[Libav-user] libavcodec/av1dec.c - Changing the tile data submitted for HW Acceleration

[Veerabadhran Gopalakrishnan]

Fei,
Thank you for your response.
I am looking at adding my own header which I'm planning to parse in mesa
driver.
To be exact, I would like to add my header after the default frame headers
in the unit->data at the av1_decode_frame() function.
I tried allocating my own buffer bigger than the
"raw_tile_group->tile_data.data" and added my header in front of the
actual data.  I'm afraid the cleanup will miss my buffer and lead to leak.
I have two questions
1. How can I get the frame header size?
    I see the frame header size is available from CodedBitstreamAV1Context
in the libavcodec/cbs_av1_syntax_template.c:frame_header_obu().  Please let
me know how to get it in the AV1DecContext in the av1dec.c.
2. How to realloc the "raw_tile_group->tile_data.data" to insert my buffer
inbetween.
Let's say the current buffer sent to hw_decode is (FrameHeader+FrameData),
the modified buffer will look like (FrameHeader+MyOwnHeader+FrameData).

The other codecs hevc and vp9 were using "AVPacket" for the slice data, I
added my header by a simple realloc of the AVPacket.  For AV1, I'm a bit
lost because of the tile data structures.

Thanks,
Veera

On Wed, Aug 17, 2022 at 7:28 PM Wang, Fei W <
fei.w.wang-at-intel.com at ffmpeg.org> wrote:

> On Wed, 2022-08-17 at 18:13 +0530, Veerabadhran Gopalakrishnan wrote:
>
> Hi,
> I would like to add an extra header in front of the tile data which is
> being passed to the decode_slice.
> Could you please recommend how to modify the buffers in a safer and leak
> proof way?
>
>
> What kind of extra header? If frame header or sequence header you can get
> from AVCodecContext inside decode_slice.
>
> Thanks
> Fei
>
>
>
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-- 
Thanks & Regards,
Veerabadhran G
Ph - 8553776883
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