On Sun, Dec 18, 2016 at 9:52 PM, wm4 <nfx...@googlemail.com> wrote:
> 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.
By using technically invalid dimensions and hoping chroma dimensions
are rounded up - its anything but clean.
I would rather have a full cropping rect and have a clean way to
communicate this, with w/h (optionally) unmolested.
- Hendrik
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