Different behaviour in using RTSP + RTP in streaming

[Tran Tu]

Hi all,

I wrote an application to stream dual streams through RTSP and RTP/UDP
- The first stream over RTSP and the second using RTP via udpsink

I saw that when I start RTSP streaming first then RTP stream. The bitrate and also the video quality for 2 streams is kept stable (aacceptable) But in opposite if I start streaming RTP stream first, then RTSP stream, the bitrate of RTSP stream is really bad and also the video quality. It slow, lag...I use the VPU encoder HW in an IMX6 board.

Can anybody explain me the behavior, is there any side affect if I start RTSP stream before RTP stream?

[Nicolas Dufresne-4]

Le jeudi 27 octobre 2016 à 00:08 -0700, Tran Tu a écrit :

> I wrote an application to stream dual streams through RTSP and RTP/UDP
> - The first stream over RTSP and the second using RTP via udpsink
>
> I saw that when I start RTSP streaming first then RTP stream. The bitrate
> and also the video quality for 2 streams is kept stable (aacceptable) But in
> opposite if I start streaming RTP stream first, then RTSP stream, the
> bitrate of RTSP stream is really bad and also the video quality. It slow,
> lag...I use the VPU encoder HW in an IMX6 board.
>
> Can anybody explain me the behavior, is there any side affect if I start
> RTSP stream before RTP stream?

You'll have to clarify a bit more. The stream of an RTSP session is
RTP. Would it be possible to share more details on what you are trying
to do ? As of now, I'm not sure I understand.

Nicolas
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[Tran Tu]

Hi Nicolas,

Thanks for your reply. I would like to describe it more details as below:

I intend to use VPU hardware encoder of IMX6 to encode two streams captured from camera(1 fullhd and 1 wvga)

Fullhd I stream via RTSP server and the second one I stream by RTP/UDP (using udpsink plugin). To do so, I created two threads for streamings (one used gst-rtsp-server to stream fullhd and second is used object model of gstreamer for streaming via RTP).

As my understand RTSP server also use RTP in the background, and I only use one VPU to do encoding.
But the issue here is that, if thread1 with RTSP server start first, then thread2 with RTP start after, the quality of video stream (smoothly, bitrate...) is decreased but a little bit. And in opposite, thread2 start first with RTP streaming, then start thread1 with RTSP server streaming. The video quality is very bad.

All the code is unchanged, I just change the order of streaming execution. It makes me confused about the reason why executing order influenced to to video quality so much.

P/S: Thread1 with RTSP stream for fullHD and the second thread is for wvga

[alxg]

did you get this to work? I'm interested in a similar application :)

Cheers,
Alex