[FFmpeg-devel] [PATCH 01/12] avcodec/mediacodec: fix incorrect crop info

[Zhao Zhili]

On Sat, 2022-11-19 at 00:20 -0800, Aman Karmani wrote:
> Thank you for your work on this patchset!
> 
> On Sun, Oct 23, 2022 at 8:17 PM Zhao Zhili <quinkblack at foxmail.com>
> wrote:
> > From: Zhao Zhili <zhilizhao at tencent.com>
> > 
> > The crop info is optional, but used unconditionally.
> > 
> > Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
> > ---
> >  libavcodec/mediacodecdec_common.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/libavcodec/mediacodecdec_common.c
> > b/libavcodec/mediacodecdec_common.c
> > index 2a605e7f5b..c1cbb28488 100644
> > --- a/libavcodec/mediacodecdec_common.c
> > +++ b/libavcodec/mediacodecdec_common.c
> > @@ -487,6 +487,11 @@ static int
> > mediacodec_dec_parse_format(AVCodecContext *avctx,
> > MediaCodecDecConte
> >      AMEDIAFORMAT_GET_INT32(s->crop_left,   "crop-left",   0);
> >      AMEDIAFORMAT_GET_INT32(s->crop_right,  "crop-right",  0);
> > 
> > +    if (s->crop_bottom == 0 || s->crop_right == 0) {
> > +        s->crop_top = s->crop_left = 0;
> > +        s->crop_right = s->width - 1;
> > +        s->crop_bottom = s->height - 1;
> > +    }
> >      width = s->crop_right + 1 - s->crop_left;
> >      height = s->crop_bottom + 1 - s->crop_top;
> 
> I had another approach I have been using for some time. WDYT?
> 
> http://github.com/tmm1/ffmpeg/commit/ebc0ef75d25e712278c34427ef2f7d42f3dcf883

I found the issue when testing NDK mediacodec. There is no 'crop-left',
'crop-right' and so on. However, there is a 'crop' field in AMediaForma
t, for example:

android._video-scaling: int32(1), crop: Rect(0, 0, 1919, 1079), color-
standard: int32(1), ...

Unfortunately, it's available only since API level 28:

------------------------------------------------
extern const char* AMEDIAFORMAT_KEY_DISPLAY_CROP __INTRODUCED_IN(28);

/**
 * Available since API level 28.
 */
bool AMediaFormat_getRect(AMediaFormat*, const char *name,
        int32_t *left, int32_t *top, int32_t *right, int32_t *bottom)
__INTRODUCED_IN(28);
-------------------------------------------------

So we need to add a new API in mediacodec_wrapper first, then extract
crop info. It's on my TODO list.


For your patch,

+        AMEDIAFORMAT_GET_INT32(width,  "crop-width",  0);
+        AMEDIAFORMAT_GET_INT32(height, "crop-height", 0);

I can't find documention about these fields, and they didn't show on
Google Pixel 3. What's the device model? We can use it as a fallback,
after crop-left/crop-right and crop rect failed.

>