C++ CAStreamBasicDescription::BytesToFrames方法代码示例

//.........这里部分代码省略.........
            // we are always going to be able to resume conversion after an interruption
            
            if (kAudioConverterErr_PropertyNotSupported == error) {
                printf("kAudioConverterPropertyCanResumeFromInterruption property not supported!\n");
            } else {
                printf("AudioConverterGetProperty kAudioConverterPropertyCanResumeFromInterruption result %ld\n", error);
            }
            
            error = noErr;
        }
        
        // set up buffers
        UInt32 bufferByteSize = 32768;
        char srcBuffer[bufferByteSize];
        
        // keep track of the source file offset so we know where to reset the source for
        // reading if interrupted and input was not consumed by the audio converter
        SInt64 sourceFrameOffset = 0;
        
        //***** do the read and write - the conversion is done on and by the write call *****//
        printf("Converting...\n");
        while (1) {
        
            AudioBufferList fillBufList;
            fillBufList.mNumberBuffers = 1;
            fillBufList.mBuffers[0].mNumberChannels = clientFormat.NumberChannels();
            fillBufList.mBuffers[0].mDataByteSize = bufferByteSize;
            fillBufList.mBuffers[0].mData = srcBuffer;
                
            // client format is always linear PCM - so here we determine how many frames of lpcm
            // we can read/write given our buffer size
            UInt32 numFrames;
            if (clientFormat.mBytesPerFrame > 0) // rids bogus analyzer div by zero warning mBytesPerFrame can't be 0 and is protected by an Assert
                numFrames = clientFormat.BytesToFrames(bufferByteSize); // (bufferByteSize / clientFormat.mBytesPerFrame);

            XThrowIfError(ExtAudioFileRead(sourceFile, &numFrames, &fillBufList), "ExtAudioFileRead failed!");	
            if (!numFrames) {
                // this is our termination condition
                error = noErr;
                break;
            }
            sourceFrameOffset += numFrames;
            
            // this will block if we're interrupted
            Boolean wasInterrupted = ThreadStatePausedCheck();
            
            if ((error || wasInterrupted) && (false == canResumeFromInterruption)) {
                // this is our interruption termination condition
                // an interruption has occured but the audio converter cannot continue
                error = kMyAudioConverterErr_CannotResumeFromInterruptionError;
                break;
            }

            error = ExtAudioFileWrite(destinationFile, numFrames, &fillBufList);
            // if interrupted in the process of the write call, we must handle the errors appropriately
            if (error) {
                if (kExtAudioFileError_CodecUnavailableInputConsumed == error) {
                
                    printf("ExtAudioFileWrite kExtAudioFileError_CodecUnavailableInputConsumed error %ld\n", error);
                    
                    /*
                        Returned when ExtAudioFileWrite was interrupted. You must stop calling
                        ExtAudioFileWrite. If the underlying audio converter can resume after an
                        interruption (see kAudioConverterPropertyCanResumeFromInterruption), you must
                        wait for an EndInterruption notification from AudioSession, then activate the session
                        before resuming. In this situation, the buffer you provided to ExtAudioFileWrite was successfully