problem with v4l2src

[Nicolas Dufresne]

Le lundi 04 février 2019 à 06:28 -0600, tobatrance a écrit :
> Hi,
> 
> I got a problem with my v4l2 pipeline. I'm using this one in my application:
> 
> v4l2src ! "video/x-raw, framerate=60/1" ! appsink
> 
> I'm fetching frames from a USB HDMI connector which is listed as working
> properly with uvcvideo. However,  after some time of working it happens that
> I get the following warning in my log:
> 
> 0:00:23.829022849  1063 0x557125fe6e30 WARN                 v4l2src
> gstv4l2src.c:968:gst_v4l2src_create:<v4l2src> lost frames detected: count =
> 10 - ts: 0:00:00.019533643
> 0:12:08.112411028  1063 0x557125fe6e30 WARN           v4l2allocator
> gstv4l2allocator.c:1351:gst_v4l2_allocator_dqbuf:<v4l2src:pool:src:allocator>
> V4L2 provided buffer has bytesused 0 which is too small to include
> data_offset 0
> 0:12:08.112455447  1063 0x557125fe6e30 WARN          v4l2bufferpool
> gstv4l2bufferpool.c:1946:gst_v4l2_buffer_pool_process:<v4l2src:pool:src>
> Dropping corrupted buffer without payload
> 
> while the last 2 messages are repeated a couple of times. After that the
> streaming immediately stops.

The initial warning indicates that the src have run out of buffers.
Your application is not returning the buffers fast enough. The second
is a kernel bug that was fixed recently. There is worked around in
latest GStreamer stable 1.14.4 if I remember well.

> 
> this happens in 1.8.3 and 1.14.1. Any idea or better recommendation how to
> fix that?

You can of course upgrade your kernel, but you could also ensure you
don't starve the source. You could copy and return immediately the
frames (the would not be zero copy) or you could use a pad probe to
intercept the allocation query and request more buffers to be
allocated.

> 
> 
> 
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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