AMRExtractor.cpp revision db43b34c3428e480f8c4c66e7e88f4001f37f91e 
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 "AMRExtractor"
19#include <utils/Log.h>
20
21#include "include/AMRExtractor.h"
22
23#include <media/stagefright/foundation/ADebug.h>
24#include <media/stagefright/DataSource.h>
25#include <media/stagefright/MediaBufferGroup.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
34class AMRSource : public MediaSource {
35public:
36    AMRSource(const sp<DataSource> &source,
37              const sp<MetaData> &meta,
38              bool isWide,
39              const off64_t *offset_table,
40              size_t offset_table_length);
41
42    virtual status_t start(MetaData *params = NULL);
43    virtual status_t stop();
44
45    virtual sp<MetaData> getFormat();
46
47    virtual status_t read(
48            MediaBuffer **buffer, const ReadOptions *options = NULL);
49
50protected:
51    virtual ~AMRSource();
52
53private:
54    sp<DataSource> mDataSource;
55    sp<MetaData> mMeta;
56    bool mIsWide;
57
58    off64_t mOffset;
59    int64_t mCurrentTimeUs;
60    bool mStarted;
61    MediaBufferGroup *mGroup;
62
63    off64_t mOffsetTable[OFFSET_TABLE_LEN];
64    size_t mOffsetTableLength;
65
66    AMRSource(const AMRSource &);
67    AMRSource &operator=(const AMRSource &);
68};
69
70////////////////////////////////////////////////////////////////////////////////
71
72static size_t getFrameSize(bool isWide, unsigned FT) {
73    static const size_t kFrameSizeNB[16] = {
74        95, 103, 118, 134, 148, 159, 204, 244,
75        39, 43, 38, 37, // SID
76        0, 0, 0, // future use
77        0 // no data
78    };
79    static const size_t kFrameSizeWB[16] = {
80        132, 177, 253, 285, 317, 365, 397, 461, 477,
81        40, // SID
82        0, 0, 0, 0, // future use
83        0, // speech lost
84        0 // no data
85    };
86
87    if (FT > 15 || (isWide && FT > 9 && FT < 14) || (!isWide && FT > 11 && FT < 15)) {
88        ALOGE("illegal AMR frame type %d", FT);
89        return 0;
90    }
91
92    size_t frameSize = isWide ? kFrameSizeWB[FT] : kFrameSizeNB[FT];
93
94    // Round up bits to bytes and add 1 for the header byte.
95    frameSize = (frameSize + 7) / 8 + 1;
96
97    return frameSize;
98}
99
100static status_t getFrameSizeByOffset(const sp<DataSource> &source,
101        off64_t offset, bool isWide, size_t *frameSize) {
102    uint8_t header;
103    if (source->readAt(offset, &header, 1) < 1) {
104        return ERROR_IO;
105    }
106
107    unsigned FT = (header >> 3) & 0x0f;
108
109    *frameSize = getFrameSize(isWide, FT);
110    if (*frameSize == 0) {
111        return ERROR_MALFORMED;
112    }
113    return OK;
114}
115
116AMRExtractor::AMRExtractor(const sp<DataSource> &source)
117    : mDataSource(source),
118      mInitCheck(NO_INIT),
119      mOffsetTableLength(0) {
120    String8 mimeType;
121    float confidence;
122    if (!SniffAMR(mDataSource, &mimeType, &confidence, NULL)) {
123        return;
124    }
125
126    mIsWide = (mimeType == MEDIA_MIMETYPE_AUDIO_AMR_WB);
127
128    mMeta = new MetaData;
129    mMeta->setCString(
130            kKeyMIMEType, mIsWide ? MEDIA_MIMETYPE_AUDIO_AMR_WB
131                                  : MEDIA_MIMETYPE_AUDIO_AMR_NB);
132
133    mMeta->setInt32(kKeyChannelCount, 1);
134    mMeta->setInt32(kKeySampleRate, mIsWide ? 16000 : 8000);
135
136    off64_t offset = mIsWide ? 9 : 6;
137    off64_t streamSize;
138    size_t frameSize, numFrames = 0;
139    int64_t duration = 0;
140
141    if (mDataSource->getSize(&streamSize) == OK) {
142         while (offset < streamSize) {
143            if (getFrameSizeByOffset(source, offset, mIsWide, &frameSize) != OK) {
144                return;
145            }
146
147            if ((numFrames % 50 == 0) && (numFrames / 50 < OFFSET_TABLE_LEN)) {
148                CHECK_EQ(mOffsetTableLength, numFrames / 50);
149                mOffsetTable[mOffsetTableLength] = offset - (mIsWide ? 9: 6);
150                mOffsetTableLength ++;
151            }
152
153            offset += frameSize;
154            duration += 20000;  // Each frame is 20ms
155            numFrames ++;
156        }
157
158        mMeta->setInt64(kKeyDuration, duration);
159    }
160
161    mInitCheck = OK;
162}
163
164AMRExtractor::~AMRExtractor() {
165}
166
167sp<MetaData> AMRExtractor::getMetaData() {
168    sp<MetaData> meta = new MetaData;
169
170    if (mInitCheck != OK) {
171        return meta;
172    }
173
174    meta->setCString(kKeyMIMEType, mIsWide ? "audio/amr-wb" : "audio/amr");
175
176    return meta;
177}
178
179size_t AMRExtractor::countTracks() {
180    return mInitCheck == OK ? 1 : 0;
181}
182
183sp<MediaSource> AMRExtractor::getTrack(size_t index) {
184    if (mInitCheck != OK || index != 0) {
185        return NULL;
186    }
187
188    return new AMRSource(mDataSource, mMeta, mIsWide,
189            mOffsetTable, mOffsetTableLength);
190}
191
192sp<MetaData> AMRExtractor::getTrackMetaData(size_t index, uint32_t /* flags */) {
193    if (mInitCheck != OK || index != 0) {
194        return NULL;
195    }
196
197    return mMeta;
198}
199
200////////////////////////////////////////////////////////////////////////////////
201
202AMRSource::AMRSource(
203        const sp<DataSource> &source, const sp<MetaData> &meta,
204        bool isWide, const off64_t *offset_table, size_t offset_table_length)
205    : mDataSource(source),
206      mMeta(meta),
207      mIsWide(isWide),
208      mOffset(mIsWide ? 9 : 6),
209      mCurrentTimeUs(0),
210      mStarted(false),
211      mGroup(NULL),
212      mOffsetTableLength(offset_table_length) {
213    if (mOffsetTableLength > 0 && mOffsetTableLength <= OFFSET_TABLE_LEN) {
214        memcpy ((char*)mOffsetTable, (char*)offset_table, sizeof(off64_t) * mOffsetTableLength);
215    }
216}
217
218AMRSource::~AMRSource() {
219    if (mStarted) {
220        stop();
221    }
222}
223
224status_t AMRSource::start(MetaData * /* params */) {
225    CHECK(!mStarted);
226
227    mOffset = mIsWide ? 9 : 6;
228    mCurrentTimeUs = 0;
229    mGroup = new MediaBufferGroup;
230    mGroup->add_buffer(new MediaBuffer(128));
231    mStarted = true;
232
233    return OK;
234}
235
236status_t AMRSource::stop() {
237    CHECK(mStarted);
238
239    delete mGroup;
240    mGroup = NULL;
241
242    mStarted = false;
243    return OK;
244}
245
246sp<MetaData> AMRSource::getFormat() {
247    return mMeta;
248}
249
250status_t AMRSource::read(
251        MediaBuffer **out, const ReadOptions *options) {
252    *out = NULL;
253
254    int64_t seekTimeUs;
255    ReadOptions::SeekMode mode;
256    if (options && options->getSeekTo(&seekTimeUs, &mode)) {
257        size_t size;
258        int64_t seekFrame = seekTimeUs / 20000ll;  // 20ms per frame.
259        mCurrentTimeUs = seekFrame * 20000ll;
260
261        size_t index = seekFrame < 0 ? 0 : seekFrame / 50;
262        if (index >= mOffsetTableLength) {
263            index = mOffsetTableLength - 1;
264        }
265
266        mOffset = mOffsetTable[index] + (mIsWide ? 9 : 6);
267
268        for (size_t i = 0; i< seekFrame - index * 50; i++) {
269            status_t err;
270            if ((err = getFrameSizeByOffset(mDataSource, mOffset,
271                            mIsWide, &size)) != OK) {
272                return err;
273            }
274            mOffset += size;
275        }
276    }
277
278    uint8_t header;
279    ssize_t n = mDataSource->readAt(mOffset, &header, 1);
280
281    if (n < 1) {
282        return ERROR_END_OF_STREAM;
283    }
284
285    if (header & 0x83) {
286        // Padding bits must be 0.
287
288        ALOGE("padding bits must be 0, header is 0x%02x", header);
289
290        return ERROR_MALFORMED;
291    }
292
293    unsigned FT = (header >> 3) & 0x0f;
294
295    size_t frameSize = getFrameSize(mIsWide, FT);
296    if (frameSize == 0) {
297        return ERROR_MALFORMED;
298    }
299
300    MediaBuffer *buffer;
301    status_t err = mGroup->acquire_buffer(&buffer);
302    if (err != OK) {
303        return err;
304    }
305
306    n = mDataSource->readAt(mOffset, buffer->data(), frameSize);
307
308    if (n != (ssize_t)frameSize) {
309        buffer->release();
310        buffer = NULL;
311
312        return ERROR_IO;
313    }
314
315    buffer->set_range(0, frameSize);
316    buffer->meta_data()->setInt64(kKeyTime, mCurrentTimeUs);
317    buffer->meta_data()->setInt32(kKeyIsSyncFrame, 1);
318
319    mOffset += frameSize;
320    mCurrentTimeUs += 20000;  // Each frame is 20ms
321
322    *out = buffer;
323
324    return OK;
325}
326
327////////////////////////////////////////////////////////////////////////////////
328
329bool SniffAMR(
330        const sp<DataSource> &source, String8 *mimeType, float *confidence,
331        sp<AMessage> *) {
332    char header[9];
333
334    if (source->readAt(0, header, sizeof(header)) != sizeof(header)) {
335        return false;
336    }
337
338    if (!memcmp(header, "#!AMR\n", 6)) {
339        *mimeType = MEDIA_MIMETYPE_AUDIO_AMR_NB;
340        *confidence = 0.5;
341
342        return true;
343    } else if (!memcmp(header, "#!AMR-WB\n", 9)) {
344        *mimeType = MEDIA_MIMETYPE_AUDIO_AMR_WB;
345        *confidence = 0.5;
346
347        return true;
348    }
349
350    return false;
351}
352
353}  // namespace android
354