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

[Benjamin Gaignard]

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@xxxxxxxxxxxxx>
> > > ---
> > >   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.
>
> 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