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

[Aman Karmani <ffmpeg@tmm1.net>]

On Sat, Nov 19, 2022 at 6:56 AM Zhao Zhili <quinkblack@foxmail.com> wrote:

> 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@foxmail.com>
> > wrote:
> > > From: Zhao Zhili <zhilizhao@tencent.com>
> > >
> > > The crop info is optional, but used unconditionally.
> > >
> > > Signed-off-by: Zhao Zhili <zhilizhao@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.


Ah, yes I remember now. When I tried it, there was no way to access crop
information. I filed this bug:
https://issuetracker.google.com/issues/111262883?pli=1


>
>
> 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.


I checked this more and it seems to be specific to NVIDIA Shield. In that
encoder there is also a non-standard way to request scaling before encode,
so perhaps they added crop-{height,width} for scaling purposes as well.

For reference you can find libavcodec/mediacodecndkdec.c inside
https://downloads.plex.tv/ffmpeg-source/plex-media-server-ffmpeg-gpl-2427c1679fd.tar.gz


>
> >
>
>
>
>
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