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• Revert "avcodec/nvenc : fix b-frame DTS behavior with fractional framerates"

  14 juin 2023, par Timo Rothenpieler

  Revert "avcodec/nvenc : fix b-frame DTS behavior with fractional framerates"
  This reverts commit 9a245bdf5d7860b8bc5e5c21a105a075925b719a.
  This commit basically broke all samples with fractional framerates,
  
  rather than fixing them.
  
  I at this point do not understand the original issue anymore, and I'm
  
  not sure how this slipped my initial testing.
  
  All my test samples must have happened to have a simple timebase.
  The actual dts values pretty much always are just a simple chain of
  
  1,2,3,4,5,... Or maybe slightly bigger steps. Each increase by one means
  
  an advance in time by one unit of the timebase.
  
  So a fractional framerate/timebase is already not an issue.
  So with this patch applied, the calculation might end up substracting
  
  huge values (1001 is a common one) from the dts, which would be an
  
  offset of that many frames, not of that many fractions of a second.
  
  This broke at least muxing into mp4, if the sample happened to have a
  
  fractional framerate.
  I do not thing the original issue this patch tried to fix existed in the
  
  first place, so it can be reverted without further consequences.
  

  • [DH] libavcodec/nvenc.c

• Ffmpeg Stop recording pipeline when one of sources fall [closed]

  5 mai 2023, par Андрей Боярский

  Can't find the exact way how to make ffmpeg automatically stop recording from RTSP-sources when one of one of them fall.

  


  I have made two ffmpeg pipelines :

  


  

  1. ffmpeg -thread_queue_size 4096 -rtsp_transport tcp -use_wallclock_as_timestamps 1 -i ... -rtsp_transport tcp -thread_queue_size 4096 -use_wallclock_as_timestamps 1 -i ... -map_metadata 0 -c copy -map 0:1 -map 1:0 -shortest presenter.mkv -map_metadata 1 -map 1 -c copy -shortest presentation.mkv

  


  2. ffmpeg -thread_queue_size 4096 -rtsp_transport tcp -use_wallclock_as_timestamps 1 -timeout 5 -xerror -i ... -rtsp_transport tcp -thread_queue_size 4096 -use_wallclock_as_timestamps 1 -timeout 5 -xerror -i ... -map_metadata 0 -c copy -map 0:1 -map 1:0 presenter.mkv -map_metadata 1 -map 1 -c copy presentation.mkv

  


  


  In the first pipeline when one of sources fall, streams in result file stop at the point of time where the source fall, but the pipeline keeps working until it stopped manually, so the other result file have bigger length.
In th second one when one of sources fall, pipeline stops with error, but it don't write duration correctly, so it seemed like file have endless duration.

  


• Need to delete first output file after copy and re-encoding are done

  23 mars 2023, par Nicolò Conte

  I have a Sony SLT camera that records 1920x1080 50i AVCHD videos and produces .MTS files which contain h264 video data.
The files are hard to work with in video editing softwares and the interlacing isn't optimal for web or phones at all.
I used to re-encode into h264 through Premiere but its deinterlace feature doesn't seem to work and it's an overall slow procedure.

  


  As an end result I am looking to get a deinterlaced, h264 file in the fastest and lossless way possible.
I'm currently using Axiom as an FFmpeg GUI tool, however that doesn't feature a copy function or multiple steps.

  


  I have therefore tried adding some line parameters into the script generated by Axiom to only copy the h264 data first and then added a second step to re-encode with deinterlacing, this is the script :

  


  ffmpeg -y -hwaccel auto -i "input_filename.MTS" -c:v copy 
-c:a aac -strict experimental -b:a 128k "output_filename.mp4"

&&

ffmpeg -y -hwaccel auto -i "ouput_filename.mp4" -c:v libx264 
-preset medium -b:v 25000K -pix_fmt yuv420p -filter:v bwdif=mode=send_field:parity=auto:deint=all 
-map 0:v:0? -c:a aac -q:a 0.80037 -map 0:a? -sn -map_chapters 0 -map_metadata 0 -f mp4 -threads 0 
"second_output_filename.mp4" && del /f/q "%i"


  


  The script works correctly except that I can't figure out how to delete the first output, which is still interlaced h264 that I don't need, and a few more things.

  


  


  • Given that I have to do this for each and every video file from my camera I would ideally like to only change the first input file path+name and the last output file+name. I have no clue how to do this or how I could do so in batch. Ideally I would like for this to happen to all files within a folder.

    


  


  • del /f/q "%i" only searches for filename "%i" in the output directory, which obviously doesn't exist. As far as I understand this should be the name for the first output file, it would then work.

    


  


  • The videos have a 25Mb/s maximum bitrate, if I set Axiom to lossless quality it doubles that and the output files become huge. Using -b:v 25000K returns a 40% bigger file, which is not ideal.

    


  


  • I assume that I could copy the audio on both steps too ? Leaving that untouched would be a bonus.

    


  


  


  I tried to look for a solution multiple times but the search terms are too generic or I'm too much of a noob to find a working answer.
Thank you in advance.