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• Force ffmpeg to quit when input resolution changes

  22 octobre 2022, par rednine

  I'm using ffmpeg to restream a live feed. Unfortunately occasionally the input resolution changes but ffmpeg continues running. The nginx rtmp server I'm using doesn't cope well with this, and continues the stream with audio, but the video is mostly black or green with some artifacts.

  


  Ideally what I want to happen is for ffmpeg to stop on an input resolution change, as I have a script that detects ffmpeg stopping and will restart it again.

  


  I'm using -c:v copy in my ffmpeg command as unfortunately my machine is not powerful enough to re-encode the live video on the fly to a constant resolution (not without a significant quality reduction at least)

  


  ffmpeg -i "http://mpegts-live-stream" -c:v copy -c:a aac -ac 2 -f flv "rtmp://nginxserver/live/streamname"

  


• avformat/daudenc : force 2000 sample packet size with a bsf

  3 mars 2024, par Marton Balint

  avformat/daudenc : force 2000 sample packet size with a bsf
  The samples I found all have 2000 sample packets, and by forcing the packet
  
  size with a bsf we could automagically make muxing work for packets containing
  
  more than 3640 samples.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] configure
  • [DH] doc/muxers.texi
  • [DH] libavformat/daudenc.c
  • [DH] tests/ref/fate/dcinema-encode

• Ffmpeg - How to force MJPEG output of whole frames ?

  27 août 2021, par Maoration

  I'm working with ffmpeg to process an incoming MPEGTS stream from remote cameras, and deliver it to multiple clients using my app.

  



  Technically, I'm using ffmpeg to convert the incoming stream to an MJPEG output, and piping the data chunks (from the ffmpeg process stdout) to a writeable stream on the client http response.

  



  However, I'm facing a problem- not all data chunks represent a full 'whole' frame. thus, displaying them in a row in the browser, results in a flickering video, with half-complete frames, on a random basis.
I know this because when printing each chunk length, results most of the time in a big value (X), but every now and then I get 2 consecutive chunks with length (2/5X) followed by (3/5X) for example.

  



  So the question - is there a way to force the ffmpeg process to output only whole frames ? if not, is there a way for me to check each data chunk 'manually' and look for headers/metadata/flags to indicate frame start/end ?

  



  ---

  



  my ffmpeg command for outputting MJPEG is :

  



  ffmpeg -i - -c:v mjpeg -f mjpeg -


  



  explained :

  



  "-i -" : (input) is the stdin of the process (and not a static file)

  



  "-c:v mjpeg" : using the mjpeg codec

  



  "-f mjpeg" : output will be in the mjpeg format

  



  "-" : output not specified (file or url) - will be the process stdout

  



  ---

  



  Edit :
here are some console.log prints to visualize the problem :

  



  %%% FFMPEG Info %%%
frame=  832 fps= 39 q=24.8 q=29.0 size=   49399kB time=00:00:27.76 bitrate=14577.1kbits/s speed=1.29x    
data.length:  60376
data.length:  60411
data.length:  60465
data.length:  32768
data.length:  27688
data.length:  32768
data.length:  27689
data.length:  60495
data.length:  60510
data.length:  60457
data.length:  59811
data.length:  59953
data.length:  59889
data.length:  59856
data.length:  59936
data.length:  60049
data.length:  60091
data.length:  60012
%%% FFMPEG Info %%%
frame=  848 fps= 38 q=24.8 q=29.0 size=   50340kB time=00:00:28.29 bitrate=14574.4kbits/s speed=1.28x    
data.length:  60025
data.length:  60064
data.length:  60122
data.length:  60202
data.length:  60113
data.length:  60211
data.length:  60201
data.length:  60195
data.length:  60116
data.length:  60167
data.length:  60273
data.length:  60222
data.length:  60223
data.length:  60267
data.length:  60329
%%% FFMPEG Info %%%
frame=  863 fps= 38 q=24.8 q=29.0 size=   51221kB time=00:00:28.79 bitrate=14571.9kbits/s speed=1.27x  


  



  As you can see, a whole frame is about 60k (my indication is a clean video stream i'm viewing on the browser), but every now and then the output consists of 2 consecutive chunks that add up to 60k. when delivered to the browser, these are 'half frames'.