Re: Re: [PATCH v6 16/17] media: uapi: Change data_bit_offset definition

Jernej Škrabec
2022-06-12T20:40:33Z

Dne sreda, 01. junij 2022 ob 18:33:22 CEST je Benjamin Gaignard napisal(a):
>
> Le 01/06/2022 à 18:17, Jernej Škrabec a écrit :
> > Dne nedelja, 29. maj 2022 ob 08:45:57 CEST je Jernej Škrabec napisal(a):
> >> Dne petek, 27. maj 2022 ob 16:31:33 CEST je Benjamin Gaignard napisal(a):
> >>> 'F.7.3.6.1 General slice segment header syntax' section of HEVC
> >>> specification describes that a slice header always end aligned on
> >>> byte boundary, therefore we only need to provide the data offset in
bytes.
> >>>
> >>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> >>> ---
> >>> Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 4 ++--
> >>> drivers/staging/media/sunxi/cedrus/cedrus_h265.c | 2 +-
> >>> include/media/hevc-ctrls.h | 4 ++--
> >>> 3 files changed, 5 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/
> >> Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> >>> index 48a8825a001b..37079581c661 100644
> >>> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> >>> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> >>> @@ -3008,8 +3008,8 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> >>> - ``bit_size``
> >>> - Size (in bits) of the current slice data.
> >>> * - __u32
> >>> - - ``data_bit_offset``
> >>> - - Offset (in bits) to the video data in the current slice data.
> >>> + - ``data_byte_offset``
> >>> + - Offset (in bytes) to the video data in the current slice data.
> >>> * - __u32
> >>> - ``num_entry_point_offsets``
> >>> - Specifies the number of entry point offset syntax elements in
the
> >> slice header.
> >>> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/
> >> staging/media/sunxi/cedrus/cedrus_h265.c
> >>> index 411601975124..835454239f73 100644
> >>> --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> >>> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> >>> @@ -405,7 +405,7 @@ static void cedrus_h265_setup(struct cedrus_ctx
*ctx,
> >>> /* Initialize bitstream access. */
> >>> cedrus_write(dev, VE_DEC_H265_TRIGGER,
> >> VE_DEC_H265_TRIGGER_INIT_SWDEC);
> >>>
> >>> - cedrus_h265_skip_bits(dev, slice_params->data_bit_offset);
> >>> + cedrus_h265_skip_bits(dev, slice_params->data_byte_offset * 8);
> >> While it's true that actual data starts on 8-bit aligned address, Cedrus
for
> >> some reason needs offset which points at the end of the header, before
> >> alignment. There is very simple way to determine that, but unfortunately
> > this
> >> means reading source buffer.
> >>
> >> In short, above code won't work. I'll provide a fix.
> > Please include following fix http://ix.io/3Z8x otherwise Cedrus will fail
to
> > decode slice.

Fluster testing show that this patch isn't completely fine. I also have some
other issues, which need control values comparisons. It would be best, if you
can wait until I finish comparison. Old, hackish HEVC patches have high fluster
score whereas new, based on stable uAPI, has low and CPU also locks up...

Best regards,
Jernej

> >
> > Other than fix in previous e-mail and this one, code looks good and I'll be
> > able to add missing functionality to Cedrus without much trouble in follow
up
> > series.
>
> Thanks for the patch it will be in version 7.
>
> Regards,
> Benjamin
>
> >
> > Best regards,
> > Jernej
> >
> >>>
> >>> /* Bitstream parameters. */
> >>>
> >>> diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> >>> index 9abca1a75bd4..936ff693967b 100644
> >>> --- a/include/media/hevc-ctrls.h
> >>> +++ b/include/media/hevc-ctrls.h
> >>> @@ -312,7 +312,7 @@ struct v4l2_hevc_pred_weight_table {
> >>> * V4L2_CTRL_FLAG_DYNAMIC_ARRAY flag must be set when using it.
> >>> *
> >>> * @bit_size: size (in bits) of the current slice data
> >>> - * @data_bit_offset: offset (in bits) to the video data in the current
> > slice
> >> data
> >>> + * @data_byte_offset: offset (in bytes) to the video data in the current
> >> slice data
> >>> * @num_entry_point_offsets: specifies the number of entry point offset
> > syntax
> >>> * elements in the slice header.
> >>> * @nal_unit_type: specifies the coding type of the slice (B, P or I)
> >>> @@ -356,7 +356,7 @@ struct v4l2_hevc_pred_weight_table {
> >>> */
> >>> struct v4l2_ctrl_hevc_slice_params {
> >>> __u32 bit_size;
> >>> - __u32 data_bit_offset;
> >>> + __u32 data_byte_offset;
> >>> __u32 num_entry_point_offsets;
> >>> /* ISO/IEC 23008-2, ITU-T Rec. H.265: NAL unit header */
> >>> __u8 nal_unit_type;
> >>> --
> >>> 2.32.0
> >>>
> >>>
> >>
> >>
> >
>