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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'.

  


• 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

  


• Convert WAV to FLAC or ALAC whilst preserving/converting id3 tags [closed]

  28 mars 2023, par Jai_1008

  Basically I want to render my mastered audio out of Wavelab, (the industry standard for mastering music) and then be able to have my track added to the macOS Music app with all metadata already included.

  


  It's more complicated than this, but basically Wavelab only gives serious metadata options to its WAV output. If I render out as FLAC, which, as a format, has better metadata implementation than WAV files, the metadata options I have avialable in Wavelab are not as good/extensive.

  


  So to get the metadata I want, I have to render as WAV. But then I can't put that in Apple Music app whilst keeping it's id3 tags. All the fields like Artist etc are blank in the Music app.

  


  The Music app DOES recognise the metadata from an ALAC file. So I have to convert a WAV to ALAC (or FLAC as converting FLAC to ALAC is easy) whilst somehow preserving its metadata. And for the life of me, I cannot find an answer to this from searching and reading everything.

  


  Any help ? I was looking into ffmpeg as an option, but no one speaks to this specific situation of mine. Converting WAV to FLAC or ALAC and preserving the WAVs metadata (id3 tags).

  


  I've tried using -map_metadata 0 when converting a WAV to FLAC in ffmpeg, but ffmpeg says it's ignoring ID3 tags because it found more suitable metadata. But the resulting FLAC only has Artist and copyright fields included in its metadata.