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• create max quality Frame with FFMPEG from ProRes Clip

  5 août 2021, par Josef Zugarov

  I want to extract a frame from a ProRes Clip, recorded with a Blackmagic URSA Mini Pro 4.6K Gen 2 camera with ffmpeg.
I noticed the following : When I import the ProRes Clip into Davinci I can recover some highlights, which are out of the displayed range by lowering the gain paramater.
As you can see in the waveform the thrid peak has information in all channels.

  


  After I extracted the frame with ffmpeg, I couldn't recover the highlights anymore.
Waveform : Values are clipped till the fifth peak.

  


  I used the following command :
ffmpeg  -ss 00:00:01 -i 0volt.mov -vf zscale=t=input,zscale=c=input -frames:v 1  TIFFs\0volt.tiff -v verbose

  


  Here is the output of the ffmpeg command line : https://pastebin.com/a36ML3tL

  


  Do you have any hint, how the original quality and dynanmic range by extracting a TIFF-Frame with ffmpeg can be retained ?

  


  Thank you !

  


• FFmpeg Throwing Up Error After Concat Attempt [closed]

  8 mai 2021, par OrdinaryCarrot16

  I am trying to convert my DVDs using FFmpeg, while doing additional filtering and concatenation. The script I am making is very WIP, but it isn't working at the moment. It throws up the error : "No such filter : ''
Error initializing complex filters.
Invalid argument"

  


  Am I using the correct syntax ?

  


  :: Generate dummy file with blank video & audio streams (for spacing out portions when concating)
ffmpeg -y -f lavfi -i color=size=720x480:color=black:rate=30 -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=44100 -c:a aac -c:v libx264 -t 1 spacer_1_tmp.mkv
ffmpeg -y -f lavfi -i color=size=720x480:color=black:rate=30 -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=44100 -c:a aac -c:v libx264 -t 2 spacer_2_tmp.mkv

:: Extract intro
ffmpeg -y -avoid_negative_ts make_non_negative -ss 00:00:01 -to 00:00:24.900 -i "ADVENTURE TIME SEASON 1 DISC 1_t00.mkv" -c:v libx264 -crf 8 -preset veryfast -c:a aac -b:a 192k intro_tmp.mkv

:: Extract title card, episode, and credits
ffmpeg -y -avoid_negative_ts make_non_negative -ss 00:00:25.850 -to 00:00:32.500 -i "ADVENTURE TIME SEASON 1 DISC 1_t00.mkv" -c:v libx264 -crf 8 -preset veryfast -c:a aac -b:a 192k title_card_tmp.mkv
ffmpeg -avoid_negative_ts make_non_negative -ss 00:00:32.900 -to 00:11:16.950 -i "ADVENTURE TIME SEASON 1 DISC 1_t00.mkv" -c:v libx264 -crf 8 -preset veryfast -c:a aac -b:a 192k episode_tmp.mkv
ffmpeg -y -avoid_negative_ts make_non_negative -ss 00:11:17.950 -to 00:11:50.900 -i "ADVENTURE TIME SEASON 1 DISC 1_t00.mkv" -c:v libx264 -crf 8 -preset veryfast -c:a aac -b:a 192k credits_tmp.mkv

:: Merge all extracted components and encode into final video
ffmpeg -i spacer_1_tmp.mkv -i intro_tmp.mkv -i spacer_2_tmp.mkv -i title_card_tmp.mkv -i spacer_2_tmp.mkv -i episode_tmp.mkv -i spacer_2_tmp.mkv -i credits_tmp.mkv -i spacer_1_tmp.mkv -filter_complex "[0:0]setsar=1[v1];[0:1][a1];[1:0]setsar=1[v2];[1:1][a2];[2:0]setsar=1[v3];[2:1][a3];[3:0]setsar=1[v4];[3:1][a4];[4:0]setsar=1[v5];[4:1][a5];[5:0]setsar=1[v6];[5:1][a6];[6:0]setsar=1[v7];[6:1][a7];[7:0]setsar=1[v8];[7:1][a8];[8:0]setsar=1[v9];[8:1][a9];[v1][v2][v3][v4][v5][v6][v7][v8][v9][a1][a2][a3][a4][a5][a6][a7][a8][a9]concat=n=9:v=1:a=1[fv][fa]" -map "[fv]" -map "[fa]" -c:v libx264 -crf 20 -c:a aac -b:a 160k "Slumber Party Panic (S01E02).mp4"

pause


  


• avformat/wavenc : Fix leak and segfault on reallocation error

  22 février 2021, par Andreas Rheinhardt

  avformat/wavenc : Fix leak and segfault on reallocation error
  Up until now, the wav muxer used a reallocation of the form ptr =
  
  av_realloc(ptr, size) ; that leaks upon error. Furthermore, if a
  
  failed reallocation happened when writing the trailer, a segfault
  
  would occur due to avio_write(NULL, size) because the muxer only
  
  prints an error message upon allocation error, but does not return
  
  the error.
  Moreover setting the pointer to the buffer to NULL on error seems to
  
  be done on purpose in order to record that an error has occured so that
  
  outputting the peak values is no longer attempted. This behaviour has
  
  been retained by simply disabling whether peak data should be written
  
  if an error occurs.
  Finally, the reallocation is now done once per peak block and not once
  
  per peak block per channel ; it is also done with av_fast_realloc and not
  
  with a linear size increase.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/wavenc.c