Quoting Vittorio Giovara (2016-12-19 10:11:29)
> 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;
> > } AVFrame;
>
> I have a couple of points about this, in random order:
>
> 1. I had thought agreement was more towards a side data type rather
> than full types, is there any advantage with this approach?
CertainPeople(tm) claim that this is such an essential information about
the frame that it should live directly in it. I do not have a strong
opinion on the matter, so whatever is least objectionable to most people
is fine with me.
> 2. I would agree about having a full rectangle not two directions
> only. Possibly I would keep naming consistent with coded_width and
> coded_height as fields for uncropped size, and width and height for
> cropped size. Optionally left and top could be marked as offset.
Others seems to prefer that width/height are the pure original coded
values, with a full cropping rectangle.
> 3. What about container cropping? eg mov
The caller's job.
> 4. Does this support unaligned cropping? If not what happens to the
> options about it?
Read the following patches to find out.
> 5. What about Theora?
What about it?
> 6. Regarding 2/4, can you add a "third" way for apply_cropping so that
> it exports uncropped values but automatically adds the crop filter
> (kinda like we do for autorotate) and returns the filtered image at
> the cropped dimensions?
avcodec is unable to add any filters. If you wanted to call lavfi from
lavc, j-b would personally strangle you.
--
Anton Khirnov
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