[FFmpeg-devel] [PATCH] Optimization: support for libx264's mb_info

[Carotti, Elias]

Hi Stefano,
thanks for checking the patch.
Please find it attached in the required format.
Best,
Elias


On Mon, 2023-05-22 at 01:17 +0200, Stefano Sabatini wrote:
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> 
> On date Friday 2023-05-19 10:19:03 +0000, Carotti, Elias wrote:
> > 
> > Hi again,
> > I am sending this patch again (I had missed a check for NULL),
> > could
> > somebody please have a look at it?
> > 
> > It is mainly an optimization when the encoder knows in advance that
> > only portions of the whole frame changed and which areas actually
> > did.
> > 
> > The patch allows a user to pass down information to libx264
> > information
> > about which parts of a frame changed (with respect to the preceding
> > one) to be exploited as a hint for P_SKIP-ing macroblocks which
> > didn't
> > change.
> > This information is encoded in the mb_info field of the
> > x264_param_t
> > much like the quant_offsets which are already used for the
> > AV_FRAME_DATA_REGIONS_OF_INTEREST side information.
> 
> Please send a git format-patch (complete with commit log information)
> to simplify integration.
> 
> [...]
> > diff --git a/libavutil/mb_info.h b/libavutil/mb_info.h
> > new file mode 100644
> > index 0000000000..918cf167aa
> > --- /dev/null
> > +++ b/libavutil/mb_info.h
> > @@ -0,0 +1,46 @@
> [...]
> > +#ifndef AVUTIL_MB_INFO_H
> > +#define AVUTIL_MB_INFO_H
> > +
> > +#include <stddef.h>
> > +#include <stdint.h>
> > +#include "libavutil/avassert.h"
> > +#include "libavutil/frame.h"
> > +
> 
> > +typedef struct _AVMBInfoRect {
> 
> nit: strip the _ before the struct name
> 
> > +    uint32_t x, y;
> > +    uint32_t width, height;
> > +} AVMBInfoRect;
> > +
> > +/**
> > + * Allocate memory for a vector of AVMBInfoRect in the given
> > AVFrame
> > + * {@code frame} as AVFrameSideData of type AV_FRAME_DATA_MB_INFO.
> 
> > + * The side data contains a list of rectangles for the portions of
> > the frame
> > + * which changed from the last encoded one. The rest will be
> > hinted to be
> > + * P_SKIP-ped.  Portions of the rects which are not on macroblock
> > boundaries
> > + * are not handled as P_SKIPS.
> > + */
> 
> > +AVMBInfoRect *av_mb_info_create_side_data(AVFrame *frame,
> > +                                          AVMBInfoRect *rects,
> > +                                          size_t num_rects);
> 
> Probably this can be generalized with a flag defining the hinting
> type
> (you might want either to specify the constant or non-constant
> rects),
> in fact this data is pretty macro-block agnostic.
> 
> What about AVVideoHintInfo containing a hint (CONSTANT, VARIANT) and
> a
> list of rects?
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