RTSP latency issues, effect of sync=false

[Guillermo Rodriguez Garcia]

Hi all,

I am using GStreamer to fetch live video from IP cameras (RTSP /
H.264). My application does not require audio.

In some cases I am seeing stuttering video with many dropped frames,
and I see the typical "There may be a timestamping problem, or this
computer is too slow" messages on GStreamer's debug output.

Nonetheless I don't think this is a performance issue in the receiver:
Sometimes this happens for a low-bandwidth video stream (640x480, 15
fps, < 1 Mbps), and the problems will go away if I actually _increase_
the image resolution, frame rate, or bit rate in the camera itself.

I have checked the following:
- Adding queue elements between other elements in the pipeline doesn't
seem to help
- If I increase the latency parameter in the rtspsrc element (by
default I am setting this to 200ms), this fixes the problem (but also
introduces undesirable delays)
- If I add sync=false to the sink, this also fixes the problem

The last option seems to always fix the problem without introducing
any adverse side-effects (that I am aware of). My question is: Is
there any reason not to use this? Anything I should bear in mind? Note
that all streams are live, at any given time I am only using one
source and one sink (not mixing anything), and I am not using audio at
all.

Thank you,

Guillermo Rodriguez Garcia
guille.rodriguez at gmail.com