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• lavc/decode : track whether the caller started draining with a separate flag

  20 juin 2023, par Anton Khirnov

  lavc/decode : track whether the caller started draining with a separate flag
  Decoding pipeline has multiple stages, some of which may have their own
  
  delay (e.g. bitstream filters). The code currently uses
  
  AVCodecInternal.draining to track all of them, but they do not have to
  
  all be in sync.
  

  • [DH] libavcodec/decode.c

• How to convert VP8 track with different frame resolution to h264

  13 septembre 2016, par Nikita

  I have a .webm file with VP8 track, recorded from WebRTC stream by external service (TokBox Archiving). The stream is adaptive, so each frame in track could have different resolution. Most players (in webkit browsers) use video resolution from track description (which is always 640x480) and scale frames to this resolution. Firefox and VLC player uses real frame resolution, changing video resolution respectively.

  I want to achieve 2 goals :

  1. play this video in Internet Explorer 9+ without additional plugin installation.
  2. change frames resolution to one fixed resolution, so the video will look identically in different browsers.

  So, my plan is :

  • extract frames from source webm file to images with real frame resolution (e.g. PNG or BMP) (how could I do that ?)
  • find max width and max height of images
  • add black padding to images, so smaller frames will be in the center of a new frame (of size MAX_WIDHTxMAX_HEIGHT)
  • combine images to h264 track using ffmpeg

  Is all correct ? How can I achieve this ? Can this algorithm be optimized some way ?

  I tried ffmpeg to extract images, but it does not parse real frame resolution, using resolution from track header.
  I think some libwebm functions can help me (to parse frame headers and extract images). Maybe someone has some code snippets to do this ?

  Example .webm (download source, do not play google-converted version) : https://drive.google.com/file/d/0BwFZRvYNn9CKcndhMzlVa0psX00/view?usp=sharing

  Official description of adaptive stream from TokBox support : https://support.tokbox.com/hc/en-us/community/posts/206241666-Archived-video-resolution-is-supposed-to-be-720x1280-but-reports-as-640x480

• How can I get metadata of playing track when I stream via ffmpeg ?

  10 juin 2022, par Viktor Kushnir

  I have one video.mp4 in loop and collection of mp3 that also plays in loop.

  


  start.sh

  


  #! /bin/bash

VBR="4500k"
FPS="30"
QUAL="superfast"

YOUTUBE_URL="rtmp://a.rtmp.youtube.com/live2/XXXX-XXXX-XXXX-XXXX-XXXX"
VIDEO_SOURCE="video.mp4"
AUDIO_ENCODER="aac"

ffmpeg \
-stream_loop -1 \
-re \
-i "$VIDEO_SOURCE" \
-thread_queue_size 512 \
-stream_loop -1 \
-re \
-f concat -i playlist.txt \
-vf drawtext="fontfile=OpenSans.ttf:text='Track Title':fontsize=26:fontcolor=white:borderw=1:bordercolor=black:x=40:y=1020" \
-map 0:v:0 -map 1:a:0 \
-map_metadata:g 1:g \
-c:v libx264 -preset $QUAL -r $FPS -g $(($FPS *2)) -b:v $VBR -bufsize 3000k -maxrate $VBR \
-c:a $AUDIO_ENCODER -ar 44100 -b:a 128k -pix_fmt yuv420p \
-f flv \
-flvflags no_duration_filesize \
$YOUTUBE_URL 


  


  I want to show in drawtext playing track metadata like title, artist...
ffmpeg show me only frame, fps, bitrate..

  


  frame=29717 fps= 25 q=19.0 size=  420802kB time=00:19:47.80 bitrate=2902.2kbits/s speed=0.999x


  


  Is it posible ?
Thank you