cog/Audio/Chain/AudioChunk.m

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//
// AudioChunk.m
// CogAudio Framework
//
// Created by Christopher Snowhill on 2/5/22.
//
#import "AudioChunk.h"
@implementation AudioChunk
- (id)init {
self = [super init];
if(self) {
chunkData = [[NSMutableData alloc] init];
formatAssigned = NO;
lossless = NO;
}
return self;
}
static const uint32_t AudioChannelConfigTable[] = {
0,
AudioConfigMono,
AudioConfigStereo,
AudioConfig3Point0,
AudioConfig4Point0,
AudioConfig5Point0,
AudioConfig5Point1,
AudioConfig6Point1,
AudioConfig7Point1,
0,
AudioConfig7Point1 | AudioChannelFrontCenterLeft | AudioChannelFrontCenterRight
};
+ (uint32_t)guessChannelConfig:(uint32_t)channelCount {
if(channelCount == 0) return 0;
if(channelCount > 32) return 0;
int ret = 0;
if(channelCount < (sizeof(AudioChannelConfigTable) / sizeof(AudioChannelConfigTable[0])))
ret = AudioChannelConfigTable[channelCount];
if(!ret) {
ret = (1 << channelCount) - 1;
}
assert([AudioChunk countChannels:ret] == channelCount);
return ret;
}
+ (uint32_t)channelIndexFromConfig:(uint32_t)channelConfig forFlag:(uint32_t)flag {
uint32_t index = 0;
for(uint32_t walk = 0; walk < 32; ++walk) {
uint32_t query = 1 << walk;
if(flag & query) return index;
if(channelConfig & query) ++index;
}
return ~0;
}
+ (uint32_t)extractChannelFlag:(uint32_t)index fromConfig:(uint32_t)channelConfig {
uint32_t toskip = index;
uint32_t flag = 1;
while(flag) {
if(channelConfig & flag) {
if(toskip == 0) break;
toskip--;
}
flag <<= 1;
}
return flag;
}
+ (uint32_t)countChannels:(uint32_t)channelConfig {
return __builtin_popcount(channelConfig);
}
+ (uint32_t)findChannelIndex:(uint32_t)flag {
uint32_t rv = 0;
if((flag & 0xFFFF) == 0) {
rv += 16;
flag >>= 16;
}
if((flag & 0xFF) == 0) {
rv += 8;
flag >>= 8;
}
if((flag & 0xF) == 0) {
rv += 4;
flag >>= 4;
}
if((flag & 0x3) == 0) {
rv += 2;
flag >>= 2;
}
if((flag & 0x1) == 0) {
rv += 1;
flag >>= 1;
}
assert(flag & 1);
return rv;
}
@synthesize lossless;
- (AudioStreamBasicDescription)format {
return format;
}
- (void)setFormat:(AudioStreamBasicDescription)informat {
formatAssigned = YES;
format = informat;
channelConfig = [AudioChunk guessChannelConfig:format.mChannelsPerFrame];
}
- (uint32_t)channelConfig {
return channelConfig;
}
- (void)setChannelConfig:(uint32_t)config {
if(formatAssigned) {
if(config == 0) {
config = [AudioChunk guessChannelConfig:format.mChannelsPerFrame];
}
}
channelConfig = config;
}
- (void)assignSamples:(const void *)data frameCount:(size_t)count {
if(formatAssigned) {
const size_t bytesPerPacket = format.mBytesPerPacket;
[chunkData appendBytes:data length:bytesPerPacket * count];
}
}
- (NSData *)removeSamples:(size_t)frameCount {
if(formatAssigned) {
const size_t bytesPerPacket = format.mBytesPerPacket;
const size_t byteCount = bytesPerPacket * frameCount;
NSData *ret = [chunkData subdataWithRange:NSMakeRange(0, byteCount)];
[chunkData replaceBytesInRange:NSMakeRange(0, byteCount) withBytes:NULL length:0];
return ret;
}
return [NSData data];
}
- (BOOL)isEmpty {
return [chunkData length] == 0;
}
- (size_t)frameCount {
if(formatAssigned) {
const size_t bytesPerPacket = format.mBytesPerPacket;
return [chunkData length] / bytesPerPacket;
}
return 0;
}
- (double)duration {
if(formatAssigned) {
const size_t bytesPerPacket = format.mBytesPerPacket;
const double sampleRate = format.mSampleRate;
return (double)([chunkData length] / bytesPerPacket) / sampleRate;
}
return 0.0;
}
@end