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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "LibsndfileSource"
//#define LOG_NDEBUG 0
#include <utils/Errors.h>
#include <utils/Log.h>
#include <media/nbaio/LibsndfileSource.h>
namespace android {
LibsndfileSource::LibsndfileSource(SNDFILE *sndfile, const SF_INFO &sfinfo, bool loop) :
NBAIO_Source(Format_from_SR_C(sfinfo.samplerate, sfinfo.channels)),
mSndfile(sndfile),
mEstimatedFramesUntilEOF(sfinfo.frames),
mLooping(loop && sfinfo.seekable),
mReadAnyFramesThisLoopCycle(false)
{
}
LibsndfileSource::~LibsndfileSource()
{
// do not close mSndfile; we don't own it
}
ssize_t LibsndfileSource::availableToRead()
{
// after we reach the presumed EOF, report infinity just in case there's actually more
return !mLooping && mEstimatedFramesUntilEOF > 0 ? mEstimatedFramesUntilEOF : SSIZE_MAX;
}
ssize_t LibsndfileSource::read(void *buffer, size_t count)
{
if (!mNegotiated) {
return (ssize_t) NEGOTIATE;
}
if (mSndfile == NULL) {
return (ssize_t) NO_INIT;
}
sf_count_t actual = sf_readf_short(mSndfile, (short *) buffer, (sf_count_t) count);
// Detect EOF by zero frames read, not by mFramesUntilEOF as it could be inaccurate
if (actual == 0) {
if (mLooping) {
if (mReadAnyFramesThisLoopCycle) {
(void) sf_seek(mSndfile, (sf_count_t) 0, SEEK_SET);
mReadAnyFramesThisLoopCycle = false;
} else {
// We didn't read any frames during the current loop cycle, so disable
// further looping to prevent the caller from busy waiting at read().
// This is especially important when looping an empty file.
mLooping = false;
}
}
} else {
mFramesRead += actual;
if (actual >= mEstimatedFramesUntilEOF) {
mEstimatedFramesUntilEOF = 0;
} else {
mEstimatedFramesUntilEOF -= actual;
}
mReadAnyFramesThisLoopCycle = true;
}
return actual;
}
} // namespace android
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