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• FFMpeg - how to encode a F4M manifest file to mp4

  20 novembre 2015, par Roee

  I’m working on a project, where we want to encode flash videos to mp4 (for example, we want to encode a f4v file), and live-stream them (which means we can’t just download all the f4f files, then encode them to a single mp4 and just then stream it. The encoding and streaming has to be done while downloading the files).

  If the format of the flash video is flv for example, FFMpeg can do what I’ve described without any problem. I just give the address of the flv file to FFMpeg, and it encodes and streams it as mp4.

  But, if the format of the flash video is something more complicated as f4v (which gets downloaded as many f4f files), I don’t have a single url to give to FFMpeg as input - I have many addresses of f4f files. I don’t even know how many f4f files the video has before playing it - it looks like the flash player just fetches the next f4f file when needed.

  I read online that there is a manifest file (its extension is f4m), that "describes" to the flash player which f4f files it should download and play, and what’s their playing-order and everything.

  My question is - if I have the url of this f4m file, what should I do in order to encode all its f4f files to mp4 ?
  I’ve tried to give to FFMpeg just the f4m file as input, but it doesn’t know what to do with it...

  I’ll really appreciate any response that might help, as I’ve been working on this issue for few days now and I still haven’t found any answer...

  Thanks,
  Roee.

• Systematic artefacts from 10bit source

  8 janvier 2015, par user3729198

  When encoding from a 10 bit source file, compression / color artifacts appear. From what I can see, the problem lies in the "dc precision" command "-dc". I have tried different combinations and these are my results.

  On HD encodings ”-dc8” will give you nice clean solid colors without artifacts. But gradients and shading will suffer and be rougher.

  On HD encodings ”-dc11” will give you bad compression and color artifacts that look very systematic. But the Gradients look nice and smooth.

  On SD encodings ”-dc8” will give you nice clean solid colors without artifacts. But gradients and shading will suffer and be rougher.

  On SD encodings ”-dc9” will give you bad compression and color artifacts that look very systematic. But the Gradients look nice and smooth.

  Why is this ? And can it be fixed ? From other encoding software’s if I mimic the settings, all the encodings looks nice in all cases. So it seems that there is a bug in ffmpeg.

  Here is an example of the ffmpeg command I use :

  -i INPUT -vcodec mpeg2video -aspect {$aspectRatio} -r 25 -pix_fmt yuv422p -timecode_frame_start 0 -minrate 150000k -maxrate 150000k -b 150000k -intra -flags +cgop -flags2 +ivlc+non_linear_q -dc 11 -sc_threshold 1000000000 -qscale 1 -qmin 1 -qmax 12 -bufsize 47185920 -rc_init_occupancy 47185920 -rc_buf_aggressivity 0.25 -s {$resolution} -vframes {$frameDuration} -an OUTPUT

  If you want to try it yourself, make sure your source is 10bit, like Uncompressed 10 bit YUV.

• ffmpeg make images to a video stream

  22 septembre 2023, par ruyi1111

  when I try to python this program, it would like to show error :[h264 @ 000001a2da51a280] cbp too large (479) at 61 25
[h264 @ 000001a2da51a280] error while decoding MB 61 25.
I have no idea to solve it.Can you give me some advices ?
My program :
enter image description here

  


  And error :
enter image description here

  


  when I try to run this introdutc
python3 face_recognition_sample.py | ffmpeg -f rawvideo -pixel_format bgr24 -s 1920x1080 -framerate 30 -i - foo4.avi

  


  it will output :
enter image description here

  


  So can anyone give some solutions ? Thanks !!!

  


  I want to make rtsp images to a stream, so I choose ffmpeg. But I met some questions.
I expect some one can give me some advices,thanks !!!!