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#include <string.h>
// these are headers for the ALAC decoder, utilities and endian utilities
#include <alac/ALACBitUtilities.h>
#include <alac/ALACDecoder.h>
#include <alac/EndianPortable.h>
#include "apple_alac.h"
#include "config.h"
typedef struct magicCookie {
ALACSpecificConfig config;
ALACAudioChannelLayout channelLayoutInfo; // seems to be unused
} magicCookie;
magicCookie cookie;
ALACDecoder *theDecoder;
extern "C" int apple_alac_init(int32_t fmtp[12]) {
memset(&cookie, 0, sizeof(magicCookie));
// create a magic cookie for the decoder from the fmtp information. It seems to be in the same
// format as a simple magic cookie
cookie.config.frameLength = Swap32NtoB(352);
cookie.config.compatibleVersion = fmtp[2]; // should be zero, uint8_t
cookie.config.bitDepth = fmtp[3]; // uint8_t expected to be 16
cookie.config.pb = fmtp[4]; // uint8_t should be 40;
cookie.config.mb = fmtp[5]; // uint8_t should be 10;
cookie.config.kb = fmtp[6]; // uint8_t should be 14;
cookie.config.numChannels = fmtp[7]; // uint8_t expected to be 2
cookie.config.maxRun = Swap16NtoB(fmtp[8]); // uint16_t expected to be 255
cookie.config.maxFrameBytes = Swap32NtoB(fmtp[9]); // uint32_t should be 0;
cookie.config.avgBitRate = Swap32NtoB(fmtp[10]); // uint32_t should be 0;;
cookie.config.sampleRate = Swap32NtoB(fmtp[11]); // uint32_t expected to be 44100;
theDecoder = new ALACDecoder;
theDecoder->Init(&cookie, sizeof(magicCookie));
return 0;
}
extern "C" int apple_alac_decode_frame(unsigned char *sampleBuffer, uint32_t bufferLength,
unsigned char *dest, int *outsize) {
uint32_t numFrames = 0;
BitBuffer theInputBuffer;
BitBufferInit(&theInputBuffer, sampleBuffer, bufferLength);
theDecoder->Decode(&theInputBuffer, dest, Swap32BtoN(cookie.config.frameLength),
cookie.config.numChannels, &numFrames);
*outsize = numFrames;
return 0;
}
extern "C" int apple_alac_terminate() {
delete (theDecoder);
return 0;
}
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