RTSP stream, effect of max-lateness + qos

[Guillermo Rodriguez Garcia]

Hello,

There is no GPU acceleration available in this system.

Best,

Guillermo

El viernes, 12 de mayo de 2023, cfd new <newcfd at yahoo.com> escribió:

> avdec uses CPU for decoding and makes your CPU very busy. Try to use vaapi
> or va decoder with GPU acceleration to reduce CPU load.
>
> On Friday, May 12, 2023, 08:45:28 a.m. EDT, Guillermo Rodriguez Garcia via
> gstreamer-devel <gstreamer-devel at lists.freedesktop.org> wrote:
>
>
> Hi all,
>
> I have an embedded device showing RTSP / H.264 video streams from IP
> cameras.
>
> The pipeline is more or less like this:
>
> gst-launch-1.0 rtspsrc XXX ! rtph264depay ! h264parse ! avdec_h264 !
> waylandsink
>
> In some cases the resolution of the video stream is too high for the
> device to decode comfortably (unfortunately this is not something I
> can control). In these cases, Gstreamer (waylandsink actually I guess)
> decides that the frames are arriving too late, and discards them. The
> result is that the video is frozen (or almost -- I see a frame being
> displayed every now and then).
>
> I thought that displaying late frames was better than displaying a frozen
> video so I tried to add max-lateness=-1 to the sink. However this does not
> seem to change anything. Next I tried to set qos=false instead, this didn't
> help either.
>
> However setting _both_ max-lateness=-1 and qos=false does work. WIth this
> I can see the video stream even if there is a very noticeable delay.
>
> I am trying to undestand how this works and I have some questions;
> hopefully someone can help.
>
> 1. Why setting max-lateness=-1 alone is not enough? If I understand
> correctly this should make the sink consider that no frames are late, so it
> should not be sending qos events. Why is it necessary to combine
> max-lateness=-1 with qos=false ?
>
> 2. What is the difference in practice between max-lateness=-1 + qos=false
> and sync=false? Both seem to achieve a similar effect, but I have read that
> "setting sync=false is almost never the right solution for timing problems".
>
> Thank you,
>
> Guillermo Rodriguez Garcia
> guille.rodriguez at gmail.com
>


-- 
Guillermo Rodriguez Garcia
guille.rodriguez at gmail.com
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