RTP timestamps in AppSink

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RTP timestamps in AppSink

Frederik Leth
Hi,
Is it possible to get the RTP timestamps from the buffer in the appsink element ?
I have read, that if the RtpBin is in 'buffer-none' the PTS should contain the RTP timestamp.
PTS timestamp is 8 bytes whereas RTP timestamp is 4 bytes ?
When I run my program the timestamps from PTS is not the same I see in wireshark on the incomming packets.

Best Regards,
Frederik

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Re: RTP timestamps in AppSink

aasim
can you share the code for better understanding of problem.

i used to do this to set video PTS.
                GstBuffer *gstbuf;
                GstMapInfo map = {0};
                GstFlowReturn ret;
                gtbuf->pts = thiz->timestamp;
                thiz->timestamp += 33333333; // ns



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Re: RTP timestamps in AppSink

Tim Müller
In reply to this post by Frederik Leth
On Thu, 2018-02-01 at 11:09 +0100, Frederik Leth wrote:

Hi Frederik,

> Is it possible to get the RTP timestamps from the buffer in the
> appsink element ?
> I have read, that if the RtpBin is in 'buffer-none' the PTS should
> contain the RTP timestamp.
> PTS timestamp is 8 bytes whereas RTP timestamp is 4 bytes ?
> When I run my program the timestamps from PTS is not the same I see
> in wireshark on the incomming packets.

What is the data you are getting in the appsink? Is it RTP packets, or
are you talking about the depayloaded/decoded data and want to know
what the original RTP timestamp was?

If it's RTP packets you could use gst_rtp_buffer_map() +
gst_rtp_buffer_get_timestamp().

Cheers
 -Tim

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Tim Müller, Centricular Ltd - http://www.centricular.com
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Re: RTP timestamps in AppSink

Frederik
The data is raw data. In this case it's depayloaded and decoded audio or
video.
My setup is:
A device delivers an audio and a video stream (on seperate SSRC). The device
creates timestamps for both audio and video, so the two sources are in sync
when leaving the device.
The receiver is a gstreamer, which decodes etc. Both streams ends in it's
own appsink.
An application consumes both appsinks, and at this point I need to sync the
two streams. That is why I wan't to maintain the RTP timestamp created on
the producers (device)
Does this makes sense ??



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Re: RTP timestamps in AppSink

Frederik
In reply to this post by aasim
In my reply to Tim, you can read how the setup of the pipelines are.
Here's the appSink code

static GstFlowReturn on_new_buffer(GstElement* object, gpointer user_data)
{
        GstAppSink* app_sink = (GstAppSink*)object;
        GstSample* sample = gst_app_sink_pull_sample(app_sink);
        if (sample)
        {
                GstBuffer* buffer = gst_sample_get_buffer(sample);
                GstClockTime timestamp = GST_BUFFER_PTS(buffer);
                //this timestamp is not the same as the RTP timestamp
                GstMapInfo map;
                gst_buffer_map(buffer, &map, GST_MAP_READ);
                PipeContext*  context = (PipeContext*)user_data;
                context->PublishAppSink(map.data, map.size, timestamp);

                gst_buffer_unmap(buffer, &map);
                gst_sample_unref(sample);
        }
        return GST_FLOW_OK;
}




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