AW: Multiple pipelines in an application

[Thornton, Keith]

I forgot to mention that the elements sould have unique names.

-----Ursprüngliche Nachricht-----
Von: gstreamer-devel [mailto:gstreamer-devel-bounces at lists.freedesktop.org] Im Auftrag von Hannes Weisbach
Gesendet: Freitag, 21. August 2015 11:45
An: gstreamer-devel at lists.freedesktop.org
Betreff: Multiple pipelines in an application

Hello,

I'm writing an application which handles two video streams from USB video class devices, which runs on the Raspberry Pi.  The cameras stream H.264.  The application needs to store a high-quality version locally on disk (using filesink).  Additionally a downscaled, lower quality RTP stream should be provided.  Decompression and compression is done using the Raspberry's hardware acceleration (with gst-omx).  I have implemented the streams using qt-gstreamer.

Right now my application has two pipelines, one for each camera stream.  Occasionally, the program crashes, around the time the second pipeline goes into playing state.

After a bit of googling I found an old message from this list [0], saying that multiple pipelines in one application are not easily doable.  I was wondering if that limitation still applies, or if I have a bug somewhere else.

Launching my application in gdb lets the segfault trigger even less often, suggesting some kind of race condition.  When I caught a crash in gdb, the crashing function was reported as video_orc_unpack_I420.
However, the function was called with broken parameters (way too large n), so the cause might be elsewhere.  Also the stack seemed to be corrupted.

Anyway, I had no problems running just one pipeline in my application, so I'd appreciate a comment on whether its possible/advisable to have multiple pipelines in an application or if I should refactor to have only one pipeline (and possible start two instances of the application).

Thank you for your time,
with best regards,
Hannes Weisbach

[0] http://lists.freedesktop.org/archives/gstreamer-devel/2006-June/012599.html
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