On Wed, Nov 30, 2016 at 02:18:36PM +0100, wm4 wrote: > On Wed, 30 Nov 2016 11:08:10 +0000 > Mark Thompson <s...@jkqxz.net> wrote: > > > On 30/11/16 02:20, Jun Zhao wrote: > > > From 20bedd18213420c77d5e8a26fbe741d8d204ac10 Mon Sep 17 00:00:00 2001 > > > From: Jun Zhao <jun.z...@intel.com> > > > Date: Tue, 29 Nov 2016 14:14:25 +0800 > > > Subject: [PATCH] lavc/vaapi_h26[45]: add crop info support in > > > vaapi_h26[4,5] > > > > > > add crop information support in vaapi_h26[4,5] hwaccel decode, > > > and align h264/hevc software decoder. After this fix, FATE test > > > h264-conformance-cvfc1_sony_c/hevc-conformance-CONFWIN_A_Sony_1 > > > will pass in i965/SKL. > > > > > > Signed-off-by: Wang, Yi A <yi.a.w...@intel.com> > > > Signed-off-by: Jun Zhao <jun.z...@intel.com> > > > --- > > > libavcodec/h264dec.c | 13 +++++++++++++ > > > libavcodec/hevc_refs.c | 7 +++++++ > > > libavutil/hwcontext.h | 6 ++++++ > > > libavutil/hwcontext_vaapi.c | 1 + > > > 4 files changed, 27 insertions(+) > > > > No. Top/left cropping needs a more general approach, not hacks in specific > > decoders/hwcontexts. > > > > Among other things: > > - The hardware frame context is owned by the user, you can't edit it like > > this from inside the decoder. > > - It can't be per-frame-context anyway, because multiple streams can be > > decoded into the same frame context. > > - More components need to be aware of it: the scale filters definitely > > should be (at > > <https://git.libav.org/?p=libav.git;a=blob;f=libavfilter/vf_scale_vaapi.c;h=50be68eee07374a78bba1eed8850c3ab9e019fe6;hb=HEAD#l291>, > > in VAAPI, similarly for the other hardware APIs). Other components can > > probably ignore it (with docs saying you should put it through the relevant > > scale filter if you want correctly-cropped images), but we should make that > > decision explicitly. > > - Messing with pointers/sizes on frame upload/download has issues with APIs > > which can only transfer whole frames - see the comment at > > <http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavutil/hwcontext.h;h=785da090b3fc4b4e91f989370ea4606c79bae823;hb=HEAD#l321>. > > (That was written with VDPAU in mind, there are likely others.) > > > > As wm4 notes in another reply, this ends up pointing to some sort of > > cropping information associated with the AVFrame which all interested > > components can then read. > > > > I know several people have expressed interest in this problem: given that, > > it's probably a good idea to have some discussion first and decide roughly > > what the result should look like before writing a lot of code for it. > > I've always argued for having a cropping rectangle directly in AVFrame, > but the idea was never popular.
AVFrame had a pan_scan parameter to store one or more croping rectangles. That is now available as side data I remember the intend that this could be used for multiple rectangles of different sizes for example for storing recommanded display rectangles for a 4:3 and a 16:9 display device, but it seems only a single size per frame is supported in the API [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Freedom in capitalist society always remains about the same as it was in ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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