Hi Nicolas,
Thanks for reviewing.
On 9/11/24 19:12, Nicolas Dufresne wrote:
Hi Hugues,
Le mercredi 11 septembre 2024 à 15:50 +0200, Hugues Fruchet a écrit :
Add a flag indicating that VP8 bitstream is a WebP picture.
Sounds like there should be some code changes in GStreamer that you haven't
disclosed. Mind sharing how this new uAPI is used ? I would also expect this
commit message to give more insight on what is special about WebP that makes
this flag required.
GStreamer changes here:
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/commit/138ecfac54ce85b273a26ff6f0fefe3998f8d436?merge_request_iid=7505
Verisilicon datasheet is not explicit on why WebP must be signaled to
hardware but WebP decoding fails if not.
Seems to me that such a simple addition on an already existing flag is
something acceptable and preferable to the development of a new complete
uAPI for WebP decoding.
I would also need some more API or documentation that explain how we can
differentiate a upstream decoder that is capable of WebP decoding from one that
does not. I wonder if it would not have been better to define a new format ?
That being said, I haven't looked at all in the specification and only rely on
your cover letter and patch series.
Nicolas
Signed-off-by: Hugues Fruchet <hugues.fruchet@xxxxxxxxxxx>
---
.../userspace-api/media/v4l/ext-ctrls-codec-stateless.rst | 3 +++
include/uapi/linux/v4l2-controls.h | 1 +
2 files changed, 4 insertions(+)
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
index 0da635691fdc..bb08aacddc9c 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
@@ -1062,6 +1062,9 @@ FWHT Flags
* - ``V4L2_VP8_FRAME_FLAG_SIGN_BIAS_ALT``
- 0x20
- Sign of motion vectors when the alt frame is referenced.
+ * - ``V4L2_VP8_FRAME_FLAG_WEBP``
+ - 0x40
+ - Indicates that this frame is a WebP picture.
.. c:type:: v4l2_vp8_entropy_coder_state
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index 974fd254e573..e41b62f2cb2b 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -1897,6 +1897,7 @@ struct v4l2_vp8_entropy_coder_state {
#define V4L2_VP8_FRAME_FLAG_MB_NO_SKIP_COEFF 0x08
#define V4L2_VP8_FRAME_FLAG_SIGN_BIAS_GOLDEN 0x10
#define V4L2_VP8_FRAME_FLAG_SIGN_BIAS_ALT 0x20
+#define V4L2_VP8_FRAME_FLAG_WEBP 0x40
#define V4L2_VP8_FRAME_IS_KEY_FRAME(hdr) \
(!!((hdr)->flags & V4L2_VP8_FRAME_FLAG_KEY_FRAME))
BR,
Hugues.
