media: Allow config change between clear and encrypted streams

media/filters/decrypting_audio_decoder.cc

 // 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.
 
 #include "media/filters/decrypting_audio_decoder.h"
 
 #include <stdint.h>
 
 #include <cstdlib>
 
@@ skipping 45 matching lines @@
                                         const OutputCB& output_cb) {
   DVLOG(2) << "Initialize()";
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(decode_cb_.is_null());
   DCHECK(reset_cb_.is_null());
 
   weak_this_ = weak_factory_.GetWeakPtr();
   init_cb_ = BindToCurrentLoop(init_cb);
   output_cb_ = BindToCurrentLoop(output_cb);
 
-  // TODO(xhwang): We should be able to DCHECK config.IsValidConfig() and
-  // config.is_encrypted().
+  // TODO(xhwang): We should be able to DCHECK config.IsValidConfig().
   if (!config.IsValidConfig()) {
     DLOG(ERROR) << "Invalid audio stream config.";
     base::ResetAndReturn(&init_cb_).Run(false);
     return;
   }
 
-  // DecryptingAudioDecoder only accepts potentially encrypted stream.
-  if (!config.is_encrypted()) {
-    base::ResetAndReturn(&init_cb_).Run(false);
-    return;
-  }
-
   config_ = config;
 
   if (state_ == kUninitialized) {
+    DCHECK(config.is_encrypted());

[Joey Parrish, 2016/12/01 22:28:10]

This is protecting the renderer?  Might be good to have a comment to that
effect, since it appears to be protecting the decoder.

[ddorwin, 2016/12/05 23:53:04]

There should probably be a comment/TODO with the crbug.

[xhwang, 2016/12/16 20:12:28]

joeyparrish: This is an internal contract between DecoderSelector and
DecryptingAudioDecoder. Today we would only choose DAD when the stream is
encrypted.

ddorwin: comment added. This check will probably stay and I don't feel we need a
TODO here.

     DCHECK(cdm_context);
     if (!cdm_context->GetDecryptor()) {
       MEDIA_LOG(DEBUG, media_log_) << GetDisplayName() << ": no decryptor";
       base::ResetAndReturn(&init_cb_).Run(false);
       return;
     }
 
     decryptor_ = cdm_context->GetDecryptor();
   } else {
-    // Reinitialization (i.e. upon a config change)
+    // Reinitialization (i.e. upon a config change, the new config can be

[ddorwin, 2016/12/05 23:53:04]

The new text seems like a separate thought and maybe a new sentence outside the
().

[xhwang, 2016/12/16 20:12:28]

Done.

+    // encrypted or clear).
     decryptor_->DeinitializeDecoder(Decryptor::kAudio);
   }
 
   InitializeDecoder();
 }
 
 void DecryptingAudioDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
                                     const DecodeCB& decode_cb) {
   DVLOG(3) << "Decode()";
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ skipping 253 matching lines @@
     }
 
     frame->set_timestamp(current_time);
     timestamp_helper_->AddFrames(frame->frame_count());
 
     output_cb_.Run(frame);
   }
 }
 
 }  // namespace media