media/gpu/windows/d3d11_decryptor.cc - chromium/src - Git at Google

 // Copyright 2018 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "media/gpu/windows/d3d11_decryptor.h"

 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "media/base/decoder_buffer.h"

 namespace media {

 namespace {

 // "A buffer is defined as a single subresource."
 // https://msdn.microsoft.com/en-us/library/windows/desktop/ff476901(v=vs.85).aspx
 const UINT kSubresourceIndex = 0;
 const UINT kWaitIfGPUBusy = 0;

 // This value is somewhat arbitrary but is a multiple of 16 and 4K and is
 // equal to D3D11_REQ_TEXTURE2D_U_OR_V_DIMENSION. Since the buffers are cast
 // to ID3D11Texture2D, setting it as its size should make sense.
 const UINT kBufferSize = 16384;

 // Creates ID3D11Buffer using the values. Return true on success.
 bool CreateBuffer(ID3D11Device* device,
                   D3D11_USAGE usage,
                   UINT bind_flags,
                   UINT cpu_access,
                   ID3D11Buffer** out) {
   D3D11_BUFFER_DESC buf_desc = {};

   buf_desc.ByteWidth = kBufferSize;
   buf_desc.BindFlags = bind_flags;
   buf_desc.Usage = usage;
   buf_desc.CPUAccessFlags = cpu_access;

   HRESULT hresult = device->CreateBuffer(&buf_desc, nullptr, out);
   return SUCCEEDED(hresult);
 }

 // Copies |input| into |output|, the output buffer should be a staging buffer
 // that is CPU writable.
 bool CopyDataToBuffer(base::span<const uint8_t> input,
                       ID3D11DeviceContext* device_context,
                       ID3D11Buffer* output) {
   D3D11_BUFFER_DESC output_buffer_desc = {};
   output->GetDesc(&output_buffer_desc);

   if (output_buffer_desc.ByteWidth < input.size()) {
     DVLOG(1) << input.size() << " does not fit in "
              << output_buffer_desc.ByteWidth;
     return false;
   }

   D3D11_MAPPED_SUBRESOURCE map_resource = {};
   HRESULT hresult =
       device_context->Map(output, kSubresourceIndex, D3D11_MAP_WRITE,
                           kWaitIfGPUBusy, &map_resource);
   if (FAILED(hresult)) {
     DVLOG(3) << "Failed to map buffer for writing.";
     return false;
   }
   memcpy(map_resource.pData, input.data(), input.size_bytes());
   device_context->Unmap(output, kSubresourceIndex);
   return true;
 }

 // Copies |input| into |output|. The input buffer is should be a staging buffer
 // that is CPU readable.
 bool CopyDataOutFromBuffer(ID3D11Buffer* input,
                            size_t input_size,
                            ID3D11DeviceContext* device_context,
                            std::vector<uint8_t>* output) {
   D3D11_MAPPED_SUBRESOURCE map_resource = {};
   HRESULT hresult = device_context->Map(
       input, kSubresourceIndex, D3D11_MAP_READ, kWaitIfGPUBusy, &map_resource);
   if (FAILED(hresult)) {
     DVLOG(3) << "Failed to map buffer for reading.";
     return false;
   }
   output->resize(input_size);
   memcpy(output->data(), map_resource.pData, input_size);
   device_context->Unmap(input, kSubresourceIndex);
   return true;
 }

 D3D11_AES_CTR_IV StringIvToD3D11Iv(const std::string& iv) {
   D3D11_AES_CTR_IV d3d11_iv = {};
   DCHECK_LE(iv.size(), 16u);
   memcpy(&d3d11_iv, iv.data(), iv.size());
   return d3d11_iv;
 }

 // Returns true if the entire sample is encrypted.
 bool IsWholeSampleEncrypted(const DecryptConfig& decrypt_config,
                             size_t sample_size) {
   const auto& subsamples = decrypt_config.subsamples();
   if (subsamples.size() != 1)
     return false;

   return subsamples.front().clear_bytes == 0 &&
          subsamples.front().cypher_bytes == sample_size;
 }

 // Checks whether |device1| is the same component as |device2|.
 // Note that comparing COM pointers require using their IUnknowns.
 // https://docs.microsoft.com/en-us/windows/desktop/api/unknwn/nf-unknwn-iunknown-queryinterface(q_)
 bool SameDevices(Microsoft::WRL::ComPtr<ID3D11Device> device1,
                  Microsoft::WRL::ComPtr<ID3D11Device> device2) {
   // For the case where both are nullptrs, they aren't devices, so returning
   // false here.
   if (!device1 || !device2)
     return false;
   Microsoft::WRL::ComPtr<IUnknown> device1_iunknown;
   Microsoft::WRL::ComPtr<IUnknown> device2_iunknown;
   HRESULT hr = device1.CopyTo(device1_iunknown.ReleaseAndGetAddressOf());
   if (FAILED(hr))
     return false;
   hr = device2.CopyTo(device2_iunknown.ReleaseAndGetAddressOf());
   if (FAILED(hr))
     return false;
   return device1_iunknown == device2_iunknown;
 }

 // Returns a value that is bigger than or equal to |num| that is a
 // multiple of 16.
 // E.g. num = 15 returns 16, 17 returns 32.
 UINT To16Multiple(size_t num) {
   return ((num + 15) >> 4) << 4;
 }

 }  // namespace

 D3D11Decryptor::D3D11Decryptor(CdmProxyContext* cdm_proxy_context)
     : cdm_proxy_context_(cdm_proxy_context), weak_factory_(this) {
   DCHECK(cdm_proxy_context_);
 }

 D3D11Decryptor::~D3D11Decryptor() {}

 void D3D11Decryptor::RegisterNewKeyCB(StreamType stream_type,
                                       const NewKeyCB& new_key_cb) {
   // TODO(xhwang): Use RegisterNewKeyCB() on CdmContext, and remove
   // RegisterNewKeyCB from Decryptor interface.
   NOTREACHED();
 }

 void D3D11Decryptor::Decrypt(StreamType stream_type,
                              scoped_refptr<DecoderBuffer> encrypted,
                              const DecryptCB& decrypt_cb) {
   if (encrypted->end_of_stream()) {
     decrypt_cb.Run(kSuccess, encrypted);
     return;
   }

   const auto* decrypt_config = encrypted->decrypt_config();
   if (!decrypt_config) {
     // Not encrypted, nothing to do.
     decrypt_cb.Run(kSuccess, encrypted);
     return;
   }

   if (decrypt_config->HasPattern()) {
     DVLOG(3) << "Cannot handle pattern decryption.";
     decrypt_cb.Run(kError, nullptr);
     return;
   }

   auto context = cdm_proxy_context_->GetD3D11DecryptContext(
       CdmProxy::KeyType::kDecryptOnly, decrypt_config->key_id());
   if (!context) {
     decrypt_cb.Run(kNoKey, nullptr);
     return;
   }

   // Because DecryptionBlt() implementation checks whether the device, buffers,
   // and the crypto session are from the same device, the buffers have to be
   // recreated.
   if (!InitializeDecryptionBuffer(*context)) {
     decrypt_cb.Run(kError, nullptr);
     return;
   }

   std::vector<uint8_t> output;
   if (IsWholeSampleEncrypted(*encrypted->decrypt_config(),
                              encrypted->data_size())) {
     if (!CtrDecrypt(base::make_span(encrypted->data(), encrypted->data_size()),
                     encrypted->decrypt_config()->iv(), *context, &output)) {
       decrypt_cb.Run(kError, nullptr);
       return;
     }
   } else {
     if (!SubsampleCtrDecrypt(encrypted, *context, &output)) {
       decrypt_cb.Run(kError, nullptr);
       return;
     }
   }

   auto decoder_buffer = DecoderBuffer::CopyFrom(output.data(), output.size());
   decoder_buffer->set_timestamp(encrypted->timestamp());
   decoder_buffer->set_duration(encrypted->duration());
   decoder_buffer->set_is_key_frame(encrypted->is_key_frame());
   decoder_buffer->CopySideDataFrom(encrypted->side_data(),
                                    encrypted->side_data_size());
   decrypt_cb.Run(kSuccess, decoder_buffer);
 }

 void D3D11Decryptor::CancelDecrypt(StreamType stream_type) {
   // Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
 }

 void D3D11Decryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
                                             const DecoderInitCB& init_cb) {
   // D3D11Decryptor does not support audio decoding.
   init_cb.Run(false);
 }

 void D3D11Decryptor::InitializeVideoDecoder(const VideoDecoderConfig& config,
                                             const DecoderInitCB& init_cb) {
   // D3D11Decryptor does not support video decoding.
   init_cb.Run(false);
 }

 void D3D11Decryptor::DecryptAndDecodeAudio(
     scoped_refptr<DecoderBuffer> encrypted,
     const AudioDecodeCB& audio_decode_cb) {
   NOTREACHED() << "D3D11Decryptor does not support audio decoding";
 }

 void D3D11Decryptor::DecryptAndDecodeVideo(
     scoped_refptr<DecoderBuffer> encrypted,
     const VideoDecodeCB& video_decode_cb) {
   NOTREACHED() << "D3D11Decryptor does not support video decoding";
 }

 void D3D11Decryptor::ResetDecoder(StreamType stream_type) {
   NOTREACHED() << "D3D11Decryptor does not support audio/video decoding";
 }

 void D3D11Decryptor::DeinitializeDecoder(StreamType stream_type) {
   // D3D11Decryptor does not support audio/video decoding, but since this can be
   // called any time after InitializeAudioDecoder/InitializeVideoDecoder,
   // nothing to be done here.
 }

 bool D3D11Decryptor::InitializeDecryptionBuffer(
     const CdmProxyContext::D3D11DecryptContext& decrypt_context) {
   ComPtr<ID3D11Device> crypto_session_device;
   decrypt_context.crypto_session->GetDevice(
       crypto_session_device.ReleaseAndGetAddressOf());

   // If they are the same devices, then there is no reason to reinitialize the
   // buffers.
   if (SameDevices(crypto_session_device, device_))
     return true;

   device_ = crypto_session_device;
   device_->GetImmediateContext(device_context_.ReleaseAndGetAddressOf());

   HRESULT hresult =
       device_context_.CopyTo(video_context_.ReleaseAndGetAddressOf());
   if (FAILED(hresult)) {
     DVLOG(2) << "Failed to get video context.";
     return false;
   }

   // The buffer is staging so that the data can be accessed by the CPU and HW.
   if (!CreateBuffer(device_.Get(), D3D11_USAGE_STAGING, 0,  // no binding.
                     D3D11_CPU_ACCESS_READ | D3D11_CPU_ACCESS_WRITE,
                     encrypted_sample_buffer_.ReleaseAndGetAddressOf())) {
     DVLOG(2) << "Failed to create buffer for encrypted sample.";
     return false;
   }

   // Note that the cpu access flag is 0 because this buffer is used to write the
   // decrypted buffer in HW.
   if (!CreateBuffer(device_.Get(), D3D11_USAGE_DEFAULT,
                     D3D11_BIND_RENDER_TARGET,
                     0,  // no cpu access.
                     decrypted_sample_buffer_.ReleaseAndGetAddressOf())) {
     DVLOG(2) << "Failed to create buffer for decrypted sample.";
     return false;
   }

   if (!CreateBuffer(device_.Get(), D3D11_USAGE_STAGING, 0,  // no binding.
                     D3D11_CPU_ACCESS_READ | D3D11_CPU_ACCESS_WRITE,
                     cpu_accessible_buffer_.ReleaseAndGetAddressOf())) {
     DVLOG(2) << "Failed to create cpu accessible buffer.";
     return false;
   }

   return true;
 }

 bool D3D11Decryptor::CtrDecrypt(
     base::span<const uint8_t> input,
     const std::string& iv,
     const CdmProxyContext::D3D11DecryptContext& context,
     std::vector<uint8_t>* output) {
   output->clear();
   if (input.empty())
     return true;

   if (!CopyDataToBuffer(input, device_context_.Get(),
                         encrypted_sample_buffer_.Get())) {
     return false;
   }

   D3D11_AES_CTR_IV aes_ctr_iv = StringIvToD3D11Iv(iv);

   // The size of the encrypted bytes must be a multiple of 16. See more at
   // https://crbug.com/849466.
   D3D11_ENCRYPTED_BLOCK_INFO block_info = {};
   block_info.NumEncryptedBytesAtBeginning = To16Multiple(input.size());
   DCHECK_LE(block_info.NumEncryptedBytesAtBeginning, kBufferSize);
   block_info.NumBytesInSkipPattern =
       kBufferSize - block_info.NumEncryptedBytesAtBeginning;

   // ID3D11Buffers should be used but since the interface takes ID3D11Texture2D,
   // it is reinterpret cast. See more at https://crbug.com/849466.
   video_context_->DecryptionBlt(
       context.crypto_session,
       reinterpret_cast<ID3D11Texture2D*>(encrypted_sample_buffer_.Get()),
       reinterpret_cast<ID3D11Texture2D*>(decrypted_sample_buffer_.Get()),
       &block_info, context.key_blob_size, context.key_blob, sizeof(aes_ctr_iv),
       &aes_ctr_iv);

   // Because DecryptionBlt() doesn't have a return value, this is a hack to
   // check for decryption operation status. If it has been modified, then there
   // was an error. See more at https://crbug.com/849466.
   HRESULT result = static_cast<HRESULT>(block_info.NumBytesInEncryptPattern);
   if (FAILED(result)) {
     DVLOG(3) << "Decryption error :"
              << logging::SystemErrorCodeToString(result);
     return false;
   }

   device_context_->CopyResource(cpu_accessible_buffer_.Get(),
                                 decrypted_sample_buffer_.Get());
   return CopyDataOutFromBuffer(cpu_accessible_buffer_.Get(), input.size(),
                                device_context_.Get(), output);
 }

 // TODO(crbug.com/845631): This is the same as DecryptCencBuffer(), so it should
 // be deduped.
 bool D3D11Decryptor::SubsampleCtrDecrypt(
     scoped_refptr<DecoderBuffer> encrypted,
     const CdmProxyContext::D3D11DecryptContext& context,
     std::vector<uint8_t>* output) {
   const auto& subsamples = encrypted->decrypt_config()->subsamples();
   std::vector<uint8_t> encrypted_data;
   const uint8_t* data = encrypted->data();
   for (const auto& subsample : subsamples) {
     data += subsample.clear_bytes;
     encrypted_data.insert(encrypted_data.end(), data,
                           data + subsample.cypher_bytes);
     data += subsample.cypher_bytes;
   }

   std::vector<uint8_t> decrypted_data;
   if (!CtrDecrypt(encrypted_data, encrypted->decrypt_config()->iv(), context,
                   &decrypted_data)) {
     return false;
   }

   data = encrypted->data();
   const uint8_t* decrypted_data_ptr = decrypted_data.data();
   for (const auto& subsample : subsamples) {
     output->insert(output->end(), data, data + subsample.clear_bytes);
     data += subsample.clear_bytes;
     output->insert(output->end(), decrypted_data_ptr,
                    decrypted_data_ptr + subsample.cypher_bytes);
     decrypted_data_ptr += subsample.cypher_bytes;
     data += subsample.cypher_bytes;
   }
   return true;
 }

 }  // namespace media
	// Copyright 2018 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "media/gpu/windows/d3d11_decryptor.h"

	#include "base/bind.h"
	#include "base/logging.h"
	#include "base/stl_util.h"
	#include "media/base/decoder_buffer.h"

	namespace media {

	namespace {

	// "A buffer is defined as a single subresource."
	// https://msdn.microsoft.com/en-us/library/windows/desktop/ff476901(v=vs.85).aspx
	const UINT kSubresourceIndex = 0;
	const UINT kWaitIfGPUBusy = 0;

	// This value is somewhat arbitrary but is a multiple of 16 and 4K and is
	// equal to D3D11_REQ_TEXTURE2D_U_OR_V_DIMENSION. Since the buffers are cast
	// to ID3D11Texture2D, setting it as its size should make sense.
	const UINT kBufferSize = 16384;

	// Creates ID3D11Buffer using the values. Return true on success.
	bool CreateBuffer(ID3D11Device* device,
	D3D11_USAGE usage,
	UINT bind_flags,
	UINT cpu_access,
	ID3D11Buffer** out) {
	D3D11_BUFFER_DESC buf_desc = {};

	buf_desc.ByteWidth = kBufferSize;
	buf_desc.BindFlags = bind_flags;
	buf_desc.Usage = usage;
	buf_desc.CPUAccessFlags = cpu_access;

	HRESULT hresult = device->CreateBuffer(&buf_desc, nullptr, out);
	return SUCCEEDED(hresult);
	}

	// Copies \|input\| into \|output\|, the output buffer should be a staging buffer
	// that is CPU writable.
	bool CopyDataToBuffer(base::span<const uint8_t> input,
	ID3D11DeviceContext* device_context,
	ID3D11Buffer* output) {
	D3D11_BUFFER_DESC output_buffer_desc = {};
	output->GetDesc(&output_buffer_desc);

	if (output_buffer_desc.ByteWidth < input.size()) {
	DVLOG(1) << input.size() << " does not fit in "
	<< output_buffer_desc.ByteWidth;
	return false;
	}

	D3D11_MAPPED_SUBRESOURCE map_resource = {};
	HRESULT hresult =
	device_context->Map(output, kSubresourceIndex, D3D11_MAP_WRITE,
	kWaitIfGPUBusy, &map_resource);
	if (FAILED(hresult)) {
	DVLOG(3) << "Failed to map buffer for writing.";
	return false;
	}
	memcpy(map_resource.pData, input.data(), input.size_bytes());
	device_context->Unmap(output, kSubresourceIndex);
	return true;
	}

	// Copies \|input\| into \|output\|. The input buffer is should be a staging buffer
	// that is CPU readable.
	bool CopyDataOutFromBuffer(ID3D11Buffer* input,
	size_t input_size,
	ID3D11DeviceContext* device_context,
	std::vector<uint8_t>* output) {
	D3D11_MAPPED_SUBRESOURCE map_resource = {};
	HRESULT hresult = device_context->Map(
	input, kSubresourceIndex, D3D11_MAP_READ, kWaitIfGPUBusy, &map_resource);
	if (FAILED(hresult)) {
	DVLOG(3) << "Failed to map buffer for reading.";
	return false;
	}
	output->resize(input_size);
	memcpy(output->data(), map_resource.pData, input_size);
	device_context->Unmap(input, kSubresourceIndex);
	return true;
	}

	D3D11_AES_CTR_IV StringIvToD3D11Iv(const std::string& iv) {
	D3D11_AES_CTR_IV d3d11_iv = {};
	DCHECK_LE(iv.size(), 16u);
	memcpy(&d3d11_iv, iv.data(), iv.size());
	return d3d11_iv;
	}

	// Returns true if the entire sample is encrypted.
	bool IsWholeSampleEncrypted(const DecryptConfig& decrypt_config,
	size_t sample_size) {
	const auto& subsamples = decrypt_config.subsamples();
	if (subsamples.size() != 1)
	return false;

	return subsamples.front().clear_bytes == 0 &&
	subsamples.front().cypher_bytes == sample_size;
	}

	// Checks whether \|device1\| is the same component as \|device2\|.
	// Note that comparing COM pointers require using their IUnknowns.
	// https://docs.microsoft.com/en-us/windows/desktop/api/unknwn/nf-unknwn-iunknown-queryinterface(q_)
	bool SameDevices(Microsoft::WRL::ComPtr<ID3D11Device> device1,
	Microsoft::WRL::ComPtr<ID3D11Device> device2) {
	// For the case where both are nullptrs, they aren't devices, so returning
	// false here.
	if (!device1 \|\| !device2)
	return false;
	Microsoft::WRL::ComPtr<IUnknown> device1_iunknown;
	Microsoft::WRL::ComPtr<IUnknown> device2_iunknown;
	HRESULT hr = device1.CopyTo(device1_iunknown.ReleaseAndGetAddressOf());
	if (FAILED(hr))
	return false;
	hr = device2.CopyTo(device2_iunknown.ReleaseAndGetAddressOf());
	if (FAILED(hr))
	return false;
	return device1_iunknown == device2_iunknown;
	}

	// Returns a value that is bigger than or equal to \|num\| that is a
	// multiple of 16.
	// E.g. num = 15 returns 16, 17 returns 32.
	UINT To16Multiple(size_t num) {
	return ((num + 15) >> 4) << 4;
	}

	} // namespace

	D3D11Decryptor::D3D11Decryptor(CdmProxyContext* cdm_proxy_context)
	: cdm_proxy_context_(cdm_proxy_context), weak_factory_(this) {
	DCHECK(cdm_proxy_context_);
	}

	D3D11Decryptor::~D3D11Decryptor() {}

	void D3D11Decryptor::RegisterNewKeyCB(StreamType stream_type,
	const NewKeyCB& new_key_cb) {
	// TODO(xhwang): Use RegisterNewKeyCB() on CdmContext, and remove
	// RegisterNewKeyCB from Decryptor interface.
	NOTREACHED();
	}

	void D3D11Decryptor::Decrypt(StreamType stream_type,
	scoped_refptr<DecoderBuffer> encrypted,
	const DecryptCB& decrypt_cb) {
	if (encrypted->end_of_stream()) {
	decrypt_cb.Run(kSuccess, encrypted);
	return;
	}

	const auto* decrypt_config = encrypted->decrypt_config();
	if (!decrypt_config) {
	// Not encrypted, nothing to do.
	decrypt_cb.Run(kSuccess, encrypted);
	return;
	}

	if (decrypt_config->HasPattern()) {
	DVLOG(3) << "Cannot handle pattern decryption.";
	decrypt_cb.Run(kError, nullptr);
	return;
	}

	auto context = cdm_proxy_context_->GetD3D11DecryptContext(
	CdmProxy::KeyType::kDecryptOnly, decrypt_config->key_id());
	if (!context) {
	decrypt_cb.Run(kNoKey, nullptr);
	return;
	}

	// Because DecryptionBlt() implementation checks whether the device, buffers,
	// and the crypto session are from the same device, the buffers have to be
	// recreated.
	if (!InitializeDecryptionBuffer(*context)) {
	decrypt_cb.Run(kError, nullptr);
	return;
	}

	std::vector<uint8_t> output;
	if (IsWholeSampleEncrypted(*encrypted->decrypt_config(),
	encrypted->data_size())) {
	if (!CtrDecrypt(base::make_span(encrypted->data(), encrypted->data_size()),
	encrypted->decrypt_config()->iv(), *context, &output)) {
	decrypt_cb.Run(kError, nullptr);
	return;
	}
	} else {
	if (!SubsampleCtrDecrypt(encrypted, *context, &output)) {
	decrypt_cb.Run(kError, nullptr);
	return;
	}
	}

	auto decoder_buffer = DecoderBuffer::CopyFrom(output.data(), output.size());
	decoder_buffer->set_timestamp(encrypted->timestamp());
	decoder_buffer->set_duration(encrypted->duration());
	decoder_buffer->set_is_key_frame(encrypted->is_key_frame());
	decoder_buffer->CopySideDataFrom(encrypted->side_data(),
	encrypted->side_data_size());
	decrypt_cb.Run(kSuccess, decoder_buffer);
	}

	void D3D11Decryptor::CancelDecrypt(StreamType stream_type) {
	// Decrypt() calls the DecryptCB synchronously so there's nothing to cancel.
	}

	void D3D11Decryptor::InitializeAudioDecoder(const AudioDecoderConfig& config,
	const DecoderInitCB& init_cb) {
	// D3D11Decryptor does not support audio decoding.
	init_cb.Run(false);
	}

	void D3D11Decryptor::InitializeVideoDecoder(const VideoDecoderConfig& config,
	const DecoderInitCB& init_cb) {
	// D3D11Decryptor does not support video decoding.
	init_cb.Run(false);
	}

	void D3D11Decryptor::DecryptAndDecodeAudio(
	scoped_refptr<DecoderBuffer> encrypted,
	const AudioDecodeCB& audio_decode_cb) {
	NOTREACHED() << "D3D11Decryptor does not support audio decoding";
	}

	void D3D11Decryptor::DecryptAndDecodeVideo(
	scoped_refptr<DecoderBuffer> encrypted,
	const VideoDecodeCB& video_decode_cb) {
	NOTREACHED() << "D3D11Decryptor does not support video decoding";
	}

	void D3D11Decryptor::ResetDecoder(StreamType stream_type) {
	NOTREACHED() << "D3D11Decryptor does not support audio/video decoding";
	}

	void D3D11Decryptor::DeinitializeDecoder(StreamType stream_type) {
	// D3D11Decryptor does not support audio/video decoding, but since this can be
	// called any time after InitializeAudioDecoder/InitializeVideoDecoder,
	// nothing to be done here.
	}

	bool D3D11Decryptor::InitializeDecryptionBuffer(
	const CdmProxyContext::D3D11DecryptContext& decrypt_context) {
	ComPtr<ID3D11Device> crypto_session_device;
	decrypt_context.crypto_session->GetDevice(
	crypto_session_device.ReleaseAndGetAddressOf());

	// If they are the same devices, then there is no reason to reinitialize the
	// buffers.
	if (SameDevices(crypto_session_device, device_))
	return true;

	device_ = crypto_session_device;
	device_->GetImmediateContext(device_context_.ReleaseAndGetAddressOf());

	HRESULT hresult =
	device_context_.CopyTo(video_context_.ReleaseAndGetAddressOf());
	if (FAILED(hresult)) {
	DVLOG(2) << "Failed to get video context.";
	return false;
	}

	// The buffer is staging so that the data can be accessed by the CPU and HW.
	if (!CreateBuffer(device_.Get(), D3D11_USAGE_STAGING, 0, // no binding.
	D3D11_CPU_ACCESS_READ \| D3D11_CPU_ACCESS_WRITE,
	encrypted_sample_buffer_.ReleaseAndGetAddressOf())) {
	DVLOG(2) << "Failed to create buffer for encrypted sample.";
	return false;
	}

	// Note that the cpu access flag is 0 because this buffer is used to write the
	// decrypted buffer in HW.
	if (!CreateBuffer(device_.Get(), D3D11_USAGE_DEFAULT,
	D3D11_BIND_RENDER_TARGET,
	0, // no cpu access.
	decrypted_sample_buffer_.ReleaseAndGetAddressOf())) {
	DVLOG(2) << "Failed to create buffer for decrypted sample.";
	return false;
	}

	if (!CreateBuffer(device_.Get(), D3D11_USAGE_STAGING, 0, // no binding.
	D3D11_CPU_ACCESS_READ \| D3D11_CPU_ACCESS_WRITE,
	cpu_accessible_buffer_.ReleaseAndGetAddressOf())) {
	DVLOG(2) << "Failed to create cpu accessible buffer.";
	return false;
	}

	return true;
	}

	bool D3D11Decryptor::CtrDecrypt(
	base::span<const uint8_t> input,
	const std::string& iv,
	const CdmProxyContext::D3D11DecryptContext& context,
	std::vector<uint8_t>* output) {
	output->clear();
	if (input.empty())
	return true;

	if (!CopyDataToBuffer(input, device_context_.Get(),
	encrypted_sample_buffer_.Get())) {
	return false;
	}

	D3D11_AES_CTR_IV aes_ctr_iv = StringIvToD3D11Iv(iv);

	// The size of the encrypted bytes must be a multiple of 16. See more at
	// https://crbug.com/849466.
	D3D11_ENCRYPTED_BLOCK_INFO block_info = {};
	block_info.NumEncryptedBytesAtBeginning = To16Multiple(input.size());
	DCHECK_LE(block_info.NumEncryptedBytesAtBeginning, kBufferSize);
	block_info.NumBytesInSkipPattern =
	kBufferSize - block_info.NumEncryptedBytesAtBeginning;

	// ID3D11Buffers should be used but since the interface takes ID3D11Texture2D,
	// it is reinterpret cast. See more at https://crbug.com/849466.
	video_context_->DecryptionBlt(
	context.crypto_session,
	reinterpret_cast<ID3D11Texture2D*>(encrypted_sample_buffer_.Get()),
	reinterpret_cast<ID3D11Texture2D*>(decrypted_sample_buffer_.Get()),
	&block_info, context.key_blob_size, context.key_blob, sizeof(aes_ctr_iv),
	&aes_ctr_iv);

	// Because DecryptionBlt() doesn't have a return value, this is a hack to
	// check for decryption operation status. If it has been modified, then there
	// was an error. See more at https://crbug.com/849466.
	HRESULT result = static_cast<HRESULT>(block_info.NumBytesInEncryptPattern);
	if (FAILED(result)) {
	DVLOG(3) << "Decryption error :"
	<< logging::SystemErrorCodeToString(result);
	return false;
	}

	device_context_->CopyResource(cpu_accessible_buffer_.Get(),
	decrypted_sample_buffer_.Get());
	return CopyDataOutFromBuffer(cpu_accessible_buffer_.Get(), input.size(),
	device_context_.Get(), output);
	}

	// TODO(crbug.com/845631): This is the same as DecryptCencBuffer(), so it should
	// be deduped.
	bool D3D11Decryptor::SubsampleCtrDecrypt(
	scoped_refptr<DecoderBuffer> encrypted,
	const CdmProxyContext::D3D11DecryptContext& context,
	std::vector<uint8_t>* output) {
	const auto& subsamples = encrypted->decrypt_config()->subsamples();
	std::vector<uint8_t> encrypted_data;
	const uint8_t* data = encrypted->data();
	for (const auto& subsample : subsamples) {
	data += subsample.clear_bytes;
	encrypted_data.insert(encrypted_data.end(), data,
	data + subsample.cypher_bytes);
	data += subsample.cypher_bytes;
	}

	std::vector<uint8_t> decrypted_data;
	if (!CtrDecrypt(encrypted_data, encrypted->decrypt_config()->iv(), context,
	&decrypted_data)) {
	return false;
	}

	data = encrypted->data();
	const uint8_t* decrypted_data_ptr = decrypted_data.data();
	for (const auto& subsample : subsamples) {
	output->insert(output->end(), data, data + subsample.clear_bytes);
	data += subsample.clear_bytes;
	output->insert(output->end(), decrypted_data_ptr,
	decrypted_data_ptr + subsample.cypher_bytes);
	decrypted_data_ptr += subsample.cypher_bytes;
	data += subsample.cypher_bytes;
	}
	return true;
	}

	} // namespace media