On Sun, 18 Dec 2016 21:37:44 +0100
Hendrik Leppkes <h.lepp...@gmail.com> wrote:
> On Sun, Dec 18, 2016 at 9:27 PM, Anton Khirnov <an...@khirnov.net> wrote:
> > ---
> > doc/APIchanges | 4 ++++
> > libavutil/frame.c | 2 ++
> > libavutil/frame.h | 14 ++++++++++++++
> > libavutil/version.h | 2 +-
> > 4 files changed, 21 insertions(+), 1 deletion(-)
> >
> > diff --git a/doc/APIchanges b/doc/APIchanges
> > index 7633c99..ca95308 100644
> > --- a/doc/APIchanges
> > +++ b/doc/APIchanges
> > @@ -13,6 +13,10 @@ libavutil: 2015-08-28
> >
> > API changes, most recent first:
> >
> > +2016-xx-xx - xxxxxxx - lavu 55.30.0 - frame.h
> > + Add AVFrame.crop_left/crop_top fields for attaching cropping information
> > to
> > + video frames.
> > +
> > 2016-xx-xx - xxxxxxx - lavc 57.29.0 - avcodec.h
> > Add AV_PKT_DATA_SPHERICAL packet side data to export AVSphericalMapping
> > information from containers.
> > diff --git a/libavutil/frame.c b/libavutil/frame.c
> > index 1c14f5f..935c281 100644
> > --- a/libavutil/frame.c
> > +++ b/libavutil/frame.c
> > @@ -390,6 +390,8 @@ int av_frame_copy_props(AVFrame *dst, const AVFrame
> > *src)
> > dst->key_frame = src->key_frame;
> > dst->pict_type = src->pict_type;
> > dst->sample_aspect_ratio = src->sample_aspect_ratio;
> > + dst->crop_left = src->crop_left;
> > + dst->crop_top = src->crop_top;
> > dst->pts = src->pts;
> > dst->repeat_pict = src->repeat_pict;
> > dst->interlaced_frame = src->interlaced_frame;
> > diff --git a/libavutil/frame.h b/libavutil/frame.h
> > index 4052199..744d8d2 100644
> > --- a/libavutil/frame.h
> > +++ b/libavutil/frame.h
> > @@ -25,6 +25,7 @@
> > #ifndef AVUTIL_FRAME_H
> > #define AVUTIL_FRAME_H
> >
> > +#include <stddef.h>
> > #include <stdint.h>
> >
> > #include "avutil.h"
> > @@ -369,6 +370,19 @@ typedef struct AVFrame {
> > * AVHWFramesContext describing the frame.
> > */
> > AVBufferRef *hw_frames_ctx;
> > +
> > + /**
> > + * Video frames only.
> > + * The number of pixels to discard from the left border of the frame to
> > + * obtain the part of the frame intended for presentation.
> > + */
> > + size_t crop_left;
> > + /**
> > + * Video frames only.
> > + * The number of pixels to discard from the top border of the frame to
> > + * obtain the part of the frame intended for presentation.
> > + */
> > + size_t crop_top;
>
> If you start exporting cropping info, it should imho be a full rect,
> so you can eg. export 1px crop for 4:2:0 formats and whatnot, and not
> be limited to one specific use-case.
> Also, then it should be put into a struct and not 4 individual values.
We already support odd cropping of 4:2:0 frames. Try decoding a jpg
with odd dimensions.
Personally, I'd really love if we had the real (uncropped) with and
height of the frame in here too, though. Indirectly, this is present if
the pixfmt is a hwaccel and a hw_frames_ctx is set (the ctx has the
hw surface size, i.e. it has the uncropped width and height).
So:
- I'm fine with the patch above
- I'd be finer with it if we could redefine AVFrame.width/height to be
uncropped, and add crop_width/crop_height
For the latter, we could also have a codec context flag to apply
old-style cropping for software decoding (i.e. add a possibly unaligned
offset to the data pointers), which would be set by default in order
not to break old API users.
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