Appsink stops (pauses/freezes) after 2 frames.

[Hjalmar Turesson]

Hi,

I tested the same code on my laptop using the in-built camera, and it
worked fine. The camera supports the same formats except for H264.
I.e. (laptop webcam):
$ v4l2-ctl --list-formats
ioctl: VIDIOC_ENUM_FMT
    Index       : 0
    Type        : Video Capture
    Pixel Format: 'YUYV'
    Name        : YUV 4:2:2 (YUYV)

    Index       : 1
    Type        : Video Capture
    Pixel Format: 'MJPG' (compressed)
    Name        : MJPEG

However, the camera I want to use is a Logitech C920 webcam. What is the
difference? Why does it work on one camera but not on the other (even
though it works when streaming h264)?

Best regards,
Hjalmar

On Fri, Mar 27, 2015 at 12:12 PM, Hjalmar Turesson <hturesson at gmail.com>
wrote:

> Thanks for the advice Arjen.
>
> I tried setting the format. It doesn't seem to help. I used format=YUV2,
> which I think corresponds to Pixel Format: 'YUYV'. In either case, it
> doesn't seem critical, bc when I change sink to a filesink (encode and save
> the stream), it works fine.
>
> $ v4l2-ctl --list-formats
> ioctl: VIDIOC_ENUM_FMT
>     Index       : 0
>     Type        : Video Capture
>     *Pixel Format: 'YUYV'*
>     Name        : YUV 4:2:2 (YUYV)
>
>     Index       : 1
>     Type        : Video Capture
>     Pixel Format: 'H264' (compressed)
>     Name        : H.264
>
>     Index       : 2
>     Type        : Video Capture
>     Pixel Format: 'MJPG' (compressed)
>     Name        : MJPEG
>
> I've looked at the debug output but it doesn't say much (at least not to
> me). GST_DEBUG='3' does nothing. At 4 I see a lot, but no errors or
> warnings. The last line is completely normal:
> 0:00:11.181339628 13055      0x2f6e850 INFO                 v4l2src
> gstv4l2src.c:737:gst_v4l2src_create:<v4l2src0> sync to 0:00:00.133333332
> out ts 0:00:00.287874714
>
> At debug threshold 5 I just don't understand much anymore. The last few
> lines look like this:
> 0:00:31.297802714 12103      0x3d79c50 DEBUG               basesink
> gstbasesink.c:2114:gst_base_sink_wait_clock:<appsink0> sync disabled
> 0:00:31.297813795 12103      0x3d79c50 DEBUG               basesink
> gstbasesink.c:2489:gst_base_sink_do_sync:<appsink0> clock returned 4,
> jitter  0:00:00.000000000
> 0:00:31.297828235 12103      0x3d79c50 DEBUG               basesink
> gstbasesink.c:3411:gst_base_sink_chain_unlocked:<appsink0> rendering object
> 0x3aa0780
> 0:00:31.297840457 12103      0x3d79c50 DEBUG               basesink
> gstbasesink.c:936:gst_base_sink_set_last_buffer_unlocked:<appsink0> setting
> last buffer to 0x3aa0780
> 0:00:31.297853893 12103      0x3d79c50 DEBUG                appsink
> gstappsink.c:710:gst_app_sink_render:<appsink0> pushing render buffer
> 0x3aa0780 on queue (0)
> 0:00:31.297892613 12103      0x3d79c50 DEBUG                appsink
> gstappsink.c:1181:gst_app_sink_pull_sample:<appsink0> trying to grab a
> buffer
> 0:00:31.297907333 12103      0x3d79c50 DEBUG                appsink
> gstappsink.c:656:dequeue_buffer:<appsink0> dequeued buffer 0x3aa0780
> 0:00:31.297919138 12103      0x3d79c50 DEBUG                appsink
> gstappsink.c:1196:gst_app_sink_pull_sample:<appsink0> we have a buffer
> 0x3aa0780
> 0:00:31.298086959 12103      0x3d79c50 DEBUG               basesink
> gstbasesink.c:3450:gst_base_sink_chain_unlocked:<appsink0> object unref
> after render 0x3aa0780
> 0:00:31.298110134 12103      0x3d79c50 DEBUG                basesrc
> gstbasesrc.c:2441:gst_base_src_get_range:<v4l2src0> calling create offset
> 18446744073709551615 length 4096, time 0
> 0:00:31.298126123 12103      0x3d79c50 DEBUG                   v4l2
> gstv4l2bufferpool.c:1146:gst_v4l2_buffer_pool_acquire_buffer:<v4l2src0:pool:src>
> acquire
>
>
>
> On Fri, Mar 27, 2015 at 6:09 AM, Arjen Veenhuizen <arjen.veenhuizen at tno.nl
> > wrote:
>
>> Dome pointers:
>> * Did you check the GST debug logs (e.g. export GST_DEBUG-3 or 4).
>> * Perhaps you need to specify the stream format as well in the capsfilter.
>> (E.g. I420 or something)
>>
>> Hjalmar Turesson wrote
>> >  I tried using videoparse, but this crashes python
>>
>> This is not what I would have expected. I guess the pipeline stalls and
>> the
>> python program becomes unresponsive, possibly due to a caps negotiation
>> problem.
>> Please inspect and/or share your GStreamer logs.
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://gstreamer-devel.966125.n4.nabble.com/Appsink-stops-pauses-freezes-after-2-frames-tp4671355p4671356.html
>> Sent from the GStreamer-devel mailing list archive at Nabble.com.
>> _______________________________________________
>> gstreamer-devel mailing list
>> gstreamer-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>
>
>
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