What method can be used to determine the actual bitrate of an incoming RTSP stream using GStreamer?

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1

Can you guide me on how to accurately determine the actual bitrate of an incoming RTSP stream?

I’ve attempted using the “current-level-bytes” property of the queue element in my process, but the outcome was unsatisfactory. Additionally, I experimented with using gst_element_query_duration with GST_FORMAT_BYTES on the rtspsrc element, but it returned a value of 0. Are there any alternative methods or approaches I can employ to calculate the real bitrate of an RTSP stream effectively?

1 Like
2

Hey, Komal Welcome back to the Gumlet community!

To get an accurate reading of an RTSP stream’s bitrate using GStreamer, you might want to try attaching a probe to the sink pad of the rtspsrc element and calculate the bitrate manually. This method involves tracking the data flow through the pad over a certain period. Here’s a basic approach:

Attach a probe to the rtspsrc element’s sink pad using gst_pad_add_probe.

In the callback for the probe, keep tabs on the total data throughput and the time duration.

Utilize the formula: bitrate = (total bytes * 8) / elapsed time in seconds.

This approach should provide a more precise measurement of the stream’s bitrate.

3

That seems like a good approach. Could you elaborate on how to set this up in GStreamer?

4

In GStreamer, you’d use gst_pad_add_probe to add a probe to the sink pad of your rtspsrc element. Within the callback function for this probe, you’d monitor the cumulative data passing through the pad and the time passed since you began recording. These figures are then used to calculate the bitrate.

Here’s a simplified code example:

gst_pad_add_probe(sink_pad, GST_PAD_PROBE_TYPE_BUFFER,
    (GstPadProbeCallback) my_probe_callback, NULL, NULL);

static GstPadProbeReturn my_probe_callback(GstPad *pad, GstPadProbeInfo *info, gpointer user_data) {
    // Update data count
    // Monitor time duration
    // Compute bitrate
    return GST_PAD_PROBE_OK;
}

Make sure your time and data tracking is accurate for precise bitrate calculation.

5

Will this method accurately reflect streams with fluctuating bitrates?

6

Yes, this technique should work well even with variable bitrate streams. Since it calculates the bitrate based on real-time data throughput, it can adapt to changes in the stream’s bitrate.

However, for streams with high variability, keep in mind that momentary bitrate calculations might not represent the average bitrate over an extended time.

You may want to calculate the bitrate over varying intervals for a more rounded understanding of the stream’s bitrate behavior.

7

I understand. And if I need to display this bitrate information as it happens, what’s the best way to do that?

8

Yes, this technique should work well even with variable bitrate streams. Since it calculates the bitrate based on real-time data throughput, it can adapt to changes in the stream’s bitrate. However, for streams with high variability, keep in mind that momentary bitrate calculations might not represent the average bitrate over an extended time.

You may want to calculate the bitrate over varying intervals for a more rounded understanding of the stream’s bitrate behavior.

9

And if I need to display this bitrate information as it happens, what’s the best way to do that?

10

For real-time display, consider updating a user interface element or logging the bitrate at consistent intervals in your probe callback. Depending on your application’s setup, you could use a recurring GStreamer event or a dedicated timer to prompt these updates.

This would allow you to offer a live feed of the bitrate for user interface or monitoring purposes. Just be mindful to ensure that the updating process is streamlined and doesn’t hinder the overall streaming performance.