H264 and SEI messages

[Sebastian Dröge]

On Fr, 2014-01-24 at 11:00 -0500, Chuck Crisler wrote:
> I am using GStreamer 0.10.30 (sigh). I have an input source that is an RTSP
> server that is using SEI messages. The stream is multiplexed into MP2T and
> then converted back to RTP. The problem is that the SPS/PPS/SEI messages on
> the output side have timestamps equal to the previous frame while on the
> input side the timestamps equal the next frame. When the output RTP is sent
> to VLC on Windows, it doesn't display well. It pauses, then plays several
> seconds very quickly, then pauses.
> 
> 2 Questions.
> 
> 1. Is it likely that the SEI timestamp change is responsible for this issue?
> 2. Should I try to shift the SEI timestamps to the next frame in rtph264pay?
> 
> I don't have much experience with SEI messages. The RTP that I have worked
> with in the past didn't use them.

You might want to try if this is still like that with 1.0. In theory
(after h264parse if it outputs with alignment=AU) you will get
everything from the end of the previous frame until the end of the
current frame in a single buffer and thus with the timestamp.

That means that any SPS/PPS/SEI that comes in front of a frame will be
bundled together with that frame in the same buffer with the same
timestamp.

Everything else would seem like a bug. Not sure how it works in
alignment=NAL mode.

-- 
Sebastian Dröge, Centricular Ltd - http://www.centricular.com
Expertise, Straight from the Source
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