[FFmpeg-devel] [PATCH v5 2/2] lavc/vaapi_decode: add support for HWACCEL_CAP_RESET_WITHOUT_UNINIT

Wang, Fei W fei.w.wang at intel.com
Thu Dec 1 03:55:25 EET 2022


On Mon, 2022-11-28 at 13:20 +0000, Mark Thompson wrote:
> On 14/11/2022 01:16, Fei Wang wrote:
> > This can fix vp9 decode image corruption when the frame size is
> > change,
> > but the pervious frames still be referenced.
> > 
> > Surfaces don't need to be bound to vaContext only after VAAPI
> > 1.0.0:
> > https://github.com/intel/libva/commit/492b692005ccd0d8da190209d5b3ae7b7825f4b8
> > 
> > Signed-off-by: Fei Wang <fei.w.wang at intel.com>
> > ---
> >   libavcodec/vaapi_decode.c | 11 ++++++++---
> >   libavcodec/vaapi_decode.h |  1 +
> >   libavcodec/vaapi_vp9.c    |  4 ++++
> >   3 files changed, 13 insertions(+), 3 deletions(-)
> 
> This always segfaults immediately on anything unsupported.  E.g. with
> fate/hevc/paramchange_yuv420p_yuv420p10.hevc:
> 
> [hevc @ 0x555557c0e7c0] Format vaapi chosen by get_format().
> [hevc @ 0x555557c0e7c0] Format vaapi requires hwaccel initialisation.
> [hevc @ 0x555557c0e7c0] Hardware does not support image size
> 1056x8440 (constraints: width 0-4096 height 0-4096).
> 
> Thread 20 "av:hevc:df0" received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7fffb4ff9700 (LWP 509456)]
> ff_vaapi_decode_uninit (avctx=0x555557c0e7c0) at
> src/libavcodec/vaapi_decode.c:714
> 714             vas = vaDestroyContext(ctx->hwctx->display, ctx-
> >va_context);
> (gdb) bt
> #0  ff_vaapi_decode_uninit (avctx=0x555557c0e7c0) at
> src/libavcodec/vaapi_decode.c:714
> #1  0x00005555563073d7 in ff_vaapi_decode_init (avctx=0x555557c0e7c0)
> at src/libavcodec/vaapi_decode.c:704
> #2  0x0000555555e62fee in hwaccel_init (avctx=0x555557c0e7c0,
> hw_config=0x55555728f770 <__compound_literal.0>) at
> src/libavcodec/decode.c:1121
> #3  0x0000555555e634ec in ff_get_format (avctx=0x555557c0e7c0,
> fmt=0x7fffb4ff8ccc) at src/libavcodec/decode.c:1261
> #4  0x00005555561ca829 in ff_thread_get_format (avctx=0x555557c0e7c0,
> fmt=0x7fffb4ff8ccc) at src/libavcodec/pthread_frame.c:1048
> #5  0x0000555555f68f37 in get_format (s=0x555557c3e6c0,
> sps=0x555557c21f80) at src/libavcodec/hevcdec.c:505
> #6  0x0000555555f69621 in hls_slice_header (s=0x555557c3e6c0) at
> src/libavcodec/hevcdec.c:618
> #7  0x0000555555f7472d in decode_nal_unit (s=0x555557c3e6c0,
> nal=0x7fff8802e920) at src/libavcodec/hevcdec.c:3173
> #8  0x0000555555f7508a in decode_nal_units (s=0x555557c3e6c0,
> buf=0x7ffff637c010 "", length=159280) at
> src/libavcodec/hevcdec.c:3355
> #9  0x0000555555f756d6 in hevc_decode_frame (avctx=0x555557c0e7c0,
> rframe=0x555557c0ecc0, got_output=0x555557c0d690,
> avpkt=0x555557c0ef40) at src/libavcodec/hevcdec.c:3497
> #10 0x00005555561c839c in frame_worker_thread (arg=0x555557c0d580) at
> src/libavcodec/pthread_frame.c:241
> #11 0x00007ffff68ccea7 in start_thread (arg=<optimized out>) at
> pthread_create.c:477
> #12 0x00007ffff67ecaef in clone () at
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
> (gdb)

Thanks, will fix this in next version.

> 
> 
> Also, I don't see how this is testing whether the driver supports
> changing the resolution at runtime?  The note in libva that you cite
> allows new switching render targets in the context, but I don't see
> why different resolution would be allowed given that it's a parameter
> passed to vaCreateContext()?
> 
> Looking at the Mesa driver it appears that the internally-allocated
> references are not going to allow size changes (where does the
> template width get updated?).  I don't have any hardware to test
> that, though - are you able to try this on recent AMD hardware with
> VP9 support?

I checked on AMD RX6700XT, it can get correct output when decoding
multi-resolution vp9 clips only after apply this patchset. For example,
by using clip from:
https://storage.googleapis.com/downloads.webmproject.org/vp9/decoder-test-streams/Profile_0_8bit.zip

VP9 native decode result:
ffmpeg -i
Profile_0_8bit/frm_resize/crowd_run_1080X512_fr30_bd8_frm_resize_l3.web
m -pix_fmt yuv420p -autoscale 0 -f md5 -y -
[...]
MD5=51b3393fa98ad9ab99c0b45ef705ebc4
[...]

Without this patchset:
ffmpeg -v verbose -hwaccel vaapi -i
Profile_0_8bit/frm_resize/crowd_run_1080X512_fr30_bd8_frm_resize_l3.web
m -pix_fmt yuv420p -autoscale 0 -f md5 -y -
[...]
[AVHWDeviceContext @ 0x56526336a000] VAAPI driver: Mesa Gallium driver
22.3.0-rc4 for AMD Radeon RX 6700 XT (navi22, LLVM 11.0.0, DRM 3.44,
5.13.0-40-generic).
[...]
MD5=2e799f0f916195f86a356907f7e4eae1 (change from time to time, but
never same with native decode result)
[...]

With this patchset:
ffmpeg -v verbose -hwaccel vaapi -i
Profile_0_8bit/frm_resize/crowd_run_1080X512_fr30_bd8_frm_resize_l3.web
m -pix_fmt yuv420p -autoscale 0 -f md5 -y -
[...]
[AVHWDeviceContext @ 0x561c08e7a000] VAAPI driver: Mesa Gallium driver
22.3.0-rc4 for AMD Radeon RX 6700 XT (navi22, LLVM 11.0.0, DRM 3.44,
5.13.0-40-generic).
[...]
MD5=51b3393fa98ad9ab99c0b45ef705ebc4
[...]

That means both Intel and AMD driver implementation doesn't limit
surface's resolution must be same with vacontext. So I think we can add
some description to libva to declare that.

> 
> What have you done to verify the METHOD_HW_FRAMES_CTX
> behaviour?  This has changed so that vaapi_decode_make_config() is no
> longer called, which feels possibly-bad though I'm unsure of the
> exact consequences.
> 
> As I said last time, I do think you should only do this in exactly
> the places where it is required, and not change any other behaviour.

vaapi_decode_make_config() is called by ff_decode_get_hw_frames_ctx()
in ff_vaapi_decode_init. So the change to vaapi_decode_make_config
doesn't impact the final result.
To avoid confusion, I will not change its behaviour in next version.

Thanks
Fei

> 
> Thanks,
> 
> - Mark
> 
> > diff --git a/libavcodec/vaapi_decode.c b/libavcodec/vaapi_decode.c
> > index 134f10eca5..d950471b6d 100644
> > --- a/libavcodec/vaapi_decode.c
> > +++ b/libavcodec/vaapi_decode.c
> > @@ -658,9 +658,6 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
> >       VAStatus vas;
> >       int err;
> >   
> > -    ctx->va_config  = VA_INVALID_ID;
> > -    ctx->va_context = VA_INVALID_ID;
> > -
> >       err = ff_decode_get_hw_frames_ctx(avctx,
> > AV_HWDEVICE_TYPE_VAAPI);
> >       if (err < 0)
> >           goto fail;
> > @@ -670,6 +667,12 @@ int ff_vaapi_decode_init(AVCodecContext
> > *avctx)
> >       ctx->device = ctx->frames->device_ctx;
> >       ctx->hwctx  = ctx->device->hwctx;
> >   
> > +    if (ctx->inited)
> > +        return 0;
> > +
> > +    ctx->va_config  = VA_INVALID_ID;
> > +    ctx->va_context = VA_INVALID_ID;
> > +
> >       err = vaapi_decode_make_config(avctx, ctx->frames-
> > >device_ref,
> >                                      &ctx->va_config, NULL);
> >       if (err)
> > @@ -691,6 +694,8 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
> >       av_log(avctx, AV_LOG_DEBUG, "Decode context initialised: "
> >              "%#x/%#x.\n", ctx->va_config, ctx->va_context);
> >   
> > +    ctx->inited = 1;
> > +
> >       return 0;
> >   
> >   fail:
> > diff --git a/libavcodec/vaapi_decode.h b/libavcodec/vaapi_decode.h
> > index 6beda14e52..62a4f37ed9 100644
> > --- a/libavcodec/vaapi_decode.h
> > +++ b/libavcodec/vaapi_decode.h
> > @@ -61,6 +61,7 @@ typedef struct VAAPIDecodeContext {
> >       int                   surface_count;
> >   
> >       VASurfaceAttrib       pixel_format_attribute;
> > +    int                   inited;
> >   } VAAPIDecodeContext;
> >   
> >   
> > diff --git a/libavcodec/vaapi_vp9.c b/libavcodec/vaapi_vp9.c
> > index 776382f683..245b7a1b3a 100644
> > --- a/libavcodec/vaapi_vp9.c
> > +++ b/libavcodec/vaapi_vp9.c
> > @@ -181,5 +181,9 @@ const AVHWAccel ff_vp9_vaapi_hwaccel = {
> >       .uninit               = ff_vaapi_decode_uninit,
> >       .frame_params         = ff_vaapi_common_frame_params,
> >       .priv_data_size       = sizeof(VAAPIDecodeContext),
> > +#if VA_CHECK_VERSION(1, 0, 0)
> > +    .caps_internal        = HWACCEL_CAP_ASYNC_SAFE |
> > HWACCEL_CAP_RESET_WITHOUT_UNINIT,
> > +#else
> >       .caps_internal        = HWACCEL_CAP_ASYNC_SAFE,
> > +#endif
> >   };
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