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Date: Sat, 14 Sep 2013 05:22:41 +0200
From: Hans Verkuil <hverkuil@xs4all.nl>
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To: vkalia@codeaurora.org
CC: linux-media@vger.kernel.org
Subject: Re: User data propagation for video codecs
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On 09/13/2013 11:54 PM, vkalia@codeaurora.org wrote:
> Hi
>
> For video decoder, our video driver, which is V4l2 based, exposes two
> capabilities:
>
> 1. V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE for transaction of compressed buffers.
> 2. V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE for transaction of
> decoded/uncompressed buffers.
>
> We have a requirement to propagate "user specific data" from compressed
> buffer to uncompressed buffer. We are not able to find any field in
> "struct v4l2_buffer" which can be used for this purpose. Please suggest if
> this can be achieved with current V4L2 framework.

It depends how the user data is organized. If it is situated right
before the actual data, then the data_offset field of v4l2_plane can be
used. If it is an independent piece of data, then you can pass it on in
an additional plane.

Regards,

    Hans