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• lavc/vvc : Ensure subpictures don't overlap

  22 février, par Frank Plowman

  lavc/vvc : Ensure subpictures don't overlap
  This is essentially a re-implementation of
  
  https://patchwork.ffmpeg.org/project/ffmpeg/patch/20241005223955.54158-1-post@frankplowman.com/
  That patch was not applied last time.  Instead we opted to identify
  
  issues which could be caused by invalid subpicture layouts and remedy
  
  those issues where they manifest, either through error detection or code
  
  hardening.  This was primarily implemented in the set
  
  https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=13381.
  This has worked to some degree, however issues with subpicture layouts
  
  continue to crop up from the fuzzer and I've fixed a number of bugs
  
  related to subpicture layouts since then.  I think it's best to return
  
  to the initial plan and simply check if the subpicture layout is valid
  
  initially.
  This implementation is also lighter than the first time — by doing a
  
  bit more logic in pps_subpic_less_than_one_tile_slice, we are able to
  
  store a tile_in_subpic map rather than a ctu_in_subpic map.  This
  
  reduces the size of the map to the point it becomes possible to allocate
  
  it on the stack.  Similar to 8bd66a8c9587af61c7b46558be3c4ee317c1af5a,
  
  the layout is also validated in the slice map construction code, rather
  
  than in the CBS, which avoids duplicating some logic.
  Signed-off-by : Frank Plowman <post@frankplowman.com>
  

  • [DH] libavcodec/vvc/ps.c

• image sequence to Video. Faster Way to Render "Hold" frames in FFMPEG (without duplicating image)

  11 septembre 2014, par dprogramz

  I’m working on a project that converts a Flash Movie with dynamic input to Apple Animation Codec.

  It’s to generate messaging, so there is some animation, then the message holds, then animation resumes, etc. The hold times are user variable.

  I’m first converting the SWF to PNGs by sending a bitstream via the actionscript3 PNGEncoder library, and using a PHP script to save the bitstream to the server as a series of temp png files. This is working very fast.

  from flash ill get an image sequence like this :

  frame000.png-frame014.png

  frame0200.png-frame250.png

  frame350.png-frame400.png

  frames 15-199 are all the same image holding. I’m not sending bitstreams for the holding images to save bandwidth and time, it would be redundant to send the same image file 185 times. Right now I am copying frame14.png with incrementing file numbers. I have to do this for each instance there is a hold frame.

  After all the hold frame holes are filled I then run FFMPEG on the complete image sequence to generate the video.

  Is there any faster way to do this ? The longer the hold (which is variable by the user) the longer it takes to render. I understand that there will be some extra render time, but it’s a repeated image and in other conversion programs does not take nearly as long. Or is my current way of doing it the only way in this instance ?

  When rendering out of a program like after effects, the animation codec seems to dynamically adjust the frame rate for hold frames.

  Thanks for the help and insight !!

• ffmpeg combine files where first has no audio mutes entire ouput

  1er mars 2017, par rodrigo-silveira

  I have multiple ts files that I need to combine before transcoding. Typically, I just sort the list of files, then concat them. Works great — in most cases.

  The problem

  The first file in the series of ts files has no audio. The second file does have audio (as do all of the subsequent files in this list). The output is a file with all of the video combined, but zero audio throughout.

  How can I combine multiple video files and preserve the audio of the files with audio ?

  $: ffmpeg -i file-01.ts
  
  
  
  Input #0, mpegts, from 'file-01.ts':
  
    Duration: 00:03:18.63, start: 11.743000, bitrate: 2044 kb/s
  
    Program 1 
  
      Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
  
  
  
  
  
  $: ffmpeg -i file-02.ts
  
  
  
  Input #0, mpegts, from 'file-02.ts':
  
    Duration: 00:00:10.02, start: 23124.795000, bitrate: 2251 kb/s
  
    Program 1 
  
      Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
  
      Stream #0:1[0x101](und): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 155 kb/s
  
  
  
  
  
  $: cat file-01.ts file-02.ts > out-01.ts
  
  $: ffmpeg -i file-01.ts -i file-02.ts -c:v copy -c:a copy out-02.ts

  In the first case (cat [files] > out) out-01.ts has the videos in the right order, and zero audio. In the second case (ffmpeg [-i files] out) I only get the video from the first file, with the audio from the second on top. No video from the subsequent files. I’ve also tried that command with/without -c:a copy and -c:v copy.