input-selector pixelation when changing active-pad

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input-selector pixelation when changing active-pad

jaime
Hi,

I have two h264 encoded rtsp sources from IP cameras, and I want to switch
between cameras every 20 seconds, and save the output into a file.  The
problem I face is when switching, I'm expecting a fast switch but it does a
slow pixelated transition between the previous active pad frames and the new
one.

The pipeline looks like:

rtspsrc -> queue -> depay -> input selector -> h264parse -> flvmux ->
filesink

I tried all the input-selector property combinations; cache-buffers
(TRUE|FALSE), sync-streams (TRUE | FALSE), sync-mode (0|1) with no different
results

I also tried:

rtspsrc -> queue -> depay -> h264parse -> input selector -> flvmux ->
filesink

With no different results either.

The libraries Gstreamer 1.8.3 on Ubuntu 16.04 LTS

Could you please shed some light here?


With regards



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Re: input-selector pixelation when changing active-pad

ShilVin
Hi Jaime,

You cannot switch between 2 video elementary stream. Unlike audio NALs, video NALs are not independently decoded. Video is generally ecncode in the form 

I B B P B B P B B P B B P B B P I B B P B B

P and B video frames can't be decoded without I and its dependent reference frame. When stream switches, it breaks dependency and produce pixelated video stream. 

To avoid this consider decoding stream and switch the raw frames.   

 



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On Friday, 6 July, 2018, 3:57:00 PM IST, jaime <[hidden email]> wrote:


Hi,

I have two h264 encoded rtsp sources from IP cameras, and I want to switch
between cameras every 20 seconds, and save the output into a file.  The
problem I face is when switching, I'm expecting a fast switch but it does a
slow pixelated transition between the previous active pad frames and the new
one.

The pipeline looks like:

rtspsrc -> queue -> depay -> input selector -> h264parse -> flvmux ->
filesink

I tried all the input-selector property combinations; cache-buffers
(TRUE|FALSE), sync-streams (TRUE | FALSE), sync-mode (0|1) with no different
results

I also tried:

rtspsrc -> queue -> depay -> h264parse -> input selector -> flvmux ->
filesink

With no different results either.

The libraries Gstreamer 1.8.3 on Ubuntu 16.04 LTS

Could you please shed some light here?


With regards



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Re: input-selector pixelation when changing active-pad

jaime
Thank you for your response.

I will give it a try and let you know.

My only worry is our device (quite small to contain price), could not handle
the encoding load.

Regards



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Re: input-selector pixelation when changing active-pad

Arjen Veenhuizen
You could also switch on I-frame boundaries only. This will require a bit of
programming though, checking each passing buffer on your first feed for the
Gst::BUFFER_FLAG_DELTA_UNIT flag. If I-frames are not aligned between
streams, you will have to wait for a passing i-frame on the second stream as
well.



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Re: input-selector pixelation when changing active-pad

ShilVin
@Arjen Veenhuizen good thought. In that case Use pad probe can be used to
determine the incoming frame type.



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