media: Prefer decrypting pipeline when CDM is attached

media/base/audio_decoder_config.h

 // Copyright (c) 2012 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.
 
 #ifndef MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
 #define MEDIA_BASE_AUDIO_DECODER_CONFIG_H_
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
+#include "base/logging.h"
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "media/base/audio_codecs.h"
 #include "media/base/channel_layout.h"
 #include "media/base/encryption_scheme.h"
 #include "media/base/media_export.h"
+#include "media/base/media_util.h"
 #include "media/base/sample_format.h"
 
 namespace media {
 
 // TODO(dalecurtis): FFmpeg API uses |bytes_per_channel| instead of
 // |bits_per_channel|, we should switch over since bits are generally confusing
 // to work with.
 class MEDIA_EXPORT AudioDecoderConfig {
  public:
   // Constructs an uninitialized object. Clients should call Initialize() with
@@ skipping 51 matching lines @@
   // Whether the audio stream is potentially encrypted.
   // Note that in a potentially encrypted audio stream, individual buffers
   // can be encrypted or not encrypted.
   bool is_encrypted() const { return encryption_scheme_.is_encrypted(); }
 
   // Encryption scheme used for encrypted buffers.
   const EncryptionScheme& encryption_scheme() const {
     return encryption_scheme_;
   }
 
+  // Sets the config to be encrypted or not encrypted manually. This can be

[DaleCurtis, 2017/02/24 18:03:50]

Can't use hacker_style() for such a big method; move to .cc and rename
SetIsEncrypted().

[xhwang, 2017/02/24 18:18:15]

Done.

+  // useful for decryptors that decrypts an encrypted stream to a clear stream,
+  // or for decoder selectors that wants to select decrypting decoders instead
+  // of clear decoders.
+  void set_is_encrypted(bool is_encrypted) {
+    if (!is_encrypted) {
+      DCHECK(encryption_scheme_.is_encrypted()) << "Config is already clear.";
+      encryption_scheme_ = Unencrypted();
+    } else {
+      DCHECK(!encryption_scheme_.is_encrypted())
+          << "Config is already encrypted.";
+      // TODO(xhwang): This is only used to guide decoder selection, so set
+      // a common encryption scheme that should be supported by all decrypting
+      // decoders. We should be able to remove this when we support switching
+      // decoders at run time. See http://crbug.com/695595
+      encryption_scheme_ = AesCtrEncryptionScheme();
+    }
+  }
+
  private:
   AudioCodec codec_;
   SampleFormat sample_format_;
   int bytes_per_channel_;
   ChannelLayout channel_layout_;
   int samples_per_second_;
   int bytes_per_frame_;
   std::vector<uint8_t> extra_data_;
   EncryptionScheme encryption_scheme_;
 
   // |seek_preroll_| is the duration of the data that the decoder must decode
   // before the decoded data is valid.
   base::TimeDelta seek_preroll_;
 
   // |codec_delay_| is the number of frames the decoder should discard before
   // returning decoded data.  This value can include both decoder delay as well
   // as padding added during encoding.
   int codec_delay_;
 
   // Not using DISALLOW_COPY_AND_ASSIGN here intentionally to allow the compiler
   // generated copy constructor and assignment operator. Since the extra data is
   // typically small, the performance impact is minimal.
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_DECODER_CONFIG_H_