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• 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'.

  


• an error happened : spawn ENOENT, node.js & FFmpeg

  20 juin 2014, par user2757842

  I am having a nightmare of a time trying figure this out. I asked a question about this yesterday but only got so far, long story short, I cannot for the life of me figure this out.

  All i want to do, is transcode a .avi file to a .flv file using FFmpeg in a node.js app, this works just using the command line for FFmpeg but not in the app, here’s the code :

  var ffmpeg = require('fluent-ffmpeg');
  
  
  
  //make sure you set the correct path to your video file
  
  var proc = new ffmpeg({ source: 'C:/Users/Jay/Documents/movie/drop.avi', nolog: true });
  
  
  
  //Set the path to where FFmpeg is installed
  
  proc.setFfmpegPath("C:\\Users\\Jay\\Documents\\FFMPEG\\bin");
  
  
  
  proc
  
  //set the size
  
  //.withSize('50%') <-- error appears after this line
  
  
  
  // set fps
  
  //.withFps(24)
  
  
  
  // set output format to force
  
  //.toFormat('flv')
  
  
  
  // setup event handlers
  
  .on('end', function() {
  
      console.log('file has been converted successfully');
  
  })
  
  .on('error', function(err) {
  
      console.log('an error happened: ' + err.message);
  
  })
  
  // save to file <-- the new file I want -->
  
  .saveToFile('C:/Users/Jay/Documents/movie/drop.flv');

  The error appears on the line specified above, it’s not an error with red writing, but it simply says :

  an error happened: spawn ENOENT

  Has anyone come across this ?

• FFMPEG streaming raw H264

  29 avril 2020, par lbasek

  Im currently working on streaming a mp4 file encoded with h264 over TCP and decoding at the mobile side (Android).I successfully manage up connection and streaming h264 raw data but that image quality is too bad (half screen is green or purple and everything is pixelized).I started streaming with :

  



  ffmpeg -re \                                                       
-i test.mp4 \
-vcodec libx264 \
-vf scale=1920:1080 \
-vprofile high \
-preset ultrafast \
-b:v 1M -maxrate 2M -bufsize 2M -pass 1 \
-strict experimental \
-pix_fmt yuv420p \
-tune zerolatency \
-movflags use_metadata_flag \
-movflags empty_moov+default_base_moof+faststart \
-f h264 tcp://10.230.253.241:9090


  



  Result :
Image

  



  Am I on right road and its that possible with raw h264 ? Any advice would welcome ! Thanks