ASessionDescription.cpp revision f4eadb67ba9130b583b8f2f192276b53fa3d50bc 
1/*
2 * Copyright (C) 2010 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 "ASessionDescription"
19#include <utils/Log.h>
20
21#include "ASessionDescription.h"
22
23#include <media/stagefright/foundation/ADebug.h>
24#include <media/stagefright/foundation/AString.h>
25
26#include <stdlib.h>
27
28namespace android {
29
30ASessionDescription::ASessionDescription()
31    : mIsValid(false) {
32}
33
34ASessionDescription::~ASessionDescription() {
35}
36
37bool ASessionDescription::setTo(const void *data, size_t size) {
38    mIsValid = parse(data, size);
39
40    if (!mIsValid) {
41        mTracks.clear();
42        mFormats.clear();
43    }
44
45    return mIsValid;
46}
47
48bool ASessionDescription::parse(const void *data, size_t size) {
49    mTracks.clear();
50    mFormats.clear();
51
52    mTracks.push(Attribs());
53    mFormats.push(AString("[root]"));
54
55    AString desc((const char *)data, size);
56
57    size_t i = 0;
58    for (;;) {
59        ssize_t eolPos = desc.find("\n", i);
60
61        if (eolPos < 0) {
62            break;
63        }
64
65        AString line;
66        if ((size_t)eolPos > i && desc.c_str()[eolPos - 1] == '\r') {
67            // We accept both '\n' and '\r\n' line endings, if it's
68            // the latter, strip the '\r' as well.
69            line.setTo(desc, i, eolPos - i - 1);
70        } else {
71            line.setTo(desc, i, eolPos - i);
72        }
73
74        if (line.empty()) {
75            i = eolPos + 1;
76            continue;
77        }
78
79        if (line.size() < 2 || line.c_str()[1] != '=') {
80            return false;
81        }
82
83        ALOGI("%s", line.c_str());
84
85        switch (line.c_str()[0]) {
86            case 'v':
87            {
88                if (strcmp(line.c_str(), "v=0")) {
89                    return false;
90                }
91                break;
92            }
93
94            case 'a':
95            case 'b':
96            {
97                AString key, value;
98
99                ssize_t colonPos = line.find(":", 2);
100                if (colonPos < 0) {
101                    key = line;
102                } else {
103                    key.setTo(line, 0, colonPos);
104
105                    if (key == "a=fmtp" || key == "a=rtpmap"
106                            || key == "a=framesize") {
107                        ssize_t spacePos = line.find(" ", colonPos + 1);
108                        if (spacePos < 0) {
109                            return false;
110                        }
111
112                        key.setTo(line, 0, spacePos);
113
114                        colonPos = spacePos;
115                    }
116
117                    value.setTo(line, colonPos + 1, line.size() - colonPos - 1);
118                }
119
120                key.trim();
121                value.trim();
122
123                ALOGV("adding '%s' => '%s'", key.c_str(), value.c_str());
124
125                mTracks.editItemAt(mTracks.size() - 1).add(key, value);
126                break;
127            }
128
129            case 'm':
130            {
131                ALOGV("new section '%s'",
132                     AString(line, 2, line.size() - 2).c_str());
133
134                mTracks.push(Attribs());
135                mFormats.push(AString(line, 2, line.size() - 2));
136                break;
137            }
138
139            default:
140            {
141                AString key, value;
142
143                ssize_t equalPos = line.find("=");
144
145                key = AString(line, 0, equalPos + 1);
146                value = AString(line, equalPos + 1, line.size() - equalPos - 1);
147
148                key.trim();
149                value.trim();
150
151                ALOGV("adding '%s' => '%s'", key.c_str(), value.c_str());
152
153                mTracks.editItemAt(mTracks.size() - 1).add(key, value);
154                break;
155            }
156        }
157
158        i = eolPos + 1;
159    }
160
161    return true;
162}
163
164bool ASessionDescription::isValid() const {
165    return mIsValid;
166}
167
168size_t ASessionDescription::countTracks() const {
169    return mTracks.size();
170}
171
172void ASessionDescription::getFormat(size_t index, AString *value) const {
173    CHECK_GE(index, 0u);
174    CHECK_LT(index, mTracks.size());
175
176    *value = mFormats.itemAt(index);
177}
178
179bool ASessionDescription::findAttribute(
180        size_t index, const char *key, AString *value) const {
181    CHECK_GE(index, 0u);
182    CHECK_LT(index, mTracks.size());
183
184    value->clear();
185
186    const Attribs &track = mTracks.itemAt(index);
187    ssize_t i = track.indexOfKey(AString(key));
188
189    if (i < 0) {
190        return false;
191    }
192
193    *value = track.valueAt(i);
194
195    return true;
196}
197
198void ASessionDescription::getFormatType(
199        size_t index, unsigned long *PT,
200        AString *desc, AString *params) const {
201    AString format;
202    getFormat(index, &format);
203
204    const char *lastSpacePos = strrchr(format.c_str(), ' ');
205    CHECK(lastSpacePos != NULL);
206
207    char *end;
208    unsigned long x = strtoul(lastSpacePos + 1, &end, 10);
209    CHECK_GT(end, lastSpacePos + 1);
210    CHECK_EQ(*end, '\0');
211
212    *PT = x;
213
214    char key[20];
215    sprintf(key, "a=rtpmap:%lu", x);
216
217    CHECK(findAttribute(index, key, desc));
218
219    sprintf(key, "a=fmtp:%lu", x);
220    if (!findAttribute(index, key, params)) {
221        params->clear();
222    }
223}
224
225bool ASessionDescription::getDimensions(
226        size_t index, unsigned long PT,
227        int32_t *width, int32_t *height) const {
228    *width = 0;
229    *height = 0;
230
231    char key[20];
232    sprintf(key, "a=framesize:%lu", PT);
233    AString value;
234    if (!findAttribute(index, key, &value)) {
235        return false;
236    }
237
238    const char *s = value.c_str();
239    char *end;
240    *width = strtoul(s, &end, 10);
241    CHECK_GT(end, s);
242    CHECK_EQ(*end, '-');
243
244    s = end + 1;
245    *height = strtoul(s, &end, 10);
246    CHECK_GT(end, s);
247    CHECK_EQ(*end, '\0');
248
249    return true;
250}
251
252bool ASessionDescription::getDurationUs(int64_t *durationUs) const {
253    *durationUs = 0;
254
255    CHECK(mIsValid);
256
257    AString value;
258    if (!findAttribute(0, "a=range", &value)) {
259        return false;
260    }
261
262    if (strncmp(value.c_str(), "npt=", 4)) {
263        return false;
264    }
265
266    float from, to;
267    if (!parseNTPRange(value.c_str() + 4, &from, &to)) {
268        return false;
269    }
270
271    *durationUs = (int64_t)((to - from) * 1E6);
272
273    return true;
274}
275
276// static
277void ASessionDescription::ParseFormatDesc(
278        const char *desc, int32_t *timescale, int32_t *numChannels) {
279    const char *slash1 = strchr(desc, '/');
280    CHECK(slash1 != NULL);
281
282    const char *s = slash1 + 1;
283    char *end;
284    unsigned long x = strtoul(s, &end, 10);
285    CHECK_GT(end, s);
286    CHECK(*end == '\0' || *end == '/');
287
288    *timescale = x;
289    *numChannels = 1;
290
291    if (*end == '/') {
292        s = end + 1;
293        unsigned long x = strtoul(s, &end, 10);
294        CHECK_GT(end, s);
295        CHECK_EQ(*end, '\0');
296
297        *numChannels = x;
298    }
299}
300
301// static
302bool ASessionDescription::parseNTPRange(
303        const char *s, float *npt1, float *npt2) {
304    if (s[0] == '-') {
305        return false;  // no start time available.
306    }
307
308    if (!strncmp("now", s, 3)) {
309        return false;  // no absolute start time available
310    }
311
312    char *end;
313    *npt1 = strtof(s, &end);
314
315    if (end == s || *end != '-') {
316        // Failed to parse float or trailing "dash".
317        return false;
318    }
319
320    s = end + 1;  // skip the dash.
321
322    if (*s == '\0') {
323        *npt2 = FLT_MAX;  // open ended.
324        return true;
325    }
326
327    if (!strncmp("now", s, 3)) {
328        return false;  // no absolute end time available
329    }
330
331    *npt2 = strtof(s, &end);
332
333    if (end == s || *end != '\0') {
334        return false;
335    }
336
337    return *npt2 > *npt1;
338}
339
340}  // namespace android
341
342