ID3D11VideoContext::DecoderBeginFrame method

Starts a decoding operation to decode a video frame.

Syntax

HRESULT DecoderBeginFrame(
  [in]       ID3D11VideoDecoder           *pDecoder,
  [in]       ID3D11VideoDecoderOutputView *pView,
  [in]       UINT                         ContentKeySize,
  [in] const void                         *pContentKey
);

Parameters

pDecoder [in]

A pointer to the ID3D11VideoDecoder interface. To get this pointer, call ID3D11VideoDevice::CreateVideoDecoder.

pView [in]

A pointer to the ID3D11VideoDecoderOutputView interface. This interface describes the resource that will receive the decoded frame. To get this pointer, call ID3D11VideoDevice::CreateVideoDecoderOutputView.

ContentKeySize [in]

The size of the content key that is specified in pContentKey. If pContentKey is NULL, set ContentKeySize to zero.

pContentKey [in]

An optional pointer to a content key that was used to encrypt the frame data. If no content key was used, set this parameter to NULL. If the caller provides a content key, the caller must use the session key to encrypt the content key.

Return value

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code. D3DERR_WASSTILLDRAWING or E_PENDING is returned if the harware is busy, in which case the decoder should try to make the call again.

Remarks

After this method is called, call ID3D11VideoContext::SubmitDecoderBuffers to perform decoding operations. When all decoding operations have been executed, call ID3D11VideoContext::DecoderEndFrame.

Each call to DecoderBeginFrame must have a matching call to DecoderEndFrame. In most cases you cannot nest DecoderBeginFrame calls, but some codecs, such as like VC-1, can have nested DecoderBeginFrame calls for special operations like post processing.

The following encryption scenarios are supported through the content key:

• The decoder can choose to not encrypt every frame, for example it may only encrypt the I frames and not encrypt the P/B frames. In these scenario, the decoder will specify pContentKey = NULL and ContentKeySize = 0 for those frames that it does not encrypt.
• The decoder can choose to encrypt the compressed buffers using the session key. In this scenario, the decoder will specify a content key containing all zeros.
• The decoder can choose to encrypt the compressed buffers using a separate content key. In this scenario, the decoder will ECB encrypt the content key using the session key and pass the encrypted content key.

Requirements

See also

ID3D11VideoContext