[Libav-user] Very slow av_write_frame

[Yurii Monakov]

I'm sorry, buffer_size option does not recognize short sizes. So it should
be "?buffer_size=200000".
You can find all udp protocol options here:
https://ffmpeg.org/ffmpeg-protocols.html#udp

Yurii

пт, 21 апр. 2023 г. в 10:48, Yurii Monakov <monakov.y at gmail.com>:

> 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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