Fix mono gapless playback for decoders that output stereo

The old AAC decoder always outputs stereo, even for mono source material, so we
need to use the number of channels of the output when calculating the number of
bytes to skip, not the number of channels in the source.
This makes OMXCodec skip the right amount of data, and prevents NuPlayer from
writing half a frame and then asserting when the AudioSink doesn't accept it.
Also move use of the SkipCutBuffer from NuPlayer to ACodec, so that it also
works when using the new Java APIs, and make SkipCutBuffer derive from RefBase.
b/774846

Change-Id: I34df9fea3e6730617eae559afaa556f4085ef0a0

1 files changed, 4 insertions, 2 deletions

diff --git a/include/media/stagefright/SkipCutBuffer.h b/include/media/stagefright/SkipCutBuffer.h
index 27851ca..2653b53 100644
--- a/include/media/stagefright/SkipCutBuffer.h
+++ b/include/media/stagefright/SkipCutBuffer.h
@@ -27,12 +27,11 @@ namespace android {
  * utility class to cut the start and end off a stream of data in MediaBuffers
  *
  */
-class SkipCutBuffer {
+class SkipCutBuffer: public RefBase {
  public:
     // 'skip' is the number of bytes to skip from the beginning
     // 'cut' is the number of bytes to cut from the end
     SkipCutBuffer(int32_t skip, int32_t cut);
-    virtual ~SkipCutBuffer();
 
     // Submit one MediaBuffer for skipping and cutting. This may consume all or
     // some of the data in the buffer, or it may add data to it.
@@ -42,6 +41,9 @@ class SkipCutBuffer {
     void clear();
     size_t size(); // how many bytes are currently stored in the buffer
 
+ protected:
+    virtual ~SkipCutBuffer();
+
  private:
     void write(const char *src, size_t num);
     size_t read(char *dst, size_t num);