[libcamera-devel] gstreamer libcamerasrc to v4l2h264enc hardware encoder

[Xishan Sun]

I am trying to link libcamerasrc with v4l2h264enc to use hardware encoder
on Raspberry Pi.

1) if I directly feed into v4l2h264enc with something like:

gst-launch-1.0 libcamerasrc ! video/x-raw,width=1600,height=1200 !
v4l2h264enc ! h264parse ! rtph264pay name=pay0 pt=96 ! fakesink

gstreamer will complain that format cannot be transformed. debug info:

...
0:00:00.671398274 22045  0x12d5400 WARN           basetransform
gstbasetransform.c:1355:gst_base_transform_setcaps:<capsfilter0> transform
could not transform video/x-raw, format=(string)NV21, width=(int)1600,
height=(int)1200 in anything we support
0:00:00.671467254 22045  0x12d5400 WARN            libcamerasrc
gstlibcamerasrc.cpp:321:gst_libcamera_src_task_run:<libcamerasrc0> error:
Internal data stream error.
0:00:00.671491235 22045  0x12d5400 WARN            libcamerasrc
gstlibcamerasrc.cpp:321:gst_libcamera_src_task_run:<libcamerasrc0> error:
streaming stopped, reason not-negotiated (-4)
...

it is strange that
gst-inspect-1.0 v4l2h264enc
shows me that  v4l2h264enc accepts NV21 or NV12 format:

...
Pad Templates:
  SINK template: 'sink'
    Availability: Always
    Capabilities:
      video/x-raw
                 format: { (string)I420, (string)YV12, (string)NV12,
(string)NV21, (string)RGB16, (string)RGB, (string)BGR, (string)BGRx,
(string)BGRA, (string)YUY2, (string)YVYU, (string)UYVY }
                  width: [ 1, 32768 ]
                 height: [ 1, 32768 ]
              framerate: [ 0/1, 2147483647/1 ]
...

 2) if I add videoconvert into pipeline as:
  gst-launch-1.0 libcamerasrc ! video/x-raw,width=1600,height=1200 !
videoconvert ! v4l2h264enc ! h264parse ! rtph264pay name=pay0 pt=96 !
fakesink
then everything works just fine at the beginning. However after I insert
the pipeline into a RTSP server with long term run (about 4-5 hours)  I
see Segmentation fault like:
...
Thread 13 "pool" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb4ce23a0 (LWP 6879)]
std::_Rb_tree<libcamera::Stream*, std::pair<libcamera::Stream* const,
libcamera::FrameBuffer*>, std::_Select1st<std::pair<libcamera::Stream*
const, libcamera::FrameBuffer*> >, std::less<libcamera::Stream*>,
std::allocator<std::pair<libcamera::Stream* const, libcamera::FrameBuffer*>
> >::_M_lower_bound (this=0xb4316690, __x=0x517060b, __y=0xb4316694,
__k=@0xb4ce1728: 0xb4319060) at /usr/include/c++/8/bits/stl_tree.h:1904
1904 if (!_M_impl._M_key_compare(_S_key(__x), __k))
...

Question:
1) Can we have libcamerasrc output direct to v4l2h264enc without
videoconvert? If we can define "output-io-mode" of libcamerasrc into
"dmabuf", it would be even better.
2) is that with videoconvert the best solution right now? I tried
v4l2convert and it didn't work. I think libcamerasrc is already using the
device.

Thanks,

-- 
Xishan Sun
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