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libcamera: v4l2_videodevice: Reintroduce toV4L2PixelFormat()

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This is a partial revert of commit 395d43d6d7 ("libcamera:
v4l2_videodevice: Drop toV4L2PixelFormat()")

The function was removed because it incorrectly maps non-contiguous V4L2
format variants (ie V4L2_PIX_FMT_YUV420M) to the API version supported
by the video device (singleplanar API and multiplanar API).  It was
decided at the time to remove the function and let its users call
directly V4L2PixelFormat::fromPixelFormat() which accepts a
'multiplanar' flags.

As we aim to associate multiple V4L2PixelFormat to a single libcamera
format, the next patches will verify which of them is actually supported
by the video device. For now, return the contiguous version
unconditionally.

Re-introduce V4L2VideoDevice::toV4L2PixelFormat() and convert all
the V4L2PixelFormat::fromPixelFormat() users to use it.

The V4L2 compatibility layer is the only outlier as it doesn't have a
video device to poke, hence it still uses
V4L2PixelFormat::fromPixelFormat().

Next patches will implement the device format matching logic and handle
the non-contiguous plane issue in V4L2VideoDevice::toV4L2PixelFormat().

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Paul Elder <paul.elder@ideasonboard.com>
This commit is contained in:
Jacopo Mondi 2022-07-15 10:50:41 +02:00
parent 83e0cee0ba
commit 45736468c8
12 changed files with 60 additions and 37 deletions
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7
Documentation/guides/pipeline-handler.rst
View file

@ -971,7 +971,8 @@ with the fourcc and size attributes to apply directly to the capture device
node. The fourcc attribute is a `V4L2PixelFormat`_ and differs from the
``libcamera::PixelFormat``. Converting the format requires knowledge of the
plane configuration for multiplanar formats, so you must explicitly convert it
using the helper ``V4L2PixelFormat::fromPixelFormat()``.
using the helper ``V4L2VideoDevice::toV4L2PixelFormat()`` provided by the
V4L2VideoDevice instance that the format will be applied on.
.. _V4L2DeviceFormat: https://libcamera.org/api-html/classlibcamera_1_1V4L2DeviceFormat.html
.. _V4L2PixelFormat: https://libcamera.org/api-html/classlibcamera_1_1V4L2PixelFormat.html
@ -981,7 +982,7 @@ Add the following code beneath the code from above:
.. code-block:: cpp
V4L2DeviceFormat format = {};
format.fourcc = V4L2PixelFormat::fromPixelFormat(cfg.pixelFormat);
format.fourcc = data->video_->toV4L2PixelFormat(cfg.pixelFormat);
format.size = cfg.size;
Set the video device format defined above using the
@ -1001,7 +1002,7 @@ Continue the implementation with the following code:
return ret;
if (format.size != cfg.size ||
format.fourcc != V4L2PixelFormat::fromPixelFormat(cfg.pixelFormat))
format.fourcc != data->video_->toV4L2PixelFormat(cfg.pixelFormat))
return -EINVAL;
Finally, store and set stream-specific data reflecting the state of the stream.