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• ffmpeg showspectrumpic fscale=log not rendering Right audio channel

  8 janvier 2021, par hjeannin

  I am running these two command and getting surprising result on the second one.

  


  The first command produce (fscale=lin) :

  


  ffmpeg -i stereo-test.mp3 -lavfi showspectrumpic=s=600x600:mode=separate:fscale=lin:scale=log spect_lin.bmp


  


  spect_lin.bmp

  


  but the second command produce (fscale=log) :

  


  ffmpeg -i stereo-test.mp3 -lavfi showspectrumpic=s=600x600:mode=separate:fscale=log:scale=log spect_log.bmp


  


  spect_log.bmp

  


  Sadly on the second image, the right channel is missing and I cannot figure out why.
Any idea or suggestion would be awesome :)

  


  Thanks !

  


  PS : You can find my test file here : stereo-test.mp3

  


  I am using : ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers

  


  EDIT : does not work using ffmpeg version 4.3.1-4ubuntu1 Copyright (c) 2000-2020 the FFmpeg developers too.

  


• OBS and OBS Portable Recording Into Same File Simultaneously

  26 juin 2020, par aerodavo

  Corrupted video file, FFprobe output text file, and FFmpeg output text files are all available to download here :
https://drive.google.com/drive/folders/1R0Y5plgkhTWWFNNKgSNJ5yitpKQbIKgg?usp=sharing

  


  I'm hoping there is a way to extract good video and audio from this video file, this was for a very important job that is impossible to do again. The video linked is a 1 minute recreation of the exact same problem... the actual video file is confidential (for a legal court case) and is much longer/larger. I used the exact same settings, the only difference was the window OBS was capturing (I used a YouTube video as opposed to the videoconference software window used for the deposition).

  


  Here's what happened :

  


  In OBS and OBS Portable, I had the save location set to the same exact folder (this was not how I intended it to be, but I made a last minute change to accommodate what I suspected was a faulty hard drive). I also had a hotkey to start recording on both apps simultaneously. I left the auto-naming scheme in place for both instances of OBS since they were supposed to be saving to two totally different external hard drives. I have since changed the auto-naming so it won't happen again, but this perfect storm resulted in both recordings being written into a single file (see link above), instead of two files as intended. It is unplayabe in VLC.

  


  I ran an FFprobe (available via link above), and found that there are 8 streams in the file. Each file should have had 4 streams (1 video and 3 audio streams per my setup in OBS), so at first glance it looks like all the data is there in some form/arrangement.

  


  I tried to map the 0:0 stream to a new file and tried the same thing with the 0:4 stream (these are the video streams), but did not have any luck extracting good video. Here are the two things I ran (again see link above for text files with full FFmpeg ouput of each) :

  


  ffmpeg -i C :\Users\David\Videos\2020-06-23_17-39-32_corrupted.mkv -map 0:0 -c copy C :\Users\David\Videos\2020-06-23_17-39-32_corrupted_map0-0.mkv

  


  ffmpeg -i C :\Users\David\Videos\2020-06-23_17-39-32_corrupted.mkv -map 0:4 -c copy C :\Users\David\Videos\2020-06-23_17-39-32_corrupted_map0-4.mkv

  


  It seems the audio is intact, as I was able to map one of the audio streams into a wav file... although there seemed to be extra/repeated audio tacked onto where the video/audio should have ended...

  


  It looks to me like both video streams got written into stream 0:0, while stream 0:4 looks empty (because this map results in a very small file). However the thing that's weird (and maybe promising) is that when I play the corrupted file in VLC, it mostly looks like smeared digital colors, but if I click around to different times in the video, it sometimes shows good video, even though it won't show any good video if you just play it from the beginning.

  


  My life would saved if there is a way to extract good video/audio from this corrupted file. Any help would be greatly appreciated, thanks in advance !

  


• avfilter/pthread : use slice threading from avutil

  12 juillet 2017, par Muhammad Faiz

  avfilter/pthread : use slice threading from avutil
  Benchmark (with 2 cpus) :
  
  ./ffmpeg -f rawvideo -s 1280x720 -t 1000 -i /dev/zero \
  
      -filter_threads $threads -vf transpose=clock -f null null
  
  threads=2 :
  
    old : 31.129s 31.446s 31.574s
  
    new : 29.602s 29.636s 29.656s
  
  threads=3 (nb_threads = nb_cpus + 1 is bad choice at this situation) :
  
    old : 40.132s 40.279s 40.279s
  
    new : 39.308s 39.570s 39.693s
  
  threads=4 :
  
    old : 31.306s 31.366s 31.654s
  
    new : 30.231s 30.360s 30.451s
  Signed-off-by : Muhammad Faiz <mfcc64@gmail.com>
  

  • [DH] libavfilter/pthread.c