Recherche avancée

Sur d’autres sites (6375)

• FFmpeg multibirate encoding live stream

  10 août 2017, par Pat-rice

  We are doing multi-bitrate encoding to serve adaptive streaming.
  We are using the following command :

  ffmpeg -fflags +genpts -vsync 2 -re -f live_flv -c:v h264_cuvid -i input.mp4 -c:a aac -vsync 2 -c:v h264_nvenc -s 854x480 -f flv rtmp://output_480p -c:a aac -vsync 2 -c:v h264_nvenc -s 284x160 -f flv rtmp://output_160p -c:a aac -vsync 2 -c:v h264_nvenc -s 1280x720 -f flv rtmp://output_720p -c:a aac -vsync 2 -c:v h264_nvenc -s 640x360 -f flv rtmp://output_360p

  We had multiple version of this command, now we are trying to use the GPU as much as possible (h264_cuvid to decode and h264_nvenc to encode).

  Our problem is that, sometimes, randomly, one or many output is audio only with no video frames (black screen). We had the same bug using CPU only.

  After investigation the input audio/video frames seems to be not synchronized. The weird thing is that we are always using the same input file (Sintel) and the bug is still happening. The input is sent via rtmp.
  The option vsync 2 seems to be a bit more reliable than the default one, but it’s still happening. What would be the best strategy to synchronize audio and video frames based on timestamps (or smth else) ?

  Also is it better to set a frame size or a bitrate to generate a desired quality ?

• ffmpeg - invalid duration

  22 septembre 2016, par OmidAntiLong

  For a project I’m working on I have a small bash script that loops over an input csv file of timecodes, and uses ffmpeg to create screenshots of a given film at each timecode. The csv file is in the format hh:mm:ss,id - it looks like this (extract)

  00:00:08,1
  
  00:00:49,2
  
  00:01:30,3
  
  00:02:38,4
  
  00:03:46,5
  
  00:04:08,6
  
  00:04:26,7
  
  00:04:37,8
  
  00:04:49,9
  
  00:05:29,10
  
  00:05:52,11
  
  00:06:00,12
  
  00:06:44,13
  
  00:07:49,14
  
  00:08:32,15
  
  00:09:28,16
  
  00:10:17,17
  
  00:10:44,18
  
  00:11:48,19
  
  00:12:07,20

  I’ve used it without issue in the past, but today I’ve come to update some of the films and I’m getting a weird issue where ffmpeg is complaining that my input timecode is invalid, despite being in the right format.

  The new input csv files are the same format as the old ones, but it seems like every so often ffmpeg drops the hours from the hh:mm:ss timestamp. If I comment out the ffmpeg line, everything prints to the terminal as expected (but obviously I get no screenshots).

  This is my loop code :

  while read code a
  
  do
  
    echo $code
  
    f="$(printf "%03d" $i)"
  
  
  
    ffmpeg -loglevel error -y -ss $code -i $FILM -vframes 1 -q:v 2 $OUTPUT/$f.jpg
  
  
  
    ((i++))
  
  done < $INPUT

  I’ve tried all sorts, including padding the csv with extra 0s - which works until the hours tick over to 01.

  

  Does anyone have any ideas ? I’m scratching my head.

  Cheers

• where can one find old patches/curated versions of ffmpeg for qsv (mpeg2_qsv) ?

  10 avril 2023, par CodeCalf

  for the past year or so the mpeg2_qsv encoder in ffmpeg/libmfx has been broken due to a idr interval problem (sends only one idr frame at the start of the video rather than sending idr frames at a certain interval) i have found a solution/workaround by adding the idr-interval option defined in h264_qsv.c to the mpeg2_qsv.c provided in ffmpeg it does work but the quality of the output is subpar even after applying heavy post processing filters and i have been working on this exact platform for the past 4 years so i know for a fact that it used to work way better hence i have been trying to revert the changes made to ffmpeg in the past 1-2 years unsuccessfully as i am not able to find old patches that i could use as reference.

  


  i understand that for this problem a lot of people suggest using ffmpeg 2.8 which apparently is the best for old qsv behaviour but due to mediasdk version mismatches i haven't been able to build it successfully on any new OS after ubuntu 18.04 but i cannot use ubuntu 18.04 or below because of a hardware issue on my platform which messes with the xserver introducing a lot of weird errors if anyone has any suggestions of how i can overcome this then please help as i am all ears

  


  i am new to this website so i apologize in advance if i have made a mistake in asking this question.

  


  thank you for your patience and guidance