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• avcodec/ttmlenc : add initial support for regions and styles

  29 mars 2021, par Jan Ekström

  avcodec/ttmlenc : add initial support for regions and styles
  Attempts to utilize the TTML cell resolution as a mapping to the
  
  reference resolution, and maps font size to cell size. Additionally
  
  sets the display and text alignment according to the ASS alignment
  
  number.
  Signed-off-by : Jan Ekström <jan.ekstrom@24i.com>
  

  • [DH] libavcodec/ttmlenc.c
  • [DH] libavcodec/ttmlenc.h
  • [DH] tests/ref/fate/sub-ttmlenc

• Audio issues when overlaying two videos (ffmpeg)

  4 août 2021, par crashyourtesla

  I'm trying to overlay a short 10 second video on top of a 2 minute video and have the 10 second video show up at the 30 second mark. Here is what I have so far

  


  start = 30
subprocess.run(
    f'ffmpeg -y \
        -i {os.path.join(path, "2minutevideo.mp4")} \
        -i {os.path.join(path, "popup.mov")} \
        -filter_complex \
        "[0:v]setpts=PTS-STARTPTS[v0]; \
        [1:v]setpts=PTS-STARTPTS+{notify_start}/TB[v1]; \
        [v0][v1]overlay=enable=\'between(t, {notify_start}, {notify_start + get_duration(os.path.join(path, "popup.mp4"))})\' [out1]" \
        {render_flags} -r 24 -map 1:a -map [out1] -async 1 \
        {os.path.join(source_folder, "test.mp4")}')


  


  What this does is that popup.mov shows up at 30 seconds and plays for its entire duration. However, I have two issues :

  


  

  1. popup.mov's audio still plays at the beginning. I've tried itsoffset, setting the pts but both seem to not work or have errors.

  


  2. The only audio playing is popup.mov's audio. I would like both 2minutevideo and popup.mov to play audio. Yes, I'm aware it's because -map 1:a only maps the popup's audio to the final video, but I have no idea how to have both audio play. Would I have to mix it ?

  


  


  Thank you

  


• FFMPEG encoding 16bit video data results in 10bit

  12 mars 2023, par Jl arto

  I want to compress a depth map that has 16 bits of information per pixel. In general, such depth maps can be stored in different ways, e.g. p016le, gray16le, yuv420p16le, yuv444p16le, ... but for simplicity, let's assume the depth map is a yuv420p16le (where the y-channel contains the depth).

  


  For some reason when encoding with hevc_nvenc (I use an NVIDIA GTX 1660 Ti GPU), ffmpeg (the command line tool) changes the pixel format to a 10 or 12 bit variant (p010le, gray12le, yuv420p10le, yuv444p12le, ...), but I would like to keep the full 16 bits, since this affects the quality of the depth stored.

  


  For example :

  


  ffmpeg.exe -s:v 1920x1080 -r 30 -pix_fmt yuv420p16le -i depth_yuv420p16le.yuv -c:v hevc_nvenc -pix_fmt yuv444p16le output.mp4


  


  If I use ffprobe on the output.mp4, it tells me that the underlying pixel format is actually yuv444p10le. (Decoding and looking at the raw pixel data, I can confirm that the precision has decreased from 16 bits to 10 bits).

  


  I hope 16 bit compression is possible, since according to

  


  ffmpeg -h encoder=hevc_nvenc


  


  the supported pixel formats are :

  


  hevc_nvenc: yuv420p nv12 p010le yuv444p p016le yuv444p16le bgr0 rgb0 cuda d3d11


  


  But p016le results in a p010le output, and yuv444p16le in yuv444p10le.

  


  Does anyone know where the problem could lie ? Should I re-install ffmpeg (version 4.3.2-2021-02-27-essentials_build-www.gyan.dev) ? Is it because of Windows 10 having limited encoding/decoding capabilities ? Will buying the HEVC Video Extensions help solve this problem ?

  


  Additional info : using libx256 does not look like it will work for this purpose, since the supported pixel formats are :

  


  libx256 : yuv420p yuvj420p yuv422p yuvj422p yuv444p yuvj444p gbrp yuv420p10le yuv422p10le yuv444p10le gbrp10le yuv420p12le yuv422p12le yuv444p12le gbrp12le gray gray10le gray12le


  


  Any help would be greatly appreciated.