cog/Plugins/Musepack/MusepackDecoder.m

//
//  MusepackFile.m
//  zyVorbis
//
//  Created by Vincent Spader on 1/23/05.
//  Copyright 2005 Vincent Spader All rights reserved.
//

#import "MusepackDecoder.h"

#import "Logging.h"

@implementation MusepackDecoder

mpc_int32_t ReadProc(mpc_reader *p_reader, void *ptr, mpc_int32_t size) {
	MusepackDecoder *decoder = (__bridge MusepackDecoder *)p_reader->data;

	return (mpc_int32_t)[[decoder source] read:ptr amount:size];
}

mpc_bool_t SeekProc(mpc_reader *p_reader, mpc_int32_t offset) {
	MusepackDecoder *decoder = (__bridge MusepackDecoder *)p_reader->data;

	return [[decoder source] seek:offset whence:SEEK_SET];
}

mpc_int32_t TellProc(mpc_reader *p_reader) {
	MusepackDecoder *decoder = (__bridge MusepackDecoder *)p_reader->data;

	return (mpc_int32_t)[[decoder source] tell];
}

mpc_int32_t GetSizeProc(mpc_reader *p_reader) {
	MusepackDecoder *decoder = (__bridge MusepackDecoder *)p_reader->data;

	if([[decoder source] seekable]) {
		long currentPos = [[decoder source] tell];

		[[decoder source] seek:0 whence:SEEK_END];
		long size = [[decoder source] tell];

		[[decoder source] seek:currentPos whence:SEEK_SET];

		if(size > INT32_MAX)
			size = INT32_MAX;

		return (mpc_int32_t)size;
	} else {
		return 0;
	}
}

mpc_bool_t CanSeekProc(mpc_reader *p_reader) {
	MusepackDecoder *decoder = (__bridge MusepackDecoder *)p_reader->data;

	return [[decoder source] seekable];
}

- (BOOL)open:(id<CogSource>)s {
	[self setSource:s];

	reader.read = ReadProc;
	reader.seek = SeekProc;
	reader.tell = TellProc;
	reader.get_size = GetSizeProc;
	reader.canseek = CanSeekProc;
	reader.data = (__bridge void *)(self);

	/* instantiate a demuxer with our reader */
	demux = mpc_demux_init(&reader);
	if(!demux) {
		DLog(@"Error initializing decoder.");
		return NO;
	}
	mpc_demux_get_info(demux, &info);

	bitrate = (int)(info.average_bitrate / 1000.0);
	frequency = info.sample_freq;

	totalFrames = mpc_streaminfo_get_length_samples(&info);

	[self willChangeValueForKey:@"properties"];
	[self didChangeValueForKey:@"properties"];

	return YES;
}

- (BOOL)writeToBuffer:(float *)sample_buffer fromBuffer:(const MPC_SAMPLE_FORMAT *)p_buffer frames:(unsigned)frames {
	unsigned n;

	unsigned p_size = frames * 2; // 2 = stereo
#ifdef MPC_FIXED_POINT
	const float float_scale = 1.0 / MPC_FIXED_POINT_SCALE;
#endif

	for(n = 0; n < p_size; n++) {
		float val;
#ifdef MPC_FIXED_POINT
		val = p_buffer[n] * float_scale;
#else
		val = p_buffer[n];
#endif

		//		sample_buffer[n] = CFSwapInt16LittleToHost(val);
		sample_buffer[n] = val;
	}

	//	m_data_bytes_written += p_size * (m_bps >> 3);
	return YES;
}

- (AudioChunk *)readAudio {
	int frames = 1024;
	void *buf = (void *)floatBuffer;

	int framesRead = 0;
	int bytesPerFrame = sizeof(float) * 2; // bitsPerSample == 32, channels == 2
	while(framesRead < frames) {
		// Fill from buffer, going by bufferFrames
		// if still needs more, decode and repeat
		if(bufferFrames == 0) {
			/* returns the length of the samples*/
			mpc_frame_info frame;
			frame.buffer = sampleBuffer;
			mpc_status err = mpc_demux_decode(demux, &frame);
			if(frame.bits == -1) {
				// decode error
				if(err != MPC_STATUS_OK)
					DLog(@"Decode error");
				return 0;
			} else // status>0 /* status == MPC_FRAME_LENGTH */
			{
			}

			bufferFrames = frame.samples;
		}

		int framesToRead = bufferFrames;
		if(bufferFrames > frames) {
			framesToRead = frames;
		}

		[self writeToBuffer:((float *)(buf + (framesRead * bytesPerFrame))) fromBuffer:sampleBuffer frames:framesToRead];

		frames -= framesToRead;
		framesRead += framesToRead;
		bufferFrames -= framesToRead;

		if(bufferFrames > 0) {
			memmove((uint8_t *)sampleBuffer, ((uint8_t *)sampleBuffer) + (framesToRead * bytesPerFrame), bufferFrames * bytesPerFrame);
		}
	}

	id audioChunkClass = NSClassFromString(@"AudioChunk");
	AudioChunk *chunk = [[audioChunkClass alloc] initWithProperties:[self properties]];
	[chunk assignSamples:floatBuffer frameCount:framesRead];

	return chunk;
}

- (void)close {
	if(demux) {
		mpc_demux_exit(demux);
		demux = NULL;
	}
}

- (void)dealloc {
	[self close];
}

- (long)seek:(long)sample {
	mpc_demux_seek_sample(demux, sample);

	return sample;
}

- (void)setSource:(id<CogSource>)s {
	source = s;
}

- (id<CogSource>)source {
	return source;
}

- (NSDictionary *)properties {
	return @{ @"bitrate": @(bitrate),
		      @"sampleRate": @(frequency),
		      @"totalFrames": @(totalFrames),
		      @"bitsPerSample": @(32),
		      @"floatingPoint": @(YES),
		      @"channels": @(2),
		      @"seekable": @([source seekable]),
		      @"codec": @"Musepack",
		      @"endian": @"host",
		      @"encoding": @"lossy" };
}

- (NSDictionary *)metadata {
	return @{};
}

+ (NSArray *)fileTypes {
	return @[@"mpc"];
}

+ (NSArray *)mimeTypes {
	return @[@"audio/x-musepack"];
}

+ (float)priority {
	return 1.0;
}

+ (NSArray *)fileTypeAssociations {
	return @[
		@[@"Musepack Audio File", @"mpc.icns", @"mpc"]
	];
}

@end