media/libstagefright/WAVExtractor.cpp

/*
 * Copyright (C) 2009 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 "WAVExtractor"
#include <utils/Log.h>

#include "include/WAVExtractor.h"

#include <media/stagefright/DataSource.h>
#include <media/stagefright/MediaBufferGroup.h>
#include <media/stagefright/MediaDebug.h>
#include <media/stagefright/MediaDefs.h>
#include <media/stagefright/MediaErrors.h>
#include <media/stagefright/MediaSource.h>
#include <media/stagefright/MetaData.h>
#include <utils/String8.h>

namespace android {

static uint16_t WAVE_FORMAT_PCM = 1;

static uint32_t U32_LE_AT(const uint8_t *ptr) {
    return ptr[3] << 24 | ptr[2] << 16 | ptr[1] << 8 | ptr[0];
}

static uint16_t U16_LE_AT(const uint8_t *ptr) {
    return ptr[1] << 8 | ptr[0];
}

struct WAVSource : public MediaSource {
    WAVSource(
            const sp<DataSource> &dataSource,
            const sp<MetaData> &meta,
            int32_t bitsPerSample,
            off_t offset, size_t size);

    virtual status_t start(MetaData *params = NULL);
    virtual status_t stop();
    virtual sp<MetaData> getFormat();

    virtual status_t read(
            MediaBuffer **buffer, const ReadOptions *options = NULL);

protected:
    virtual ~WAVSource();

private:
    static const size_t kMaxFrameSize;

    sp<DataSource> mDataSource;
    sp<MetaData> mMeta;
    int32_t mSampleRate;
    int32_t mNumChannels;
    int32_t mBitsPerSample;
    off_t mOffset;
    size_t mSize;
    bool mStarted;
    MediaBufferGroup *mGroup;
    off_t mCurrentPos;

    WAVSource(const WAVSource &);
    WAVSource &operator=(const WAVSource &);
};

WAVExtractor::WAVExtractor(const sp<DataSource> &source)
    : mDataSource(source),
      mValidFormat(false) {
    mInitCheck = init();
}

WAVExtractor::~WAVExtractor() {
}

sp<MetaData> WAVExtractor::getMetaData() {
    sp<MetaData> meta = new MetaData;

    if (mInitCheck != OK) {
        return meta;
    }

    meta->setCString(kKeyMIMEType, "audio/x-wav");

    return meta;
}

size_t WAVExtractor::countTracks() {
    return mInitCheck == OK ? 1 : 0;
}

sp<MediaSource> WAVExtractor::getTrack(size_t index) {
    if (mInitCheck != OK || index > 0) {
        return NULL;
    }

    return new WAVSource(
            mDataSource, mTrackMeta,
            mBitsPerSample, mDataOffset, mDataSize);
}

sp<MetaData> WAVExtractor::getTrackMetaData(
        size_t index, uint32_t flags) {
    if (mInitCheck != OK || index > 0) {
        return NULL;
    }

    return mTrackMeta;
}

status_t WAVExtractor::init() {
    uint8_t header[12];
    if (mDataSource->readAt(
                0, header, sizeof(header)) < (ssize_t)sizeof(header)) {
        return NO_INIT;
    }

    if (memcmp(header, "RIFF", 4) || memcmp(&header[8], "WAVE", 4)) {
        return NO_INIT;
    }

    size_t totalSize = U32_LE_AT(&header[4]);

    off_t offset = 12;
    size_t remainingSize = totalSize;
    while (remainingSize >= 8) {
        uint8_t chunkHeader[8];
        if (mDataSource->readAt(offset, chunkHeader, 8) < 8) {
            return NO_INIT;
        }

        remainingSize -= 8;
        offset += 8;

        uint32_t chunkSize = U32_LE_AT(&chunkHeader[4]);

        if (chunkSize > remainingSize) {
            return NO_INIT;
        }

        if (!memcmp(chunkHeader, "fmt ", 4)) {
            if (chunkSize < 16) {
                return NO_INIT;
            }

            uint8_t formatSpec[16];
            if (mDataSource->readAt(offset, formatSpec, 16) < 16) {
                return NO_INIT;
            }

            uint16_t format = U16_LE_AT(formatSpec);
            if (format != WAVE_FORMAT_PCM) {
                return ERROR_UNSUPPORTED;
            }

            mNumChannels = U16_LE_AT(&formatSpec[2]);
            if (mNumChannels != 1 && mNumChannels != 2) {
                return ERROR_UNSUPPORTED;
            }

            mSampleRate = U32_LE_AT(&formatSpec[4]);

            if (mSampleRate == 0) {
                return ERROR_MALFORMED;
            }

            mBitsPerSample = U16_LE_AT(&formatSpec[14]);

            if (mBitsPerSample != 8 && mBitsPerSample != 16
                && mBitsPerSample != 24) {
                return ERROR_UNSUPPORTED;
            }

            mValidFormat = true;
        } else if (!memcmp(chunkHeader, "data", 4)) {
            if (mValidFormat) {
                mDataOffset = offset;
                mDataSize = chunkSize;

                mTrackMeta = new MetaData;
                mTrackMeta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_RAW);
                mTrackMeta->setInt32(kKeyChannelCount, mNumChannels);
                mTrackMeta->setInt32(kKeySampleRate, mSampleRate);

                size_t bytesPerSample = mBitsPerSample >> 3;

                int64_t durationUs =
                    1000000LL * (mDataSize / (mNumChannels * bytesPerSample))
                        / mSampleRate;

                mTrackMeta->setInt64(kKeyDuration, durationUs);

                return OK;
            }
        }

        offset += chunkSize;
    }

    return NO_INIT;
}

const size_t WAVSource::kMaxFrameSize = 32768;

WAVSource::WAVSource(
        const sp<DataSource> &dataSource,
        const sp<MetaData> &meta,
        int32_t bitsPerSample,
        off_t offset, size_t size)
    : mDataSource(dataSource),
      mMeta(meta),
      mSampleRate(0),
      mNumChannels(0),
      mBitsPerSample(bitsPerSample),
      mOffset(offset),
      mSize(size),
      mStarted(false),
      mGroup(NULL) {
    CHECK(mMeta->findInt32(kKeySampleRate, &mSampleRate));
    CHECK(mMeta->findInt32(kKeyChannelCount, &mNumChannels));
}

WAVSource::~WAVSource() {
    if (mStarted) {
        stop();
    }
}

status_t WAVSource::start(MetaData *params) {
    LOGV("WAVSource::start");

    CHECK(!mStarted);

    mGroup = new MediaBufferGroup;
    mGroup->add_buffer(new MediaBuffer(kMaxFrameSize));

    if (mBitsPerSample == 8) {
        // As a temporary buffer for 8->16 bit conversion.
        mGroup->add_buffer(new MediaBuffer(kMaxFrameSize));
    }

    mCurrentPos = mOffset;

    mStarted = true;

    return OK;
}

status_t WAVSource::stop() {
    LOGV("WAVSource::stop");

    CHECK(mStarted);

    delete mGroup;
    mGroup = NULL;

    mStarted = false;

    return OK;
}

sp<MetaData> WAVSource::getFormat() {
    LOGV("WAVSource::getFormat");

    return mMeta;
}

status_t WAVSource::read(
        MediaBuffer **out, const ReadOptions *options) {
    *out = NULL;

    int64_t seekTimeUs;
    if (options != NULL && options->getSeekTo(&seekTimeUs)) {
        int64_t pos = (seekTimeUs * mSampleRate) / 1000000 * mNumChannels * 2;
        if (pos > mSize) {
            pos = mSize;
        }
        mCurrentPos = pos + mOffset;
    }

    MediaBuffer *buffer;
    status_t err = mGroup->acquire_buffer(&buffer);
    if (err != OK) {
        return err;
    }

    ssize_t n = mDataSource->readAt(
            mCurrentPos, buffer->data(),
            mBitsPerSample == 8 ? kMaxFrameSize / 2 : kMaxFrameSize);

    if (n <= 0) {
        buffer->release();
        buffer = NULL;

        return ERROR_END_OF_STREAM;
    }

    mCurrentPos += n;

    buffer->set_range(0, n);

    if (mBitsPerSample == 8) {
        // Convert 8-bit unsigned samples to 16-bit signed.

        MediaBuffer *tmp;
        CHECK_EQ(mGroup->acquire_buffer(&tmp), OK);

        // The new buffer holds the sample number of samples, but each
        // one is 2 bytes wide.
        tmp->set_range(0, 2 * n);

        int16_t *dst = (int16_t *)tmp->data();
        const uint8_t *src = (const uint8_t *)buffer->data();
        while (n-- > 0) {
            *dst++ = ((int16_t)(*src) - 128) * 256;
            ++src;
        }

        buffer->release();
        buffer = tmp;
    } else if (mBitsPerSample == 24) {
        // Convert 24-bit signed samples to 16-bit signed.

        const uint8_t *src =
            (const uint8_t *)buffer->data() + buffer->range_offset();
        int16_t *dst = (int16_t *)src;

        size_t numSamples = buffer->range_length() / 3;
        for (size_t i = 0; i < numSamples; ++i) {
            int32_t x = (int32_t)(src[0] | src[1] << 8 | src[2] << 16);
            x = (x << 8) >> 8;  // sign extension

            x = x >> 8;
            *dst++ = (int16_t)x;
            src += 3;
        }

        buffer->set_range(buffer->range_offset(), 2 * numSamples);
    }

    size_t bytesPerSample = mBitsPerSample >> 3;

    buffer->meta_data()->setInt64(
            kKeyTime,
            1000000LL * (mCurrentPos - mOffset)
                / (mNumChannels * bytesPerSample) / mSampleRate);


    *out = buffer;

    return OK;
}

////////////////////////////////////////////////////////////////////////////////

bool SniffWAV(
        const sp<DataSource> &source, String8 *mimeType, float *confidence) {
    char header[12];
    if (source->readAt(0, header, sizeof(header)) < (ssize_t)sizeof(header)) {
        return false;
    }

    if (memcmp(header, "RIFF", 4) || memcmp(&header[8], "WAVE", 4)) {
        return false;
    }

    *mimeType = MEDIA_MIMETYPE_CONTAINER_WAV;
    *confidence = 0.3f;

    return true;
}

}  // namespace android