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• How to use ffmpeg to stream a playlist of clips that are in very different formats ? [closed]

  21 septembre 2024, par gulagkulak

  I'm trying to use ffmpeg to stream a playlist of video files that are all in very different formats, sizes, and aspect ratios.

  


  The problem is that often when the video changes I get a spinning wheel of death on the target streaming sites and some kinda error in the ffmpeg output.

  


  Sometimes it's [flv @ 0x7f5c10686200] Failed to update header with correct duration.

  


  Or [flv @ 0x7f5c10686200] Failed to update header with correct filesize.

  


  Or a whole bunch of [aost#0:1/aac @ 0x8947680] Non-monotonic DTS; previous: 82536459, current: 78988751; changing to 82536460. This may result in incorrect timestamps in the output file.

  


  Or it starts dropping every single frame. I think it happens when it changes from a progressive to deinterlaced file or vice-versa.

  


  How do I make ffmpeg more resilient so it can handle every kind of file thrown at it and output a continuous stream at 1920x1080 and 30fps h264 to a streaming server ?

  


  This is the command I'm using :

  


  ffmpeg -stream_loop -1 -re -f concat -i playlist.txt -threads 4 -c:v libx264 -preset ultrafast \
-b:v 2000k -maxrate 2000k -g 30 -c:a aac -b:a 128k -strict -2 -fflags +genpts+discardcorrupt \
-async 1 -map 0 -r 30 -s 1920x1080 -bufsize 6000k -flags +cgop -fflags +igndts \
-f tee -rtsp_transport tcp -max_delay 1000 \
"[f=flv:onfail=ignore]rtmp://xxxxxxxxxxxxxxx.com/live/xxxxxxxxxxxxxxx|[f=flv:onfail=ignore]rtmp://xxxxxxxxxxxxxxx.com/live/xxxxxxxxxxxxxxx"


  


  And it's not working. ffmpeg just fails in a variety of ways. I've spent two days trying to figure this out.

  


  Even used handbrake to try and pre-encode the video files to the same exact format, but even then ffmpeg fails in similar ways, just less often.

  


  After re-encoding with handbrake I tried to concat the videos together with ffmpeg and ended up with a large video where the sound breaks for some parts of it and it stops being seekable in VLC after a certain timecode.

  


  I think I'm missing some important ffmpeg flag or option.

  


• dds : Add support for alpha-only files

  1er avril 2016, par Vittorio Giovara

  dds : Add support for alpha-only files
  Due to how pixel format conversion is done, they behave the same way
  
  as gray files.
  Signed-off-by : Vittorio Giovara <vittorio.giovara@gmail.com>
  

  • [DBH] libavcodec/dds.c

• Resizing AVIF images with transparency with FFmpeg [closed]

  4 octobre 2024, par Calebmer

  I'm trying to resize an image with transparency with FFmpeg, however the output looks to only be a resized version of the alpha layer.

  


  When I try to do a noop transform of the AVIF image with an alpha layer :

  


  ffmpeg -i input.avif output.avif


  


  output.avif appears to be the alpha layer with black representing alpha 0 and white representing alpha 1.

  


  ffprobe input.avif gives me :

  


  ffprobe version 7.0.2 Copyright (c) 2007-2024 the FFmpeg developers
  built with Apple clang version 15.0.0 (clang-1500.3.9.4)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/7.0.2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
  libavutil      59.  8.100 / 59.  8.100
  libavcodec     61.  3.100 / 61.  3.100
  libavformat    61.  1.100 / 61.  1.100
  libavdevice    61.  1.100 / 61.  1.100
  libavfilter    10.  1.100 / 10.  1.100
  libswscale      8.  1.100 /  8.  1.100
  libswresample   5.  1.100 /  5.  1.100
  libpostproc    58.  1.100 / 58.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.avif':
  Metadata:
    major_brand     : avif
    minor_version   : 0
    compatible_brands: avifmif1miaf
  Duration: N/A, start: 0.000000, bitrate: N/A
  Stream #0:0[0x1]: Video: av1 (libdav1d) (Main) (av01 / 0x31307661), gray(pc), 336x252 [SAR 1:1 DAR 4:3], 1 fps, 1 tbr, 1 tbn (default)
  Stream #0:1[0x2]: Video: av1 (libdav1d) (High) (av01 / 0x31307661), yuv444p(pc, smpte170m/bt709/iec61966-2-1), 336x252 [SAR 1:1 DAR 4:3], 1 fps, 1 tbr, 1 tbn


  


  Seeing there are two streams (the first stream being gray(pc), probably the alpha layer) I next tried :

  


  ffmpeg -i input.avif -map 0:v:1 output.avif


  


  To see the second stream and it gave me the image without any alpha channel. Transparent pixels were black.

  


  Ultimately I want to resize the AVIF file with ffmpeg -i input.avif -vf "scale=iw/2:-1" output.avif but that appears to only resize the greyscale alpha channel. Furthermore, this will be part of a script that operates on some AVIF files without an alpha channel and some AVIF files with an alpha channel and I don't know which files have an alpha channel ahead of time. ffmpeg -i input.avif -vf "scale=iw/2:-1" output.avif works for files without an alpha channel.