[FFmpeg-user] Let ffmpeg pick correct fps from stdin

Moritz Barsnick barsnick at gmx.net
Thu Jan 14 12:54:54 CET 2016

On Thu, Jan 14, 2016 at 11:57:42 +0100, Jean-Marie Baran wrote:
> fmpeg -y -thread_queue_size 1024 -f s16le -ar 44100 -i 
> tcp://localhost:5624?listen=1 -re -f mjpeg -thread_queue_size 1024 -i - 
> -c:v libx264 -preset fast -crf 28 -vsync 0 -strict -2 -acodec aac 
> -threads 0 -ar 44100 file.mp4
> ...

Please show us the full, uncut console output. It contains valuable
information (especially about the detection of the input and the
configuration of the output formats/codecs).

Furthermore, you are using two inputs (tcp://localhost:5624?listen=1
and stdin). Can you reproduce this problem with just your stdin? If so,
please show us that command line and the complete console output.

> So ffmpeg seems to be able to retrieve the fps (13, then 12, then 11, 
> ...), but it doesn't use it for the recorded video. My best bet was to 
> use "-re" but it did not change anything.

That "fps=" is the number of frames per seconds ffmpeg is sending to
its output. In certain situations, and with "-re", that may very well
correspond to the input frame rate.

I think the first task would be to determine whether your stdin
actually can deliver your desired 25 fps, but show us your console
outputs first please.


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