linux-kernel - Re: Re: Re: [PATCH v6 16/17] media: uapi: Change data_bit

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Message-ID: <3180718.44csPzL39Z@kista>
Date:   Mon, 13 Jun 2022 20:17:27 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     mchehab@...nel.org, hverkuil@...all.nl,
        ezequiel@...guardiasur.com.ar, p.zabel@...gutronix.de,
        gregkh@...uxfoundation.org, mripard@...nel.org,
        paul.kocialkowski@...tlin.com, wens@...e.org, samuel@...lland.org,
        nicolas.dufresne@...labora.com, andrzej.p@...labora.com,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        kernel@...labora.com
Subject: Re: Re: Re: [PATCH v6 16/17] media: uapi: Change data_bit_offset definition

Dne nedelja, 12. junij 2022 ob 22:40:29 CEST je Jernej Škrabec napisal(a):
> 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@...labora.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...

Further testing showed that I make a mistake in ffmpeg code. uAPI and suggested 
changes are fine. It's gtg.

Sorry for the false alarm!
 
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
> > >>>
> > >>>
> > >>
> > >>
> > >
> > 
> 
> 
>