Troubleshooting gst-launch freezes/hangs - how?

[Graham Leggett]

On 05 Aug 2015, at 12:56 AM, Thiago Santos <thiagoss at osg.samsung.com> wrote:

> You can use GST_DEBUG to generate logs of the run, but a run of hours can generate a massively large dump. You can try to guess which elements are involved to not have to log everything. Something like:
> 
> GST_DEBUG=2,*hls*:9,*mpeg*:9,GST_SCHEDULING:9 will give some information about the buffers flowing from pads to pads and also what the hls and mpeg elements are doing.

I tried limiting the debug level to 1 to limit the output to errors only, and I’ve uncovered another clue.

Running two gstreamer pipelines against the same multicast stream on two separate Pis, both pipelines freeze at the same time. In both cases, the pipelines suddenly report "Redistribute latency…” and then freeze almost immediately afterwards.

The message appears twice in the source code, but both times the message precedes the following line of code:

      case GST_MESSAGE_LATENCY:
      {
        PRINT (_("Redistribute latency...\n"));
        gst_bin_recalculate_latency (GST_BIN (pipeline));
        break;
      }

Can anyone confirm what gst_bin_recalculate_latency() does (over and above recalculating the latency) and whether there is anything in this code that would derail a streamer pipeline?

First Pi:

0:07:30.504780606  8890   0x66e0f0 ERROR            omxvideoenc gstomxvideoenc.c:1553:gst_omx_video_enc_handle_frame:<omxh264enc-omxh264enc0> Failed to force a keyframe: Unsupported index (0x8000101a)
Redistribute latency...
progressreport0 (00:07:35): 454 seconds
progressreport1 (00:07:35): 454 seconds
progressreport2 (00:07:35): 454 seconds

Second Pi:

0:07:30.883863816  7974   0x6932f0 ERROR            omxvideoenc gstomxvideoenc.c:1553:gst_omx_video_enc_handle_frame:<omxh264enc-omxh264enc0> Failed to force a keyframe: Unsupported index (0x8000101a)
progressreport0 (00:07:35): 454 seconds
progressreport1 (00:07:35): 454 seconds
progressreport2 (00:07:35): 454 seconds
Redistribute latency...
progressreport0 (00:07:40): 459 seconds
progressreport1 (00:07:40): 459 seconds

Regards,
Graham
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