Recherche avancée

Sur d’autres sites (5381)

• ffplay won't with with more than 6 audio channels

  13 juin 2020, par Hiko Haieto

  I am trying to stream (raw) video and audio from a capture device as part of my home media setup (with my pc acting similarly to a receiver in a typical home theatre setup), but the biggest problem I haven't been able to get past is that I haven't been able to get ffplay to work with all 8 channels in 7.1 streams - two simply get dropped, despite it recognising 8 channel input or me specifying a 7.1 layout.

  



  I have been able to confirm that all 8 channels are present in the source by first using ffmpeg to save the output of a speaker test to a file and playing that back with both mplayer (which works) and ffplay (which doesn't). I might simply use mplayer if it weren't for the fact that piping output from ffmpeg adds too much latency for real-time use. I am using libSDL version 2.0.12 and ffplay 4.2.3, both of which are the latest at the time of writing and are ostensibly supposed to support 7.1 audio.

  



  Using output recorded from speaker-test -c 8, I am using the following to play it back in mplayer :

  



  mplayer -channels 8 -rawaudio channels=8 -format s16le -demuxer rawaudio speaker-test.pcm


  



  and the following to play it back in ffplay :

  



  ffplay -f s16le -ac 8 -af 'channelmap=channel_layout=7.1' speaker-test.pcm


  



  No matter what I try, ffplay is dropping the two side channels. Why might ffplay not be producing output for all 8 channels, and how might I fix it ?

  


• avformat/matroskaenc : Check for failure when writing SeekHead

  29 décembre 2019, par Andreas Rheinhardt

  avformat/matroskaenc : Check for failure when writing SeekHead
  mkv_write_seekhead() would up until now try to seek to the position where
  
  the SeekHead ought to be written, write the SeekHead and seek back. The
  
  first of these seeks was checked as was writing, yet the seek back was
  
  unchecked. Moreover the return value of mkv_write_seekhead() was unchecked
  
  (the ordinary return value was the position where the SeekHead was written).
  This commit changes this : Everything is checked. In the unseekable case
  
  (where the first seek may nevertheless work when it happens in the buffer)
  
  a failure at the first seek is not considered an error. In any case,
  
  failure to seek back is an error.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• How to use the FFmpeg blackdetect filter for the following image

  17 septembre 2021, par dinesh47

  I am using FFmpeg to find the blackdetect from a mp4 video file. but for some reasons file with very low light or poor background at night get detected as black frame For sample i have attached the frame which detected as black

  


  My ffmpeg filter setting is "blackdetect=d=121:pix_th=0.00"

  


  my file has a resolution of 1280*720 and frame rate of 30 which uses decoder format of 4:2:0 YUV


  


  There are 2 Questions

  


  1.Why the ffmpeg lib detects this as black frame ?

  


  2.How to over come this ?