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      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 
     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 
     35 LibsndfileSource::~LibsndfileSource()
     36 {
     37     // do not close mSndfile; we don't own it
     38 }
     39 
     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 
     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