1 /*
2 * Copyright (C) 2012 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_TAG "LibsndfileSource"
18 //#define LOG_NDEBUG 0
19
20 #include <utils/Errors.h>
21 #include <utils/Log.h>
22 #include <media/nbaio/LibsndfileSource.h>
23
24 namespace android {
25
LibsndfileSource(SNDFILE * sndfile,const SF_INFO & sfinfo,bool loop)26 LibsndfileSource::LibsndfileSource(SNDFILE *sndfile, const SF_INFO &sfinfo, bool loop) :
27 NBAIO_Source(Format_from_SR_C(sfinfo.samplerate, sfinfo.channels)),
28 mSndfile(sndfile),
29 mEstimatedFramesUntilEOF(sfinfo.frames),
30 mLooping(loop && sfinfo.seekable),
31 mReadAnyFramesThisLoopCycle(false)
32 {
33 }
34
~LibsndfileSource()35 LibsndfileSource::~LibsndfileSource()
36 {
37 // do not close mSndfile; we don't own it
38 }
39
availableToRead()40 ssize_t LibsndfileSource::availableToRead()
41 {
42 // after we reach the presumed EOF, report infinity just in case there's actually more
43 return !mLooping && mEstimatedFramesUntilEOF > 0 ? mEstimatedFramesUntilEOF : SSIZE_MAX;
44 }
45
read(void * buffer,size_t count)46 ssize_t LibsndfileSource::read(void *buffer, size_t count)
47 {
48 if (!mNegotiated) {
49 return (ssize_t) NEGOTIATE;
50 }
51 if (mSndfile == NULL) {
52 return (ssize_t) NO_INIT;
53 }
54 sf_count_t actual = sf_readf_short(mSndfile, (short *) buffer, (sf_count_t) count);
55 // Detect EOF by zero frames read, not by mFramesUntilEOF as it could be inaccurate
56 if (actual == 0) {
57 if (mLooping) {
58 if (mReadAnyFramesThisLoopCycle) {
59 (void) sf_seek(mSndfile, (sf_count_t) 0, SEEK_SET);
60 mReadAnyFramesThisLoopCycle = false;
61 } else {
62 // We didn't read any frames during the current loop cycle, so disable
63 // further looping to prevent the caller from busy waiting at read().
64 // This is especially important when looping an empty file.
65 mLooping = false;
66 }
67 }
68 } else {
69 mFramesRead += actual;
70 if (actual >= mEstimatedFramesUntilEOF) {
71 mEstimatedFramesUntilEOF = 0;
72 } else {
73 mEstimatedFramesUntilEOF -= actual;
74 }
75 mReadAnyFramesThisLoopCycle = true;
76 }
77 return actual;
78 }
79
80 } // namespace android
81