v4l: Add source change event for colorimetry

Message ID 20200702100017.24700-1-stanimir.varbanov@linaro.org
State New
Headers show
Series
  • v4l: Add source change event for colorimetry
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Commit Message

Stanimir Varbanov July 2, 2020, 10 a.m.
This event indicate that the source colorspace is changed
during run-time. The client has to retrieve the new colorspace
identifiers by getting the format (G_FMT).

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>

---
 .../userspace-api/media/v4l/vidioc-dqevent.rst        | 11 ++++++++++-
 .../userspace-api/media/videodev2.h.rst.exceptions    |  1 +
 include/uapi/linux/videodev2.h                        |  1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

-- 
2.17.1

Comments

Stanimir Varbanov July 2, 2020, 11:52 a.m. | #1
Hi,

Once we have this event there is still open question how the client will
know the data buffer on which the new colorspace is valid/applied.

The options could be:
 * a new buffer flag and
 * some information in the v4l2_event structure.

Thoughts?

On 7/2/20 1:00 PM, Stanimir Varbanov wrote:
> This event indicate that the source colorspace is changed

> during run-time. The client has to retrieve the new colorspace

> identifiers by getting the format (G_FMT).

> 

> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>

> ---

>  .../userspace-api/media/v4l/vidioc-dqevent.rst        | 11 ++++++++++-

>  .../userspace-api/media/videodev2.h.rst.exceptions    |  1 +

>  include/uapi/linux/videodev2.h                        |  1 +

>  3 files changed, 12 insertions(+), 1 deletion(-)

> 

> diff --git a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst

> index a9a176d5256d..3f69c753db58 100644

> --- a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst

> +++ b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst

> @@ -381,7 +381,16 @@ call.

>  	that many Video Capture devices are not able to recover from a temporary

>  	loss of signal and so restarting streaming I/O is required in order for

>  	the hardware to synchronize to the video signal.

> -

> +    * - ``V4L2_EVENT_SRC_CH_COLORIMETRY``

> +      - 0x0002

> +      - This event gets triggered when a colorspace change is detected at

> +	an input. By colorspace change here we include also changes in the

> +	colorspace specifiers (transfer function, Y'CbCr encoding and

> +	quantization). This event can come from an input or from video decoder.

> +	Once the event has been send to the client the driver has to update

> +	the colorspace specifiers internally so that they could be retrieved by

> +	client. In that case queue re-negotiation is not needed as this change

> +	only reflects on the interpretation of the data.

>  

>  Return Value

>  ============

> diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions

> index ca05e4e126b2..54fc21af852d 100644

> --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions

> +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions

> @@ -492,6 +492,7 @@ replace define V4L2_EVENT_CTRL_CH_FLAGS ctrl-changes-flags

>  replace define V4L2_EVENT_CTRL_CH_RANGE ctrl-changes-flags

>  

>  replace define V4L2_EVENT_SRC_CH_RESOLUTION src-changes-flags

> +replace define V4L2_EVENT_SRC_CH_COLORIMETRY src-changes-flags

>  

>  replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`

>  

> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h

> index 303805438814..b5838bc4e3a3 100644

> --- a/include/uapi/linux/videodev2.h

> +++ b/include/uapi/linux/videodev2.h

> @@ -2351,6 +2351,7 @@ struct v4l2_event_frame_sync {

>  };

>  

>  #define V4L2_EVENT_SRC_CH_RESOLUTION		(1 << 0)

> +#define V4L2_EVENT_SRC_CH_COLORIMETRY		(1 << 1)

>  

>  struct v4l2_event_src_change {

>  	__u32 changes;

> 


-- 
regards,
Stan

Patch

diff --git a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst
index a9a176d5256d..3f69c753db58 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst
@@ -381,7 +381,16 @@  call.
 	that many Video Capture devices are not able to recover from a temporary
 	loss of signal and so restarting streaming I/O is required in order for
 	the hardware to synchronize to the video signal.
-
+    * - ``V4L2_EVENT_SRC_CH_COLORIMETRY``
+      - 0x0002
+      - This event gets triggered when a colorspace change is detected at
+	an input. By colorspace change here we include also changes in the
+	colorspace specifiers (transfer function, Y'CbCr encoding and
+	quantization). This event can come from an input or from video decoder.
+	Once the event has been send to the client the driver has to update
+	the colorspace specifiers internally so that they could be retrieved by
+	client. In that case queue re-negotiation is not needed as this change
+	only reflects on the interpretation of the data.
 
 Return Value
 ============
diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
index ca05e4e126b2..54fc21af852d 100644
--- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
+++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
@@ -492,6 +492,7 @@  replace define V4L2_EVENT_CTRL_CH_FLAGS ctrl-changes-flags
 replace define V4L2_EVENT_CTRL_CH_RANGE ctrl-changes-flags
 
 replace define V4L2_EVENT_SRC_CH_RESOLUTION src-changes-flags
+replace define V4L2_EVENT_SRC_CH_COLORIMETRY src-changes-flags
 
 replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`
 
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 303805438814..b5838bc4e3a3 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -2351,6 +2351,7 @@  struct v4l2_event_frame_sync {
 };
 
 #define V4L2_EVENT_SRC_CH_RESOLUTION		(1 << 0)
+#define V4L2_EVENT_SRC_CH_COLORIMETRY		(1 << 1)
 
 struct v4l2_event_src_change {
 	__u32 changes;