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

[Laurent Pinchart]

Hi Milan,

On Fri, Jan 24, 2025 at 10:57:51PM +0100, Milan Zamazal wrote:
> 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.

This is fine.

> 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.

The famous yak shaving balance.

As you'll see in the review of individual patches, I think there's some
cleanup to be done. The good news is that we don't need a full yak
shaving, just trimming some edges :-)

> 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(-)

-- 
Regards,

Laurent Pinchart