WAVExtractor.cpp revision 5a1c3529e4fa2f8a11054181294e0ce79fff8dd3 
1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17//#define LOG_NDEBUG 0
18#define LOG_TAG "WAVExtractor"
19#include <utils/Log.h>
20
21#include "include/WAVExtractor.h"
22
23#include <media/stagefright/DataSource.h>
24#include <media/stagefright/MediaBufferGroup.h>
25#include <media/stagefright/MediaDebug.h>
26#include <media/stagefright/MediaDefs.h>
27#include <media/stagefright/MediaErrors.h>
28#include <media/stagefright/MediaSource.h>
29#include <media/stagefright/MetaData.h>
30#include <utils/String8.h>
31
32namespace android {
33
34enum {
35    WAVE_FORMAT_PCM = 1,
36    WAVE_FORMAT_ALAW = 6,
37    WAVE_FORMAT_MULAW = 7,
38};
39
40static uint32_t U32_LE_AT(const uint8_t *ptr) {
41    return ptr[3] << 24 | ptr[2] << 16 | ptr[1] << 8 | ptr[0];
42}
43
44static uint16_t U16_LE_AT(const uint8_t *ptr) {
45    return ptr[1] << 8 | ptr[0];
46}
47
48struct WAVSource : public MediaSource {
49    WAVSource(
50            const sp<DataSource> &dataSource,
51            const sp<MetaData> &meta,
52            uint16_t waveFormat,
53            int32_t bitsPerSample,
54            off_t offset, size_t size);
55
56    virtual status_t start(MetaData *params = NULL);
57    virtual status_t stop();
58    virtual sp<MetaData> getFormat();
59
60    virtual status_t read(
61            MediaBuffer **buffer, const ReadOptions *options = NULL);
62
63protected:
64    virtual ~WAVSource();
65
66private:
67    static const size_t kMaxFrameSize;
68
69    sp<DataSource> mDataSource;
70    sp<MetaData> mMeta;
71    uint16_t mWaveFormat;
72    int32_t mSampleRate;
73    int32_t mNumChannels;
74    int32_t mBitsPerSample;
75    off_t mOffset;
76    size_t mSize;
77    bool mStarted;
78    MediaBufferGroup *mGroup;
79    off_t mCurrentPos;
80
81    WAVSource(const WAVSource &);
82    WAVSource &operator=(const WAVSource &);
83};
84
85WAVExtractor::WAVExtractor(const sp<DataSource> &source)
86    : mDataSource(source),
87      mValidFormat(false) {
88    mInitCheck = init();
89}
90
91WAVExtractor::~WAVExtractor() {
92}
93
94sp<MetaData> WAVExtractor::getMetaData() {
95    sp<MetaData> meta = new MetaData;
96
97    if (mInitCheck != OK) {
98        return meta;
99    }
100
101    meta->setCString(kKeyMIMEType, "audio/x-wav");
102
103    return meta;
104}
105
106size_t WAVExtractor::countTracks() {
107    return mInitCheck == OK ? 1 : 0;
108}
109
110sp<MediaSource> WAVExtractor::getTrack(size_t index) {
111    if (mInitCheck != OK || index > 0) {
112        return NULL;
113    }
114
115    return new WAVSource(
116            mDataSource, mTrackMeta,
117            mWaveFormat, mBitsPerSample, mDataOffset, mDataSize);
118}
119
120sp<MetaData> WAVExtractor::getTrackMetaData(
121        size_t index, uint32_t flags) {
122    if (mInitCheck != OK || index > 0) {
123        return NULL;
124    }
125
126    return mTrackMeta;
127}
128
129status_t WAVExtractor::init() {
130    uint8_t header[12];
131    if (mDataSource->readAt(
132                0, header, sizeof(header)) < (ssize_t)sizeof(header)) {
133        return NO_INIT;
134    }
135
136    if (memcmp(header, "RIFF", 4) || memcmp(&header[8], "WAVE", 4)) {
137        return NO_INIT;
138    }
139
140    size_t totalSize = U32_LE_AT(&header[4]);
141
142    off_t offset = 12;
143    size_t remainingSize = totalSize;
144    while (remainingSize >= 8) {
145        uint8_t chunkHeader[8];
146        if (mDataSource->readAt(offset, chunkHeader, 8) < 8) {
147            return NO_INIT;
148        }
149
150        remainingSize -= 8;
151        offset += 8;
152
153        uint32_t chunkSize = U32_LE_AT(&chunkHeader[4]);
154
155        if (chunkSize > remainingSize) {
156            return NO_INIT;
157        }
158
159        if (!memcmp(chunkHeader, "fmt ", 4)) {
160            if (chunkSize < 16) {
161                return NO_INIT;
162            }
163
164            uint8_t formatSpec[16];
165            if (mDataSource->readAt(offset, formatSpec, 16) < 16) {
166                return NO_INIT;
167            }
168
169            mWaveFormat = U16_LE_AT(formatSpec);
170            if (mWaveFormat != WAVE_FORMAT_PCM
171                    && mWaveFormat != WAVE_FORMAT_ALAW
172                    && mWaveFormat != WAVE_FORMAT_MULAW) {
173                return ERROR_UNSUPPORTED;
174            }
175
176            mNumChannels = U16_LE_AT(&formatSpec[2]);
177            if (mNumChannels != 1 && mNumChannels != 2) {
178                return ERROR_UNSUPPORTED;
179            }
180
181            mSampleRate = U32_LE_AT(&formatSpec[4]);
182
183            if (mSampleRate == 0) {
184                return ERROR_MALFORMED;
185            }
186
187            mBitsPerSample = U16_LE_AT(&formatSpec[14]);
188
189            if (mWaveFormat == WAVE_FORMAT_PCM) {
190                if (mBitsPerSample != 8 && mBitsPerSample != 16
191                    && mBitsPerSample != 24) {
192                    return ERROR_UNSUPPORTED;
193                }
194            } else {
195                CHECK(mWaveFormat == WAVE_FORMAT_MULAW
196                        || mWaveFormat == WAVE_FORMAT_ALAW);
197                if (mBitsPerSample != 8) {
198                    return ERROR_UNSUPPORTED;
199                }
200            }
201
202            mValidFormat = true;
203        } else if (!memcmp(chunkHeader, "data", 4)) {
204            if (mValidFormat) {
205                mDataOffset = offset;
206                mDataSize = chunkSize;
207
208                mTrackMeta = new MetaData;
209
210                switch (mWaveFormat) {
211                    case WAVE_FORMAT_PCM:
212                        mTrackMeta->setCString(
213                                kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_RAW);
214                        break;
215                    case WAVE_FORMAT_ALAW:
216                        mTrackMeta->setCString(
217                                kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_G711_ALAW);
218                        break;
219                    default:
220                        CHECK_EQ(mWaveFormat, WAVE_FORMAT_MULAW);
221                        mTrackMeta->setCString(
222                                kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_G711_MLAW);
223                        break;
224                }
225
226                mTrackMeta->setInt32(kKeyChannelCount, mNumChannels);
227                mTrackMeta->setInt32(kKeySampleRate, mSampleRate);
228
229                size_t bytesPerSample = mBitsPerSample >> 3;
230
231                int64_t durationUs =
232                    1000000LL * (mDataSize / (mNumChannels * bytesPerSample))
233                        / mSampleRate;
234
235                mTrackMeta->setInt64(kKeyDuration, durationUs);
236
237                return OK;
238            }
239        }
240
241        offset += chunkSize;
242    }
243
244    return NO_INIT;
245}
246
247const size_t WAVSource::kMaxFrameSize = 32768;
248
249WAVSource::WAVSource(
250        const sp<DataSource> &dataSource,
251        const sp<MetaData> &meta,
252        uint16_t waveFormat,
253        int32_t bitsPerSample,
254        off_t offset, size_t size)
255    : mDataSource(dataSource),
256      mMeta(meta),
257      mWaveFormat(waveFormat),
258      mSampleRate(0),
259      mNumChannels(0),
260      mBitsPerSample(bitsPerSample),
261      mOffset(offset),
262      mSize(size),
263      mStarted(false),
264      mGroup(NULL) {
265    CHECK(mMeta->findInt32(kKeySampleRate, &mSampleRate));
266    CHECK(mMeta->findInt32(kKeyChannelCount, &mNumChannels));
267}
268
269WAVSource::~WAVSource() {
270    if (mStarted) {
271        stop();
272    }
273}
274
275status_t WAVSource::start(MetaData *params) {
276    LOGV("WAVSource::start");
277
278    CHECK(!mStarted);
279
280    mGroup = new MediaBufferGroup;
281    mGroup->add_buffer(new MediaBuffer(kMaxFrameSize));
282
283    if (mBitsPerSample == 8) {
284        // As a temporary buffer for 8->16 bit conversion.
285        mGroup->add_buffer(new MediaBuffer(kMaxFrameSize));
286    }
287
288    mCurrentPos = mOffset;
289
290    mStarted = true;
291
292    return OK;
293}
294
295status_t WAVSource::stop() {
296    LOGV("WAVSource::stop");
297
298    CHECK(mStarted);
299
300    delete mGroup;
301    mGroup = NULL;
302
303    mStarted = false;
304
305    return OK;
306}
307
308sp<MetaData> WAVSource::getFormat() {
309    LOGV("WAVSource::getFormat");
310
311    return mMeta;
312}
313
314status_t WAVSource::read(
315        MediaBuffer **out, const ReadOptions *options) {
316    *out = NULL;
317
318    int64_t seekTimeUs;
319    ReadOptions::SeekMode mode;
320    if (options != NULL && options->getSeekTo(&seekTimeUs, &mode)) {
321        int64_t pos = (seekTimeUs * mSampleRate) / 1000000 * mNumChannels * 2;
322        if (pos > mSize) {
323            pos = mSize;
324        }
325        mCurrentPos = pos + mOffset;
326    }
327
328    MediaBuffer *buffer;
329    status_t err = mGroup->acquire_buffer(&buffer);
330    if (err != OK) {
331        return err;
332    }
333
334    ssize_t n = mDataSource->readAt(
335            mCurrentPos, buffer->data(),
336            mBitsPerSample == 8 ? kMaxFrameSize / 2 : kMaxFrameSize);
337
338    if (n <= 0) {
339        buffer->release();
340        buffer = NULL;
341
342        return ERROR_END_OF_STREAM;
343    }
344
345    mCurrentPos += n;
346
347    buffer->set_range(0, n);
348
349    if (mWaveFormat == WAVE_FORMAT_PCM) {
350        if (mBitsPerSample == 8) {
351            // Convert 8-bit unsigned samples to 16-bit signed.
352
353            MediaBuffer *tmp;
354            CHECK_EQ(mGroup->acquire_buffer(&tmp), OK);
355
356            // The new buffer holds the sample number of samples, but each
357            // one is 2 bytes wide.
358            tmp->set_range(0, 2 * n);
359
360            int16_t *dst = (int16_t *)tmp->data();
361            const uint8_t *src = (const uint8_t *)buffer->data();
362            while (n-- > 0) {
363                *dst++ = ((int16_t)(*src) - 128) * 256;
364                ++src;
365            }
366
367            buffer->release();
368            buffer = tmp;
369        } else if (mBitsPerSample == 24) {
370            // Convert 24-bit signed samples to 16-bit signed.
371
372            const uint8_t *src =
373                (const uint8_t *)buffer->data() + buffer->range_offset();
374            int16_t *dst = (int16_t *)src;
375
376            size_t numSamples = buffer->range_length() / 3;
377            for (size_t i = 0; i < numSamples; ++i) {
378                int32_t x = (int32_t)(src[0] | src[1] << 8 | src[2] << 16);
379                x = (x << 8) >> 8;  // sign extension
380
381                x = x >> 8;
382                *dst++ = (int16_t)x;
383                src += 3;
384            }
385
386            buffer->set_range(buffer->range_offset(), 2 * numSamples);
387        }
388    }
389
390    size_t bytesPerSample = mBitsPerSample >> 3;
391
392    buffer->meta_data()->setInt64(
393            kKeyTime,
394            1000000LL * (mCurrentPos - mOffset)
395                / (mNumChannels * bytesPerSample) / mSampleRate);
396
397    buffer->meta_data()->setInt32(kKeyIsSyncFrame, 1);
398
399    *out = buffer;
400
401    return OK;
402}
403
404////////////////////////////////////////////////////////////////////////////////
405
406bool SniffWAV(
407        const sp<DataSource> &source, String8 *mimeType, float *confidence,
408        sp<AMessage> *) {
409    char header[12];
410    if (source->readAt(0, header, sizeof(header)) < (ssize_t)sizeof(header)) {
411        return false;
412    }
413
414    if (memcmp(header, "RIFF", 4) || memcmp(&header[8], "WAVE", 4)) {
415        return false;
416    }
417
418    *mimeType = MEDIA_MIMETYPE_CONTAINER_WAV;
419    *confidence = 0.3f;
420
421    return true;
422}
423
424}  // namespace android
425
426