| Message ID | 20220218184208.455488-1-nicolas.dufresne@collabora.com |
|---|---|
| State | Accepted |
| Commit | 0f6146d476fc99862899e70f2554ee77b444b7b9 |
| Headers | show |
| Series | [v1] media: v4l2-core: Initialize h264 scaling matrix | expand |
Il 18/02/22 19:42, Nicolas Dufresne ha scritto: > In the final H264 API, it is not required to set scaling matrix if > they are not present in the bitstream. A flag was added in order to let > the driver know. The downside is that it leaves the default control > value to 0, which isn't valid. As per the spec (see formulas 7-8/7-9), > when the scaling matrix are absent from the bitstream, flat values > of 16 should be used. This improves this control semantic in a way > that the control value are always valid. Drivers can then use > the scaling_matrix control values without having to check its presence. > Same method was employed for MPEG2_QUANTISATION. > > This fixes issues with MTK VCODEC H264 decoder when using GStreamer. > GStreamer does not set this control if its not present in the bitstream. > As MTK VDCODEC was using the initialized to 0 values, the frames ended > up completely gray. > > Fixes: 54889c51b833d236 ("media: uapi: h264: Rename and clarify PPS_FLAG_SCALING_MATRIX_PRESENT") > Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c index 76e919b71a35..b950675b1db1 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c @@ -114,6 +114,7 @@ static void std_init_compound(const struct v4l2_ctrl *ctrl, u32 idx, struct v4l2_ctrl_vp8_frame *p_vp8_frame; struct v4l2_ctrl_vp9_frame *p_vp9_frame; struct v4l2_ctrl_fwht_params *p_fwht_params; + struct v4l2_ctrl_h264_scaling_matrix *p_h264_scaling_matrix; void *p = ptr.p + idx * ctrl->elem_size; if (ctrl->p_def.p_const) @@ -168,6 +169,15 @@ static void std_init_compound(const struct v4l2_ctrl *ctrl, u32 idx, p_fwht_params->flags = V4L2_FWHT_FL_PIXENC_YUV | (2 << V4L2_FWHT_FL_COMPONENTS_NUM_OFFSET); break; + case V4L2_CTRL_TYPE_H264_SCALING_MATRIX: + p_h264_scaling_matrix = p; + /* + * The default (flat) H.264 scaling matrix when none are + * specified in the bitstream, this is according to formulas + * (7-8) and (7-9) of the specification. + */ + memset(p_h264_scaling_matrix, 16, sizeof(*p_h264_scaling_matrix)); + break; } }
In the final H264 API, it is not required to set scaling matrix if they are not present in the bitstream. A flag was added in order to let the driver know. The downside is that it leaves the default control value to 0, which isn't valid. As per the spec (see formulas 7-8/7-9), when the scaling matrix are absent from the bitstream, flat values of 16 should be used. This improves this control semantic in a way that the control value are always valid. Drivers can then use the scaling_matrix control values without having to check its presence. Same method was employed for MPEG2_QUANTISATION. This fixes issues with MTK VCODEC H264 decoder when using GStreamer. GStreamer does not set this control if its not present in the bitstream. As MTK VDCODEC was using the initialized to 0 values, the frames ended up completely gray. Fixes: 54889c51b833d236 ("media: uapi: h264: Rename and clarify PPS_FLAG_SCALING_MATRIX_PRESENT") Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> --- drivers/media/v4l2-core/v4l2-ctrls-core.c | 10 ++++++++++ 1 file changed, 10 insertions(+)