User data propagation for video codecs

User data propagation for video codecs

[vkalia]

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.


Thanks
Vinay

Re: User data propagation for video codecs

[Hans Verkuil]

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