[RFC PATCH v2 00/13] Enable raw streams with software ISP

[Milan Zamazal]

This makes raw streams working again in ‘simple’ pipeline when software
ISP is enabled for the given device.  At most one raw stream and one
processed stream (possibly both at once) are supported.

An example ‘cam’ invocation requesting a raw stream rather than a debayered stream:

  cam -c1 -C8 -s role=raw,width=1920,height=1080 -Ffile#.raw

Or for both raw and processed streams:

  cam -c1 -C8 -s role=raw,width=1920,height=1080,pixelformat=SRGGB8 -s role=viewfinder,width=1920,height=1080,pixelformat=RGB888 -Ffile#

When only a raw stream is requested, there are no exposure/gain
adjustments applied.  This could be improved in future, once software
ISP gets a mechanism to gather image statistics without processing and
using them to make the adjustments, or once manual exposure controls are
added to software ISP.  In the meantime, exposure must be changed
externally.

A part of the patches is a small change to ‘cam’ PPM file handling, to
be able to produce PPM files together with raw files when both processed
and raw streams are requested.

The patches are RFC because I’m not sure whether they are implemented
properly.  It’s also necessary to determine the right balance between
the requested functionality (single raw + processed streams should be
enough for current needs), cleanness of the implementation and the
complexity of the patches.

Changes in v2:
- Completely reworked.
- Extended to be able to produce a raw stream together with a processed
  stream.

Milan Zamazal (13):
  libcamera: software_isp: Move a non-loop condition out of the loop
  libcamera: simple: Increase the default number of streams to 2
  libcamera: simple: Don't use raw output formats with conversions
  libcamera: simple: Add plain output configurations to software ISP
  libcamera: simple: Identify requested stream roles
  libcamera: simple: Protect against null maxPipeConfig
  libcamera: simple: Consider raw output configurations
  libcamera: simple: Handle adjusted and raw configurations separately
  libcamera: simple: Don't use conversion with an added raw stream
  libcamera: simple: Make raw streams working
  apps: ppm_writer: Add a missing include
  apps: ppm_writer: Return EIO on I/O errors
  apps: cam: Write raw file if PPM cannot be written

 src/apps/cam/file_sink.cpp                  |  16 +-
 src/apps/common/ppm_writer.cpp              |   7 +-
 src/libcamera/pipeline/simple/simple.cpp    | 188 ++++++++++++++++----
 src/libcamera/software_isp/software_isp.cpp |   7 +-
 4 files changed, 168 insertions(+), 50 deletions(-)

-- 
2.48.1