/*
* 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.
*/
#define LOG_TAG "AudioSPDIF"
#include <string.h>
#include <utils/Log.h>
#include <audio_utils/spdif/FrameScanner.h>
#include "AC3FrameScanner.h"
namespace android {
// These values are from the AC3 spec. Do not change them.
const uint8_t AC3FrameScanner::kSyncBytes[] = { 0x0B, 0x77 };
const uint16_t AC3FrameScanner::kAC3SampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES]
= { 48000, 44100, 32000 };
// Table contains number of 16-bit words in an AC3 frame.
// From AC3 spec table 5.13
const uint16_t AC3FrameScanner::kAC3FrameSizeTable[AC3_NUM_FRAME_SIZE_TABLE_ENTRIES]
[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES] = {
{ 64, 69, 96 },
{ 64, 70, 96 },
{ 80, 87, 120 },
{ 80, 88, 120 },
{ 96, 104, 144 },
{ 96, 105, 144 },
{ 112, 121, 168 },
{ 112, 122, 168 },
{ 128, 139, 192 },
{ 128, 140, 192 },
{ 160, 174, 240 },
{ 160, 175, 240 },
{ 192, 208, 288 },
{ 192, 209, 288 },
{ 224, 243, 336 },
{ 224, 244, 336 },
{ 256, 278, 384 },
{ 256, 279, 384 },
{ 320, 348, 480 },
{ 320, 349, 480 },
{ 384, 417, 576 },
{ 384, 418, 576 },
{ 448, 487, 672 },
{ 448, 488, 672 },
{ 512, 557, 768 },
{ 512, 558, 768 },
{ 640, 696, 960 },
{ 640, 697, 960 },
{ 768, 835, 1152 },
{ 768, 836, 1152 },
{ 896, 975, 1344 },
{ 896, 976, 1344 },
{ 1024, 1114, 1536 },
{ 1024, 1115, 1536 },
{ 1152, 1253, 1728 },
{ 1152, 1254, 1728 },
{ 1280, 1393, 1920 },
{ 1280, 1394, 1920 }
};
const uint16_t AC3FrameScanner::kEAC3ReducedSampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES]
= { 24000, 22050, 16000 };
const uint16_t
AC3FrameScanner::kEAC3BlocksPerFrameTable[EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES]
= { 1, 2, 3, 6 };
// Defined in IEC61937-2
#define SPDIF_DATA_TYPE_AC3 1
#define SPDIF_DATA_TYPE_E_AC3 21
#define AC3_STREAM_TYPE_0 0
#define AC3_STREAM_TYPE_1 1
#define AC3_STREAM_TYPE_2 2
// -----------------------------------------------------------------------------
// Scanner for AC3 byte streams.
AC3FrameScanner::AC3FrameScanner()
: FrameScanner(SPDIF_DATA_TYPE_AC3,
AC3FrameScanner::kSyncBytes,
sizeof(AC3FrameScanner::kSyncBytes), 6)
, mStreamType(0)
, mSubstreamID(0)
{
mAudioBlocksPerSyncFrame = 6;
memset(mSubstreamBlockCounts, 0, sizeof(mSubstreamBlockCounts));
}
AC3FrameScanner::~AC3FrameScanner()
{
}
int AC3FrameScanner::getSampleFramesPerSyncFrame() const
{
return mRateMultiplier
* AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK;
}
void AC3FrameScanner::resetBurst()
{
for (int i = 0; i < EAC3_MAX_SUBSTREAMS; i++) {
if (mSubstreamBlockCounts[i] >= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK) {
mSubstreamBlockCounts[i] -= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK;
} else if (mSubstreamBlockCounts[i] > 0) {
ALOGW("EAC3 substream[%d] has only %d audio blocks!",
i, mSubstreamBlockCounts[i]);
mSubstreamBlockCounts[i] = 0;
}
}
}
// Per IEC 61973-3:5.3.3, for E-AC3 burst-length shall be in bytes.
uint16_t AC3FrameScanner::convertBytesToLengthCode(uint16_t numBytes) const
{
return (mDataType == SPDIF_DATA_TYPE_E_AC3) ? numBytes : numBytes * 8;
}
// per IEC 61973-3 Paragraph 5.3.3
// We have to send 6 audio blocks on all active substreams.
// Substream zero must be the first.
// We don't know if we have all the blocks we need until we see
// the 7th block of substream#0.
bool AC3FrameScanner::isFirstInBurst()
{
if (mDataType == SPDIF_DATA_TYPE_E_AC3) {
if (((mStreamType == AC3_STREAM_TYPE_0)
|| (mStreamType == AC3_STREAM_TYPE_2))
&& (mSubstreamID == 0)
// The ">" is intentional. We have to see the beginning
// of the block in the next burst before we can send
// the current burst.
&& (mSubstreamBlockCounts[0] > AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK)) {
return true;
}
}
return false;
}
bool AC3FrameScanner::isLastInBurst()
{
// For EAC3 we don't know if we are the end until we see a
// frame that must be at the beginning. See isFirstInBurst().
return (mDataType != SPDIF_DATA_TYPE_E_AC3); // Just one AC3 frame per burst.
}
// TODO Use BitFieldParser
// Parse AC3 header.
// Detect whether the stream is AC3 or EAC3. Extract data depending on type.
//
// @return true if valid
bool AC3FrameScanner::parseHeader()
{
// Interpret bsid based on paragraph E2.3.1.6 of EAC3 spec.
uint32_t bsid = mHeaderBuffer[5] >> 3; // bitstream ID
// Check BSID to see if this is EAC3 or regular AC3.
// These arbitrary BSID numbers do not have any names in the spec.
if ((bsid > 10) && (bsid <= 16)) {
mDataType = SPDIF_DATA_TYPE_E_AC3;
} else if (bsid <= 8) {
mDataType = SPDIF_DATA_TYPE_AC3;
} else {
ALOGW("AC3 bsid = %d not supported", bsid);
return false;
}
// bitstream mode, main, commentary, etc.
uint32_t bsmod = mHeaderBuffer[5] & 7;
mDataTypeInfo = bsmod; // as per IEC61937-3, table 3.
// The names fscod, frmsiz are from the AC3 spec.
uint32_t fscod = mHeaderBuffer[4] >> 6;
if (mDataType == SPDIF_DATA_TYPE_E_AC3) {
mStreamType = mHeaderBuffer[2] >> 6; // strmtyp in spec
mSubstreamID = (mHeaderBuffer[2] >> 3) & 0x07;
// Frame size is explicit in EAC3. Paragraph E2.3.1.3
uint32_t frmsiz = ((mHeaderBuffer[2] & 0x07) << 8) + mHeaderBuffer[3];
mFrameSizeBytes = (frmsiz + 1) * sizeof(int16_t);
uint32_t numblkscod = 3; // 6 blocks default
if (fscod == 3) {
uint32_t fscod2 = (mHeaderBuffer[4] >> 4) & 0x03;
if (fscod2 >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) {
ALOGW("Invalid EAC3 fscod2 = %d", fscod2);
return false;
} else {
mSampleRate = kEAC3ReducedSampleRateTable[fscod2];
}
} else {
mSampleRate = kAC3SampleRateTable[fscod];
numblkscod = (mHeaderBuffer[4] >> 4) & 0x03;
}
mRateMultiplier = EAC3_RATE_MULTIPLIER; // per IEC 61973-3 Paragraph 5.3.3
// Don't send data burst until we have 6 blocks per substream.
mAudioBlocksPerSyncFrame = kEAC3BlocksPerFrameTable[numblkscod];
// Keep track of how many audio blocks we have for each substream.
// This should be safe because mSubstreamID is ANDed with 0x07 above.
// And the array is allocated as [8].
if ((mStreamType == AC3_STREAM_TYPE_0)
|| (mStreamType == AC3_STREAM_TYPE_2)) {
mSubstreamBlockCounts[mSubstreamID] += mAudioBlocksPerSyncFrame;
}
// Print enough so we can see all the substreams.
ALOGD_IF((mFormatDumpCount < 3*8 ),
"EAC3 mStreamType = %d, mSubstreamID = %d",
mStreamType, mSubstreamID);
} else { // regular AC3
// Extract sample rate and frame size from codes.
uint32_t frmsizcod = mHeaderBuffer[4] & 0x3F; // frame size code
if (fscod >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) {
ALOGW("Invalid AC3 sampleRateCode = %d", fscod);
return false;
} else if (frmsizcod >= AC3_NUM_FRAME_SIZE_TABLE_ENTRIES) {
ALOGW("Invalid AC3 frameSizeCode = %d", frmsizcod);
return false;
} else {
mSampleRate = kAC3SampleRateTable[fscod];
mRateMultiplier = 1;
mFrameSizeBytes = sizeof(uint16_t)
* kAC3FrameSizeTable[frmsizcod][fscod];
}
mAudioBlocksPerSyncFrame = 6;
}
ALOGI_IF((mFormatDumpCount == 0),
"AC3 frame rate = %d * %d, size = %zu, audioBlocksPerSyncFrame = %d",
mSampleRate, mRateMultiplier, mFrameSizeBytes, mAudioBlocksPerSyncFrame);
mFormatDumpCount++;
return true;
}
} // namespace android