[libcamera-devel] [RFC 0/6] libcamera: Add support for a RAW still capture stream

[Niklas Söderlund]

Hi,

This series is an RFC for how RAW capture can be added to libcamera. It 
implements a RAW stream in the IPU3 pipeline handler as an example. It 
targets RAW still image captures and uses a memcpy to copy out the 
buffer with the RAW data as soon as it's dequeued from the CIO2. The 
copy is needed as the buffer might need to be used in further processing 
by the IMGU.

Patch 1/6 Defines a new StillCaptureRaw role which can be used to 
applications to generate configurations for raw capture. Patch 2/6 makes 
use of this new role in the cam utility.

Patch 3/6 is not ready for consumption as it depends on work submitted 
to the DRM subsystem. The patch is however needed as the new DRM formats 
are needed to describe the IPU3's RAW pixel format.

Patch 4/6 adds a helper to do the actual memcpy of FrameBuffers. I'm not 
really sure it should be declared in buffers.h. Suggestions for a better 
location are welcome.

Patch 5/6 and 6/6 deals with implementing the RAW stream into the IPU3 
pipeline handler.

This series depends on Laruent's work [1] to use the improved 
BufferAllocator with buffer orphaning support. To ease testing [2] may 
also be useful to allow cam to write two capture streams content to disk 
without conflict.

I have tested this on IPU3 and I can capture both a single RAW stream or 
a mix of RAW and video, example with both and writing to disk.

$ ./cam -c1  -s role=video -s role=stillraw -C -F
...
fps: 0.00 stream0 seq: 002055 bytesused: 1382400 stream1 seq: 000001 bytesused: 3269376
fps: 30.30 stream0 seq: 002056 bytesused: 1382400 stream1 seq: 000002 bytesused: 3269376
fps: 30.30 stream0 seq: 002057 bytesused: 1382400 stream1 seq: 000003 bytesused: 3269376
fps: 30.30 stream0 seq: 002058 bytesused: 1382400 stream1 seq: 000004 bytesused: 3269376
...

What I still have to do is find/write a IPU3 RAW frame decoder to verify 
the captured RAW frames are good. So far I verified each captured frame 
have a different checksum and the captured metadata (sequence nr etc) 
make sens.

1. [PATCH 0/9] Simplify buffer management with V4L2 buffer orphaning
2. [PATCH] cam: Create stream names after configuring the camera

Niklas Söderlund (6):
  libcamera: stream: Add StillCaptureRaw role
  cam: Add option to capture StillCaptureRaw stream
  [DNI] include: drm_fourcc: Add Bayer FourCC and modifiers
  libcamera: buffer: Add helper to memcopy a FrameBuffer
  libcamera: ipu3: Do not unconditionally queue buffers to CIO2
  libcamera: ipu3: Add support for a RAW still capture stream

 include/libcamera/buffer.h           |   1 +
 include/libcamera/stream.h           |   1 +
 include/linux/drm_fourcc.h           |  94 +++++++++++++++++
 src/cam/main.cpp                     |   4 +-
 src/libcamera/buffer.cpp             |  43 ++++++++
 src/libcamera/pipeline/ipu3/ipu3.cpp | 152 +++++++++++++++++++++++----
 src/libcamera/stream.cpp             |   4 +
 7 files changed, 279 insertions(+), 20 deletions(-)

-- 
2.25.1