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