that path is just to be able to select one each of the video, audio and subtitle streams and copy them to an mkv file, discarding the streams I’m not interested in. (I chose mkv as it will allow storing a dvdsub subtitle stream where other container formats wont.)

  The problem I’m having is that the dvdsub subtitles appear very small when I play the output video, when I researched this I found that ffmpeg doesn’t automatically scale the subtitles to match the source video : https://trac.ffmpeg.org/ticket/4744

  I have tried using the scale2ref filter, but I don’t understand the documentation, and the example they give makes no sense to me (see examples below).

  I have a command that selects the three streams and copies 1 minute to the output, as follows :

  ffmpeg -ss 00:28:00.200 -i Hillary-2016-08-21.mpg -t 00:01:00.000 -map 0:0 -c:v copy -map 0:3 -c:a copy -map 0:6 -c:s dvdsub cut.mkv

  Here’s the output :

  Input #0, mpegts, from 'Hillary-2016-08-21.mpg':
  
    Duration: 01:30:00.06, start: 20852.199389, bitrate: 6813 kb/s
  
    Program 1 
  
      Stream #0:0[0xfa]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x12c](eng): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
  
      Stream #0:2[0x131](ita): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired)
  
      Stream #0:3[0x191](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
      Stream #0:4[0x3ea]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:5[0x3ec]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:6[0x3fc](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:7[0x1f40]: Unknown: none ([5][0][0][0] / 0x0005)
  
  File 'cut.mkv' already exists. Overwrite ? [y/N] y
  
  Output #0, matroska, to 'cut.mkv':
  
    Metadata:
  
      encoder         : Lavf57.56.100
  
      Stream #0:0: Video: h264 (Main) (H264 / 0x34363248), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 50 tbr, 1k tbn, 90k tbc
  
      Stream #0:1(eng): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), 384 kb/s
  
      Stream #0:2(eng): Subtitle: dvd_subtitle (dvdsub) (hearing impaired)
  
      Metadata:
  
        encoder         : Lavc57.64.101 dvdsub
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:3 -> #0:1 (copy)
  
    Stream #0:6 -> #0:2 (dvb_subtitle (dvbsub) -> dvd_subtitle (dvdsub))
  
  Press [q] to stop, [?] for help
  
  frame= 2956 fps=0.0 q=-1.0 Lsize=   39612kB time=00:00:59.99 bitrate=5408.7kbits/s speed= 216x    
  
  video:36702kB audio:2896kB subtitle:23kB other streams:0kB global headers:0kB muxing overhead: unknown

  The documentation for scale2ref gives an example with an overlay, and I don’t want to overlay anything, I just want to resize the subtitles stream. Here’s their example :

  'scale2ref[b][a];[a][b]overlay'

  The closest I’ve got is something like this :

  ffmpeg -ss 00:28:00.200 -i Hillary-2016-08-21.mpg -t 00:01:00.000 -map 0:0 -c:v copy -map 0:3 -c:a copy -filter_complex "[0:6]scale2ref[b]" -map "[b]"   cut.mkv

  And the output is :

  Input #0, mpegts, from 'Hillary-2016-08-21.mpg':
  
    Duration: 01:30:00.06, start: 20852.199389, bitrate: 6813 kb/s
  
    Program 1 
  
      Stream #0:0[0xfa]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 50 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x12c](eng): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp
  
      Stream #0:2[0x131](ita): Audio: aac_latm (HE-AAC) ([17][0][0][0] / 0x0011), 48000 Hz, stereo, fltp (visual impaired)
  
      Stream #0:3[0x191](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
      Stream #0:4[0x3ea]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:5[0x3ec]: Unknown: none ([11][0][0][0] / 0x000B)
  
      Stream #0:6[0x3fc](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  
      Stream #0:7[0x1f40]: Unknown: none ([5][0][0][0] / 0x0005)
  
  Streamcopy requested for output stream 0:0, which is fed from a complex filtergraph. Filtering and streamcopy cannot be used together.

  And I don’t really understand how I can use a filter and direct my resized subtitle stream into the output file.

  Any help appreciated ! Thanks !