1 files changed, 85 insertions, 0 deletions
diff --git a/audio_utils/include/audio_utils/spdif/SPDIFEncoder.h b/audio_utils/include/audio_utils/spdif/SPDIFEncoder.h
new file mode 100644
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--- /dev/null
+++ b/audio_utils/include/audio_utils/spdif/SPDIFEncoder.h
@@ -0,0 +1,85 @@
+/*
+**
+** Copyright 2014, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#ifndef ANDROID_AUDIO_SPDIF_ENCODER_H
+#define ANDROID_AUDIO_SPDIF_ENCODER_H
+
+#include <stdint.h>
+#include <audio_utils/spdif/FrameScanner.h>
+
+namespace android {
+
+/**
+ * Scan the incoming byte stream for a frame sync.
+ * Then wrap the encoded frame in a data burst and send it as if it were PCM.
+ * The receiver will see the data burst header and decode the wrapped frame.
+ */
+#define SPDIF_MAX_CHANNELS          8
+#define SPDIF_ENCODED_CHANNEL_COUNT 2
+
+class SPDIFEncoder {
+public:
+
+    SPDIFEncoder();
+    virtual ~SPDIFEncoder();
+
+    ssize_t write( const void* buffer, size_t numBytes );
+
+    // Called by SPDIFEncoder when it is ready to output a data burst.
+    // Must be implemented by caller.
+    virtual ssize_t writeOutput( const void* buffer, size_t numBytes ) = 0;
+
+    uint32_t getRateMultiplier() const { return mRateMultiplier; }
+    uint32_t getBurstFrames() const { return mBurstFrames; }
+    int      getBytesPerOutputFrame();
+
+protected:
+    void   clearBurstBuffer();
+
+    void   writeBurstBufferShorts(const uint16_t* buffer, size_t numBytes);
+    void   writeBurstBufferBytes(const uint8_t* buffer, size_t numBytes);
+    void   sendZeroPad();
+    void   flushBurstBuffer();
+    size_t startDataBurst();
+
+    // State machine states.
+    enum State {
+        STATE_IDLE,   // Waiting to sync with encoded data.
+        STATE_BURST,  // In the middle of a data burst.
+    };
+
+    // Works with various formats including AC3.
+    FrameScanner *mFramer;
+
+    State     mState;
+    uint32_t  mSampleRate;
+    size_t    mFrameSize;
+    uint16_t *mBurstBuffer; // ALSA wants to get SPDIF data as shorts.
+    size_t    mBurstBufferSizeBytes;
+    uint32_t  mRateMultiplier;
+    uint32_t  mBurstFrames;
+    size_t    mByteCursor;
+    int       mBitstreamNumber;
+    size_t    mPayloadBytesPending;
+
+    static const unsigned short kSPDIFSync1; // Pa
+    static const unsigned short kSPDIFSync2; // Pb
+};
+
+}  // namespace android
+
+#endif  // ANDROID_AUDIO_SPDIF_ENCODER_H