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• fate : adjust AAC encoder TNS test fuzziness

  29 août 2015, par Rostislav Pehlivanov

  fate : adjust AAC encoder TNS test fuzziness
  Tests fails on some ARM builds but it’s close enough so it’s okay.
  
  NEON, half-precision floats, rounding errors, who knows.
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] tests/fate/aac.mak

• flv live stream audio delay with ffmpeg refresh rate option

  15 janvier 2018, par albert200000

  I have problem with live http flv stream. I’m using the following command and it works great except for the audio. Audio has delay that increasing over time. I can fix the this by removing refresh rate option on the output (-r 30) but then stream latency goes higher for about half second.

  ffmpeg -f v4l2 -threads 0 -video_size 672X420 -i /dev/video1 -f alsa -thread_queue_size 512 -i hw:1,0 -c:a aac -ar 44100 -b:a 128k -c:v libx264 -s 672x420 -r 30 -g 60 -preset superfast -tune zerolatency -strict -2 -f flv rtmp://localhost/live/primary

  Can someone explain why this happening and what possible fixes are ?
  On the client I’m using Chrome with flv.js library.
  On the server Node-Media-Server.

• 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'.