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/*
* Copyright (C) 2010 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_NDEBUG 0
#define LOG_TAG "G711Decoder"
#include <utils/Log.h>
#include "G711Decoder.h"
#include <media/stagefright/MediaBufferGroup.h>
#include <media/stagefright/MediaDebug.h>
#include <media/stagefright/MediaDefs.h>
#include <media/stagefright/MediaErrors.h>
#include <media/stagefright/MetaData.h>
static const size_t kMaxNumSamplesPerFrame = 16384;
namespace android {
G711Decoder::G711Decoder(const sp<MediaSource> &source)
: mSource(source),
mStarted(false),
mBufferGroup(NULL) {
}
G711Decoder::~G711Decoder() {
if (mStarted) {
stop();
}
}
status_t G711Decoder::start(MetaData *params) {
CHECK(!mStarted);
const char *mime;
CHECK(mSource->getFormat()->findCString(kKeyMIMEType, &mime));
mIsMLaw = false;
if (!strcasecmp(mime, MEDIA_MIMETYPE_AUDIO_G711_MLAW)) {
mIsMLaw = true;
} else if (strcasecmp(mime, MEDIA_MIMETYPE_AUDIO_G711_ALAW)) {
return ERROR_UNSUPPORTED;
}
mBufferGroup = new MediaBufferGroup;
mBufferGroup->add_buffer(
new MediaBuffer(kMaxNumSamplesPerFrame * sizeof(int16_t)));
mSource->start();
mStarted = true;
return OK;
}
status_t G711Decoder::stop() {
CHECK(mStarted);
delete mBufferGroup;
mBufferGroup = NULL;
mSource->stop();
mStarted = false;
return OK;
}
sp<MetaData> G711Decoder::getFormat() {
sp<MetaData> srcFormat = mSource->getFormat();
int32_t numChannels;
int32_t sampleRate;
CHECK(srcFormat->findInt32(kKeyChannelCount, &numChannels));
CHECK(srcFormat->findInt32(kKeySampleRate, &sampleRate));
sp<MetaData> meta = new MetaData;
meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_RAW);
meta->setInt32(kKeyChannelCount, numChannels);
meta->setInt32(kKeySampleRate, sampleRate);
int64_t durationUs;
if (srcFormat->findInt64(kKeyDuration, &durationUs)) {
meta->setInt64(kKeyDuration, durationUs);
}
meta->setCString(kKeyDecoderComponent, "G711Decoder");
return meta;
}
status_t G711Decoder::read(
MediaBuffer **out, const ReadOptions *options) {
status_t err;
*out = NULL;
int64_t seekTimeUs;
ReadOptions::SeekMode mode;
if (options && options->getSeekTo(&seekTimeUs, &mode)) {
CHECK(seekTimeUs >= 0);
} else {
seekTimeUs = -1;
}
MediaBuffer *inBuffer;
err = mSource->read(&inBuffer, options);
if (err != OK) {
return err;
}
if (inBuffer->range_length() > kMaxNumSamplesPerFrame) {
LOGE("input buffer too large (%d).", inBuffer->range_length());
inBuffer->release();
inBuffer = NULL;
return ERROR_UNSUPPORTED;
}
int64_t timeUs;
CHECK(inBuffer->meta_data()->findInt64(kKeyTime, &timeUs));
const uint8_t *inputPtr =
(const uint8_t *)inBuffer->data() + inBuffer->range_offset();
MediaBuffer *outBuffer;
CHECK_EQ(mBufferGroup->acquire_buffer(&outBuffer), OK);
if (mIsMLaw) {
DecodeMLaw(
static_cast<int16_t *>(outBuffer->data()),
inputPtr, inBuffer->range_length());
} else {
DecodeALaw(
static_cast<int16_t *>(outBuffer->data()),
inputPtr, inBuffer->range_length());
}
// Each 8-bit byte is converted into a 16-bit sample.
outBuffer->set_range(0, inBuffer->range_length() * 2);
outBuffer->meta_data()->setInt64(kKeyTime, timeUs);
inBuffer->release();
inBuffer = NULL;
*out = outBuffer;
return OK;
}
// static
void G711Decoder::DecodeALaw(
int16_t *out, const uint8_t *in, size_t inSize) {
while (inSize-- > 0) {
int32_t x = *in++;
int32_t ix = x ^ 0x55;
ix &= 0x7f;
int32_t iexp = ix >> 4;
int32_t mant = ix & 0x0f;
if (iexp > 0) {
mant += 16;
}
mant = (mant << 4) + 8;
if (iexp > 1) {
mant = mant << (iexp - 1);
}
*out++ = (x > 127) ? mant : -mant;
}
}
// static
void G711Decoder::DecodeMLaw(
int16_t *out, const uint8_t *in, size_t inSize) {
while (inSize-- > 0) {
int32_t x = *in++;
int32_t mantissa = ~x;
int32_t exponent = (mantissa >> 4) & 7;
int32_t segment = exponent + 1;
mantissa &= 0x0f;
int32_t step = 4 << segment;
int32_t abs = (0x80l << exponent) + step * mantissa + step / 2 - 4 * 33;
*out++ = (x < 0x80) ? -abs : abs;
}
}
} // namespace android
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