Pipeline's configured latency remains GST_CLOCK_TIME_NONE

General Discussion
1

Hi everybody.
I have this pipeline in my application

channel_ppln
channel_ppln2780×364 84.5 KB
.
And I’m trying to trace the latencies of all its elements and pipeline as well along with the entire buffer flow (timestamp of the buffer when it arrives on the certain pad, pts/dts etc).
What I can see:

  1. intervideosink posts LATENCY message on the bus requesting to (re)configure pipeline’s latency:
    busCallBack: GST_MESSAGE_LATENCY: intervideosink0
  2. Then I see that GST_EVENT_LATENCY event is received on sink pad of the intervideosink element:
    eventProbe: GST_EVENT_LATENCY: 31
  3. So, I assume here that pipeline’s latency would be (re)configured to value 31
  4. When the whole pipeline swithes to the PLAYING state I query all latencies (the format is isLive, [min_latency, max_ltency]:
    queryLatency: v4l2src0: 1, [16, 533]
    queryLatency: jpegdec0: 1, [16, 533]
    queryLatency: identity0: 1, [16, 533]
    queryLatency: intervideosink0: 1, [31, 533]
    queryLatency: pipeline0: 1, [31, 533]
    So, according to the official gst docs the requested latency value for the pipeline 31 seems to be correct. But right after that I check the pipeline’s configured latency with the gst_pipeline_get_configured_latency function and it returns GST_CLOCK_TIME_NONE. Why?
    And if I check configured latency of intervideosink with gst_base_sink_get_latency I get 31…
  5. Then I install buffer probe on sink pad of the intervideosink element and check pts/dts, duration, offsets, running time and latency of the pipeline and here is what I get:
    onBuffer: intervideosink0 sink: dts: NaN, pts: 2978, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3002, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 2994, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3019, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 3010, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3035, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 3026, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3051, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 3046, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3066, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 3062, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3084, ppln latency: 18446744073709
    onBuffer: intervideosink0 sink: dts: NaN, pts: 3078, dur: 16, offset: NaN, offset-end: NaN, live: 1, min_l: 31, max_l: 533, runTime: 3103, ppln latency: 18446744073709
    So, pipeline’s latency remains GST_CLOCK_TIME_NONE for ever… Why?

P.S. All logs (in italic) are my custom logs

2

Hi @Vovamulder

Could you please try enabling the GStreamer tracers?

I tried the following pipeline:

GST_TRACERS="latency(flags=pipeline+element+reported)" GST_DEBUG=GST_TRACER:7 gst-launch-1.0 -v videotestsrc ! intervideosink intervideosrc ! videoconvert ! xvimagesink

And got the following output:

0:00:00.377769412 39462 0x5a7827a75cc0 TRACE             GST_TRACER :0:: latency, src-element-id=(string)0x5a782787a6e0, src-element=(string)intervideosrc0, src=(string)src, sink-element-id=(string)0x5a7827857b30, sink-element=(string)xvimagesink0, sink=(string)sink, time=(guint64)469532, ts=(guint64)377757010;
0:00:00.377786970 39462 0x5a7827a75cc0 TRACE             GST_TRACER :0:: element-latency, element-id=(string)0x5a7827a5ced0, element=(string)videoconvert0, src=(string)src, time=(guint64)469532, ts=(guint64)377757010;

The latency seems to be the time value since:

| src | -> |convert (469532) | -> | sink |

Regards!