Re: [FFmpeg-devel] [PATCH v7 09/10] qsv: use a new method to create mfx session when using oneVPL

[Hendrik Leppkes <h.leppkes@gmail.com>]

On Tue, Mar 15, 2022 at 8:24 AM Xiang, Haihao
<haihao.xiang-at-intel.com@ffmpeg.org> wrote:
>
> On Fri, 2022-03-11 at 15:00 +0100, Hendrik Leppkes wrote:
> > On Fri, Mar 11, 2022 at 2:43 PM Xiang, Haihao
> > <haihao.xiang-at-intel.com@ffmpeg.org> wrote:
> > >
> > > On Fri, 2022-03-11 at 09:35 +0100, Hendrik Leppkes wrote:
> > > > On Fri, Mar 11, 2022 at 9:18 AM Xiang, Haihao
> > > > <haihao.xiang-at-intel.com@ffmpeg.org> wrote:
> > > > > diff --git a/libavutil/hwcontext_d3d11va.c
> > > > > b/libavutil/hwcontext_d3d11va.c
> > > > > index 8ab96bad25..e0e820f164 100644
> > > > > --- a/libavutil/hwcontext_d3d11va.c
> > > > > +++ b/libavutil/hwcontext_d3d11va.c
> > > > > @@ -525,6 +525,13 @@ static void d3d11va_device_uninit(AVHWDeviceContext
> > > > > *hwdev)
> > > > >      }
> > > > >  }
> > > > >
> > > > > +static void d3d11va_device_free(AVHWDeviceContext *ctx)
> > > > > +{
> > > > > +    AVD3D11VADeviceContext *hwctx = ctx->hwctx;
> > > > > +
> > > > > +    av_free(hwctx->device_name);
> > > > > +}
> > > > > +
> > > > >  static int d3d11va_device_create(AVHWDeviceContext *ctx, const char
> > > > > *device,
> > > > >                                   AVDictionary *opts, int flags)
> > > > >  {
> > > > > @@ -537,6 +544,8 @@ static int d3d11va_device_create(AVHWDeviceContext
> > > > > *ctx,
> > > > > const char *device,
> > > > >      int is_debug       = !!av_dict_get(opts, "debug", NULL, 0);
> > > > >      int ret;
> > > > >
> > > > > +    ctx->free = d3d11va_device_free;
> > > > > +
> > > > >      // (On UWP we can't check this.)
> > > > >  #if !HAVE_UWP
> > > > >      if (!LoadLibrary("d3d11_1sdklayers.dll"))
> > > > > @@ -561,6 +570,10 @@ static int d3d11va_device_create(AVHWDeviceContext
> > > > > *ctx, const char *device,
> > > > >              if (FAILED(IDXGIFactory2_EnumAdapters(pDXGIFactory,
> > > > > adapter,
> > > > > &pAdapter)))
> > > > >                  pAdapter = NULL;
> > > > >              IDXGIFactory2_Release(pDXGIFactory);
> > > > > +
> > > > > +            device_hwctx->device_name = av_strdup(device);
> > > > > +            if (!device_hwctx->device_name)
> > > > > +                return AVERROR(ENOMEM);
> > > > >          }
> > > > >      }
> > > > >
> > > > > diff --git a/libavutil/hwcontext_d3d11va.h
> > > > > b/libavutil/hwcontext_d3d11va.h
> > > > > index 77d2d72f1b..41a315b9e6 100644
> > > > > --- a/libavutil/hwcontext_d3d11va.h
> > > > > +++ b/libavutil/hwcontext_d3d11va.h
> > > > > @@ -94,6 +94,11 @@ typedef struct AVD3D11VADeviceContext {
> > > > >      void (*lock)(void *lock_ctx);
> > > > >      void (*unlock)(void *lock_ctx);
> > > > >      void *lock_ctx;
> > > > > +
> > > > > +    /**
> > > > > +     * The string for the used adapter
> > > > > +     */
> > > > > +    char *device_name;
> > > > >  } AVD3D11VADeviceContext;
> > > > >
> > > > >  /**
> > > > > diff --git a/libavutil/hwcontext_dxva2.c b/libavutil/hwcontext_dxva2.c
> > > > > index 53d00fa815..6967357093 100644
> > > > > --- a/libavutil/hwcontext_dxva2.c
> > > > > +++ b/libavutil/hwcontext_dxva2.c
> > > > > @@ -431,6 +431,7 @@ static void dxva2_device_free(AVHWDeviceContext
> > > > > *ctx)
> > > > >          dlclose(priv->dxva2lib);
> > > > >
> > > > >      av_freep(&ctx->user_opaque);
> > > > > +    av_free(hwctx->device_name);
> > > > >  }
> > > > >
> > > > >  static int dxva2_device_create9(AVHWDeviceContext *ctx, UINT adapter)
> > > > > @@ -571,6 +572,13 @@ static int dxva2_device_create(AVHWDeviceContext
> > > > > *ctx,
> > > > > const char *device,
> > > > >          return AVERROR_UNKNOWN;
> > > > >      }
> > > > >
> > > > > +    if (device) {
> > > > > +        hwctx->device_name = av_strdup(device);
> > > > > +
> > > > > +        if (!hwctx->device_name)
> > > > > +            return AVERROR(ENOMEM);
> > > > > +    }
> > > > > +
> > > > >      return 0;
> > > > >  }
> > > > >
> > > > > diff --git a/libavutil/hwcontext_dxva2.h b/libavutil/hwcontext_dxva2.h
> > > > > index e1b79bc0de..253ddbed51 100644
> > > > > --- a/libavutil/hwcontext_dxva2.h
> > > > > +++ b/libavutil/hwcontext_dxva2.h
> > > > > @@ -38,6 +38,10 @@
> > > > >   */
> > > > >  typedef struct AVDXVA2DeviceContext {
> > > > >      IDirect3DDeviceManager9 *devmgr;
> > > > > +    /**
> > > > > +     * The string for the used adapter
> > > > > +     */
> > > > > +    char *device_name;
> > > > >  } AVDXVA2DeviceContext;
> > > > >
> > > > >  /**
> > > >
> > > > Why are these device names required? I would think deriving a child
> > > > device would use the actual device, eg. ID3D11Device or
> > > > IDirect3DDeviceManager9 (and whatever for VAAPI), and not some string
> > > > (that may or may not even be set).
> > > > It feels quite a bit icky to store these in the context just for qsv
> > > > to do... what with?
> > >
> > > Yes, it is a little ugly here. MediaSDK or oneVPL application creates mfx
> > > session and the device (dxva2, d3d11va or vaapi), then pass this device to
> > > the
> > > SDK through MFXVideoCORE_SetHandle(). implementation is introduced in oneVPL
> > > (
> > >
> https://spec.oneapi.io/versions/latest/elements/oneVPL/source/API_ref/VPL_disp_api_struct.html#structmfx_impl_description
> > > ) and user must select an available implementation before the creation of
> > > mfx
> > > session, however the device handle is unknown in the SDK when selecting an
> > > available implementation, the SDK provides a method to select implementation
> > > via
> > > the given adapter (on Windows) or DRI device node (on Linux). The default
> > > implementation will be selected if child device name is unknown.
> > >
> >
> > First of all, whoever made that API should get a stern message.
> > Expecting to properly interoperate with the dominant platform APIs
> > should be a primary goal, and it sounds like it was somehow shoehorned
> > in after the fact.
> >
> > For D3D11 for example, you can get the IDXGIAdapter a device was
> > created from, isn't there enough information in there to pass-on
> > without storing a string field?
> > IDXGIAdapter::GetDesc has tons of identification information to
> > identify the device in use.
> >
> > D3D9 probably has something similar, haven't checked right now.
>
>
> Thanks for the info, I may get AdapterLuid from the adapter description, however
> the required parameter in oneVPL is the index of the adapter, is there a way to
> map AdapterLuid to adapter index ? (Sorry for this dumb question)
>
> There is `IDirect3DDeviceManager9 *devmgr` only in AVDXVA2DeviceContext for
> D3D9, it seems we have to add other members to get adapter description.
>
> As for vaapi, there is no API to get the used DRI device from VADisplay handle,
> we have to store this info in AVVAAPIDeviceContext, and I prefer using the same
> way for d3d9 & d3d11va too.
>

I'm not sure about VAAPI, but not storing a string just for this one
purpose seems like a win to me.
What values would
mfxImplDescription.mfxDeviceDescription.device.DeviceID contain, and
would that perhaps match something in the D3D11 or DXVA2 device
description?

You already have big alternate pathes inside those functions for
windows or vaapi, so that doesn't seem like a big step to handle
separately.

- Hendrik
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