[FFmpeg-devel] [PATCH] avutil/frame: document alignment and padding requirements

[Clément Bœsch]

On Sun, Mar 17, 2013 at 03:23:19AM +0100, Michael Niedermayer wrote:
> Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> ---
>  libavutil/frame.h |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 8fc5814..2330840 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -78,6 +78,11 @@ typedef struct AVFrame {
>      /**
>       * pointer to the picture/channel planes.
>       * This might be different from the first allocated byte
> +     *
> +     * Some decoders access areas outside 0,0 - width,height, please
> +     * see avcodec_align_dimensions2(). Some filters can read upto 16 bytes

up to

Also, what are the filters? filters from libavfilter? Or this can refer to
codec filters?

Isn't swscale outside libavfilter also doing such extra read?

On a side note, a macro would be best.

> +     * beyond the planes, if these filters are to be used, then 16 extra
> +     * bytes must be allocated.
>       */
>      uint8_t *data[AV_NUM_DATA_POINTERS];
>  
> @@ -87,6 +92,9 @@ typedef struct AVFrame {
>       *
>       * For audio, only linesize[0] may be set. For planar audio, each channel
>       * plane must be the same size.
> +     *
> +     * For video the linesizes should be multiplies of the CPUs alignment
> +     * preferrance. This is 16 or 32 for modern desktop CPUs

preference, missing trailing '.'

You said "should"; this isn't a requirement, right?

[...]

-- 
Clément B.
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