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
24namespace android {
25
26LibsndfileSource::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
35LibsndfileSource::~LibsndfileSource()
36{
37    // do not close mSndfile; we don't own it
38}
39
40ssize_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
46ssize_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