Why gstreamer pipeline fails when using v4l2src format as BGR and io-mode as dmabuf?

[Nicolas Dufresne]

Le mer. 5 déc. 2018 00 h 26, harikrishnan <hari.vinu.4 at gmail.com> a écrit :

> I am using gstreamer version 1.8.3 on ubunutu 16.04 LTS.
> I am trying to run a pipeline using gst-launch-1.0 with the following
> command on terminal.(which streams webcam video in my laptop)
> Command:
> gst-launch-1.0 -v v4l2src io-mode=4 ! video/x-raw,format=BGR ! videoconvert
> ! autovideosink --gst-debug=2
>

Packed BGR 24bit is a libv4l2 emulated format. It is rarely supported by
HW. DmABuf can only be used with HW supported formats.


> And i am getting the debug messages
> "
> 0:00:00.682056977  4806      0x1c624a0 ERROR               fdmemory
> gstfdmemory.c:114:gst_fd_mem_map: 0x1c5d5f0: fd 20: mmap failed: Invalid
> argument
> 0:00:00.682092724  4806      0x1c624a0 ERROR             GST_MEMORY
> gstmemory.c:324:gst_memory_map: mem 0x1c5d5f0: subclass map failed
> 0:00:00.682124299  4806      0x1c624a0 ERROR               fdmemory
> gstfdmemory.c:114:gst_fd_mem_map: 0x1c5d5f0: fd 20: mmap failed: Invalid
> argument
> 0:00:00.682138286  4806      0x1c624a0 ERROR             GST_MEMORY
> gstmemory.c:324:gst_memory_map: mem 0x1c5d5f0: subclass map failed
> 0:00:00.682152551  4806      0x1c624a0 ERROR                default
> video-frame.c:161:gst_video_frame_map_id: failed to map video frame plane 0
> 0:00:00.682171269  4806      0x1c624a0 WARN             videofilter
> gstvideofilter.c:292:gst_video_filter_transform:<videoconvert0> warning:
> invalid video buffer received
> WARNING: from element /GstPipeline:pipeline0/GstVideoConvert:videoconvert0:
> Internal GStreamer error: code not implemented.  Please file a bug at
> http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer.
> Additional debug info:
> gstvideofilter.c(292): gst_video_filter_transform ():
> /GstPipeline:pipeline0/GstVideoConvert:videoconvert0:
> invalid video buffer received
> "
>
> But the same pipeline works if I change the format=YUY2.
> Working Command:
> gst-launch-1.0 -v v4l2src io-mode=4 ! video/x-raw,format=YUY2 !
> videoconvert
> ! autovideosink --gst-debug=2
>
> From the debug messages I found that mmap fails when using BGR format and
> dmabuf.
>
> I suspected the size of data to mmap. In case of BGR it was 2.7 MB to mmap
> and in case of YUY2 it was 1.8 MB for one frame buffer.
> So I hardcorded the BGR size to 1.8 MB just before doing mmap. Then mmap
> did
> not throw any errors but obviously pipeline broke at some other point since
> it will make data invalid.
>
> Can someone help me on this issue? I want to build a pipeline with BGR
> format as output from v4l2src and it should use dmabuf as io-mode.
>
>
>
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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