Do GStreamer handle loss of key frames (H264)?

[Marcos Kintschner]

I'm trying to understand if and how GStreamer handle a lost IDR frame.

I know there is an event called GstForceKeyUnit that is sent by rtph264depay when this element receives data before setting SPS/PPS and that this event is then processed by rtpsession that generates a RTCP/PLI message. But it seems that rtph264depay doens't send the event when it receives a P-Slice before a IDR-Slice, for example. Do I have to handle it manually by adding probes and checking if the IDR has arrived or not?

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[Nicolas Dufresne-5]

Le mercredi 26 septembre 2018 à 01:19 -0300, Marcos Kintschner a
écrit :
> I'm trying to understand if and how GStreamer handle a lost IDR
> frame.
> I know there is an event called GstForceKeyUnit that is sent by
> rtph264depay when this element receives data before setting SPS/PPS
> and that this event is then processed by rtpsession that generates a
> RTCP/PLI message. But it seems that rtph264depay doens't send the
> event when it receives a P-Slice before a IDR-Slice, for example. Do
> I have to handle it manually by adding probes and checking if the IDR
> has arrived or not?

I don't see "initial" trigger. It only do that on packet lost. It seems
like a good idea to add rather then having to do this manually.

>
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> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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[Marcos Kintschner]

Do you have any advice from where should I start looking it? I think we could add an option (disabled by default) to check for picture loss in rtph264depay or h264parse to make it "implementation agnostic", so one could use it for avdec_h264 or other decoders. 

Em qua, 26 de set de 2018 às 01:19, Marcos Kintschner <[hidden email]> escreveu:

I'm trying to understand if and how GStreamer handle a lost IDR frame.

I know there is an event called GstForceKeyUnit that is sent by rtph264depay when this element receives data before setting SPS/PPS and that this event is then processed by rtpsession that generates a RTCP/PLI message. But it seems that rtph264depay doens't send the event when it receives a P-Slice before a IDR-Slice, for example. Do I have to handle it manually by adding probes and checking if the IDR has arrived or not?

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[Nicolas Dufresne-5]

Le ven. 28 sept. 2018 13 h 58, Marcos Kintschner <[hidden email]> a écrit :

Do you have any advice from where should I start looking it? I think we could add an option (disabled by default) to check for picture loss in rtph264depay or h264parse to make it "implementation agnostic", so one could use it for avdec_h264 or other decoders.

RTP packet loss should catch all losses, parsing that much the stream in h264parse is quite some overhead.

What I had in mind is that rtph264depay could simply send the keyframe event on discont unless we have a valid header sequence ([AUD], pps, sps, [sei], IDR slice). It could also drop the data before pps/sps like h264parse is doing.

Em qua, 26 de set de 2018 às 01:19, Marcos Kintschner <[hidden email]> escreveu:

I'm trying to understand if and how GStreamer handle a lost IDR frame.

I know there is an event called GstForceKeyUnit that is sent by rtph264depay when this element receives data before setting SPS/PPS and that this event is then processed by rtpsession that generates a RTCP/PLI message. But it seems that rtph264depay doens't send the event when it receives a P-Slice before a IDR-Slice, for example. Do I have to handle it manually by adding probes and checking if the IDR has arrived or not?

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