[Libav-user] Very slow av_write_frame

[Yurii Monakov]

By default ffmpeg uses 32k for the send buffer size, so maybe this is a
blocking I/O issue.
You can increase buffer size by adding "?buffer_size=200k" option to the
destination url.
Send buffer size is also limited with system-wide setting "
net.core.wmem_max".

Yurii

пт, 21 апр. 2023 г. в 08:30, wolverin via Libav-user <libav-user at ffmpeg.org
>:

>
>
> Пятница, 21 апреля 2023, 9:59 +05:00 от Yurii Monakov <monakov.y at gmail.com
> >:
>
> Hello,
>
> 100 Mbit/s is a measured speed or maximum link speed? If it is theoretical
> maximum, than you can measure real UDP speed with iperf3.
>
> Yurii
>
>
> Thank you for paying attention to my problem.
>
> 100 Mbit/s is a maximum link speed.
>
> I used v4l2rtspserver to send a video stream via udp and it is capable of
> sending traffic at speeds up to 80Mbit/s, so this is not a hardware or
> measurement problem.
>
> For av_write_frame runtime measurements, I calculate the difference
> between the time before and after and for 200Kb it's a terrible 300-350ms.
> If required, I will provide my source code that does something similar
> ffmpeg -i file.mjpeg -f mjpeg udp://host:port
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