kode54
/
cog
2
1
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[Audio Threads] Remove unused code 

This code turned out to be somewhat of a mistake to employ, so it's now
being removed, and shall not be re-added, as it doesn't really work.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>
swiftingly
Christopher Snowhill 2022-06-18 23:02:24 -07:00
parent 84d0cbee3c
commit 1c36869e57
1 changed files with 0 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
Audio/Chain/Node.m
View File

@ -17,101 +17,6 @@
#import <mach/mach_time.h>
// This workgroup attribute needs to be initialized.
static os_workgroup_attr_s attr = OS_WORKGROUP_ATTR_INITIALIZER_DEFAULT;
// One nanosecond in seconds.
static const double kOneNanosecond = 1.0e9;
// The I/O interval time in seconds.
static const double kIOIntervalTime = 0.020;
// The clock identifier that specifies interval timestamps.
static const os_clockid_t clockId = OS_CLOCK_MACH_ABSOLUTE_TIME;
// Enables time-contraint policy and priority suitable for low-latency,
// glitch-resistant audio.
BOOL SetPriorityRealtimeAudio(mach_port_t mach_thread_id) {
kern_return_t result;
// Increase thread priority to real-time.
// Please note that the thread_policy_set() calls may fail in
// rare cases if the kernel decides the system is under heavy load
// and is unable to handle boosting the thread priority.
// In these cases we just return early and go on with life.
// Make thread fixed priority.
thread_extended_policy_data_t policy;
policy.timeshare = 0; // Set to 1 for a non-fixed thread.
result = thread_policy_set(mach_thread_id,
THREAD_EXTENDED_POLICY,
(thread_policy_t)&policy,
THREAD_EXTENDED_POLICY_COUNT);
if(result != KERN_SUCCESS) {
DLog(@"thread_policy_set extended policy failure: %d", result);
return NO;
}
// Set to relatively high priority.
thread_precedence_policy_data_t precedence;
precedence.importance = 63;
result = thread_policy_set(mach_thread_id,
THREAD_PRECEDENCE_POLICY,
(thread_policy_t)&precedence,
THREAD_PRECEDENCE_POLICY_COUNT);
if(result != KERN_SUCCESS) {
DLog(@"thread_policy_set precedence policy failure: %d", result);
return NO;
}
// Most important, set real-time constraints.
// Define the guaranteed and max fraction of time for the audio thread.
// These "duty cycle" values can range from 0 to 1. A value of 0.5
// means the scheduler would give half the time to the thread.
// These values have empirically been found to yield good behavior.
// Good means that audio performance is high and other threads won't starve.
const double kGuaranteedAudioDutyCycle = 0.75;
const double kMaxAudioDutyCycle = 0.85;
// Define constants determining how much time the audio thread can
// use in a given time quantum. All times are in milliseconds.
// About 128 frames @44.1KHz
const double kTimeQuantum = 2.9;
// Time guaranteed each quantum.
const double kAudioTimeNeeded = kGuaranteedAudioDutyCycle * kTimeQuantum;
// Maximum time each quantum.
const double kMaxTimeAllowed = kMaxAudioDutyCycle * kTimeQuantum;
// Get the conversion factor from milliseconds to absolute time
// which is what the time-constraints call needs.
mach_timebase_info_data_t tb_info;
mach_timebase_info(&tb_info);
double ms_to_abs_time =
((double)tb_info.denom / (double)tb_info.numer) * 1000000;
thread_time_constraint_policy_data_t time_constraints;
time_constraints.period = kTimeQuantum * ms_to_abs_time;
time_constraints.computation = kAudioTimeNeeded * ms_to_abs_time;
time_constraints.constraint = kMaxTimeAllowed * ms_to_abs_time;
time_constraints.preemptible = 0;
result = thread_policy_set(mach_thread_id,
THREAD_TIME_CONSTRAINT_POLICY,
(thread_policy_t)&time_constraints,
THREAD_TIME_CONSTRAINT_POLICY_COUNT);
if(result != KERN_SUCCESS) {
DLog(@"thread_policy_set constraint policy failure: %d", result);
return NO;
}
return YES;
}
@implementation Node
- (id)initWithController:(id)c previous:(id)p {