[FFmpeg-user] RTSP to Twitch

[Moritz Barsnick]

Hi Sébastien,

On Wed, Mar 10, 2021 at 12:55:25 +0100, Sébastien Bonaimé wrote:

> included x264 codec are : libx264 libx264rgb h264_omx h264_v4l2m2m h264_vaapi

>         ffmpeg  -probesize  10M  -rtsp_transport tcp -thread_queue_size 1000k \
>                   -i $url \
>                 -vsync 0 -enc_time_base -1 \
>                  -bufsize 1024k -preset "$QUAL" \
>                 -b:v $CBR  -minrate $CBR -maxrate $CBR   -keyint_min 24 -g 24 \
>                 -crf 10  -c:v libx264    \
>                 -f flv $twitch_url
>
> With camera in CBR mode, I can't reach 25 FPS but only 14. And the
> stream to twitch does not last more than ew seconds. What can I do to
> improve the command ?

- Do you really need to reencode for twitch? Does it need CBR?
  Otherwise, you could just use the "copy" codec.

- AFAIU, you cannot combine "-b:v" and "-crf". I believe (fro mlooking
  at your logs) that the latter is being ignored.

- CRF 10 is really really low. What are you trying to achieve? Is the
  default of CRF 27 not good enough? CRF 10 is bound to take a lot of
  additional compute power (if not ignored).

- You listed other available encoders. Have you tried any of them? (I
  have no experience with HW accel on RaspPi, others may pitch in.)

> FFmpeg version is
> ffmpeg version 4.1.6-1~deb10u1+rpt1 Copyright (c) 2000-2020 the FFmpeg developers

You should try to get hold of a newer version of ffmpeg. You may have
to compile yourself though. A newer version probably won't help with
the speed of libx264, but the support for the other HWAccels may have
improved.

Cheers,
Moritz