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[api] roc-streaminggh-688: Refine dynamic latency configuration
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Latency parameters:
 - target_latency (0 = adaptive, >0 = fixed)
 - latency_tolerance
 for adaptive mode only:
 - start_target_latency
 - min_target_latency
 - max_target_latency

On receiver, you always need to set latency parameters,
if profile is INTACT or not. Receiver always checks
latency tolerance violations and always needs starting
value for the latency.

On sender, if profile is INTACT, all latency parameters
should be zero. Otherwise, all latency parameters should
match same parameters on receiver.

Other changes:
 - fixes in adapters
 - deduce_defaults updated to new rules
 - latency tuner updated to new rules
 - add panics to latency tuner
 - comments are updated
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@gavv
gavv committed Jul 31, 2024
1 parent b57c037 commit 14eff87
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Showing 9 changed files with 326 additions and 349 deletions.
179 changes: 86 additions & 93 deletions src/internal_modules/roc_audio/latency_config.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,14 +17,13 @@ namespace {

LatencyTunerProfile deduce_tuner_profile(const LatencyTunerBackend tuner_backend,
const core::nanoseconds_t target_latency,
const core::nanoseconds_t start_latency,
const core::nanoseconds_t start_target_latency,
const bool is_adaptive,
const bool is_receiver) {
if (is_receiver) {
if (tuner_backend == LatencyTunerBackend_Niq) {
// Use start_latency in adaptive mode or target_latency in fixed mode.
const core::nanoseconds_t configured_latency =
is_adaptive ? start_latency : target_latency;
is_adaptive ? start_target_latency : target_latency;

// If latency is low, we assume network jitter is also low. In this
// case we use responsive profile. Gradual profile could cause
Expand All @@ -48,38 +47,39 @@ LatencyTunerProfile deduce_tuner_profile(const LatencyTunerBackend tuner_backend
}
}

core::nanoseconds_t deduce_start_latency(const core::nanoseconds_t min_latency,
const core::nanoseconds_t max_latency,
const core::nanoseconds_t default_latency) {
if (min_latency != 0 || max_latency != 0) {
core::nanoseconds_t
deduce_start_target_latency(const core::nanoseconds_t min_target_latency,
const core::nanoseconds_t max_target_latency,
const core::nanoseconds_t default_latency) {
if (min_target_latency != 0 || max_target_latency != 0) {
// If min and max latency are provided explicitly, start in the middle.
return min_latency + (max_latency - min_latency) / 2;
return min_target_latency + (max_target_latency - min_target_latency) / 2;
} else {
// Otherwise start from default value.
return default_latency;
}
}

void deduce_min_max_latency(const core::nanoseconds_t start_latency,
core::nanoseconds_t& min_latency,
core::nanoseconds_t& max_latency) {
void deduce_min_max_target_latency(const core::nanoseconds_t start_target_latency,
core::nanoseconds_t& min_target_latency,
core::nanoseconds_t& max_target_latency) {
// By default, allow wide range for latency tuning.
min_latency = 0;
max_latency = start_latency * 5;
min_target_latency = std::min(core::Millisecond * 15, start_target_latency / 5);
max_target_latency = start_target_latency * 5;
}

core::nanoseconds_t deduce_latency_tolerance(const core::nanoseconds_t target_latency,
const core::nanoseconds_t start_latency,
const bool is_adaptive,
const bool is_receiver) {
core::nanoseconds_t
deduce_latency_tolerance(const core::nanoseconds_t target_latency,
const core::nanoseconds_t start_target_latency,
const bool is_adaptive,
const bool is_receiver) {
// On sender, apply multiplier to make default tolerance a bit higher than
// on receiver. This way, if bounding is enabled on both sides, receiver
// will always trigger first.
const int multiplier = is_receiver ? 1 : 4;

// Use start_latency in adaptive mode or target_latency in fixed mode.
const core::nanoseconds_t configured_latency =
is_adaptive ? start_latency : target_latency;
is_adaptive ? start_target_latency : target_latency;

// Out formula doesn't work well on latencies close to zero.
const core::nanoseconds_t floored_latency =
Expand All @@ -104,7 +104,7 @@ core::nanoseconds_t deduce_stale_tolerance(const core::nanoseconds_t latency_tol
return std::max(latency_tolerance / 4, 10 * core::Millisecond);
}

size_t deduce_sliding_window(const LatencyTunerProfile tuner_profile) {
size_t deduce_sliding_window_len(const LatencyTunerProfile tuner_profile) {
if (tuner_profile == audio::LatencyTunerProfile_Responsive) {
// Responsive profile requires faster reactions to changes
// of link characteristics.
Expand All @@ -116,35 +116,39 @@ size_t deduce_sliding_window(const LatencyTunerProfile tuner_profile) {

bool validate_adaptive_latency(const core::nanoseconds_t target_latency,
const core::nanoseconds_t latency_tolerance,
const core::nanoseconds_t start_latency,
const core::nanoseconds_t min_latency,
const core::nanoseconds_t max_latency) {
const core::nanoseconds_t start_target_latency,
const core::nanoseconds_t min_target_latency,
const core::nanoseconds_t max_target_latency) {
roc_panic_if(target_latency != 0);

if (latency_tolerance < 0) {
roc_log(LogError, "latency config: latency_tolerance must be >= 0");
return false;
}

if (start_latency < 0) {
roc_log(LogError, "latency config: start_latency must be >= 0");
if (start_target_latency < 0) {
roc_log(LogError, "latency config: start_target_latency must be >= 0");
return false;
}

if (min_latency != 0 || max_latency != 0) {
if (min_latency < 0 || max_latency < 0) {
roc_log(LogError, "latency config: min_latency and max_latency must be >= 0");
if (min_target_latency != 0 || max_target_latency != 0) {
if (min_target_latency < 0 || max_target_latency < 0) {
roc_log(
LogError,
"latency config: min_target_latency and max_target_latency must be >= 0");
return false;
}
if (min_latency > max_latency) {
roc_log(LogError, "latency config: min_latency must be <= max_latency");
if (min_target_latency > max_target_latency) {
roc_log(LogError,
"latency config: min_target_latency must be <= max_target_latency");
return false;
}
if (start_latency != 0
&& (start_latency < min_latency || start_latency > max_latency)) {
roc_log(
LogError,
"latency config: start_latency must be in [min_latency; max_latency]");
if (start_target_latency != 0
&& (start_target_latency < min_target_latency
|| start_target_latency > max_target_latency)) {
roc_log(LogError,
"latency config: start_target_latency must be in range"
" [min_target_latency; max_target_latency]");
return false;
}
}
Expand All @@ -154,9 +158,9 @@ bool validate_adaptive_latency(const core::nanoseconds_t target_latency,

bool validate_fixed_latency(const core::nanoseconds_t target_latency,
const core::nanoseconds_t latency_tolerance,
const core::nanoseconds_t start_latency,
const core::nanoseconds_t min_latency,
const core::nanoseconds_t max_latency) {
const core::nanoseconds_t start_target_latency,
const core::nanoseconds_t min_target_latency,
const core::nanoseconds_t max_target_latency) {
roc_panic_if(target_latency == 0);

if (target_latency < 0) {
Expand All @@ -169,38 +173,30 @@ bool validate_fixed_latency(const core::nanoseconds_t target_latency,
return false;
}

if (start_latency != 0 || min_latency != 0 || max_latency != 0) {
roc_log(LogError,
"latency config: start_latency, min_latency, max_latency"
" may be used only when adaptive latency is enabled"
" (i.e. target_latency == 0)");
if (start_target_latency != 0 || min_target_latency != 0 || max_target_latency != 0) {
roc_log(
LogError,
"latency config: start_target_latency, min_target_latency, max_target_latency"
" may be used only when adaptive latency is enabled"
" (i.e. target_latency == 0)");
return false;
}

return true;
}

bool validate_intact_latency(const core::nanoseconds_t target_latency,
const core::nanoseconds_t latency_tolerance,
const core::nanoseconds_t start_latency,
const core::nanoseconds_t min_latency,
const core::nanoseconds_t max_latency) {
if (target_latency < 0) {
roc_log(LogError, "latency config: target_latency must be >= 0");
return false;
}

if (latency_tolerance < 0) {
roc_log(LogError, "latency config: latency_tolerance must be >= 0");
return false;
}

if (start_latency != 0 || min_latency != 0 || max_latency != 0) {
bool validate_no_latency(const core::nanoseconds_t target_latency,
const core::nanoseconds_t latency_tolerance,
const core::nanoseconds_t start_target_latency,
const core::nanoseconds_t min_target_latency,
const core::nanoseconds_t max_target_latency) {
if (target_latency != 0 || latency_tolerance != 0 || start_target_latency != 0
|| min_target_latency != 0 || max_target_latency != 0) {
roc_log(LogError,
"latency config:"
" start_latency, min_latency, max_latency"
" may be used only when latency tuning is enabled"
" (i.e. latency profile is not \"intact\")");
" on sender, target_latency, latency_tolerance,"
" start_target_latency, min_target_latency, max_target_latency"
" aren't used and must be zero if latency profile is \"intact\"");
return false;
}

Expand All @@ -211,71 +207,68 @@ bool validate_intact_latency(const core::nanoseconds_t target_latency,

bool LatencyConfig::deduce_defaults(core::nanoseconds_t default_latency,
bool is_receiver) {
// Adaptive latency mode.
// Whether we're using adaptive latency mode.
const bool is_adaptive = target_latency == 0;

if (tuner_backend == LatencyTunerBackend_Default) {
tuner_backend = LatencyTunerBackend_Niq;
}

if (tuner_profile == LatencyTunerProfile_Default) {
tuner_profile = deduce_tuner_profile(tuner_backend, target_latency, start_latency,
is_adaptive, is_receiver);
tuner_profile =
deduce_tuner_profile(tuner_backend, target_latency, start_target_latency,
is_adaptive, is_receiver);
}

if (tuner_profile != LatencyTunerProfile_Intact) {
// If latency tuning and bounds checking are enabled.
// On receiver, we always need to know latency parameters, no matter who is doing
// latency adjustment, receiver or sender.
// On sender, we need latency parameters only if sender is doing latency adjustment
// (latency profile is not "intact").
const bool want_latency_params =
is_receiver || tuner_profile != LatencyTunerProfile_Intact;

if (want_latency_params) {
if (is_adaptive) {
if (!validate_adaptive_latency(target_latency, latency_tolerance,
start_latency, min_latency, max_latency)) {
start_target_latency, min_target_latency,
max_target_latency)) {
return false;
}

if (start_latency == 0) {
start_latency =
deduce_start_latency(min_latency, max_latency, default_latency);
if (start_target_latency == 0) {
start_target_latency = deduce_start_target_latency(
min_target_latency, max_target_latency, default_latency);
}

if (min_latency == 0 && max_latency == 0) {
deduce_min_max_latency(start_latency, min_latency, max_latency);
if (min_target_latency == 0 && max_target_latency == 0) {
deduce_min_max_target_latency(start_target_latency, min_target_latency,
max_target_latency);
}
} else {
if (!validate_fixed_latency(target_latency, latency_tolerance, start_latency,
min_latency, max_latency)) {
if (!validate_fixed_latency(target_latency, latency_tolerance,
start_target_latency, min_target_latency,
max_target_latency)) {
return false;
}
}

if (latency_tolerance == 0) {
latency_tolerance = deduce_latency_tolerance(target_latency, start_latency,
is_adaptive, is_receiver);
latency_tolerance = deduce_latency_tolerance(
target_latency, start_target_latency, is_adaptive, is_receiver);
}

if (stale_tolerance == 0) {
stale_tolerance = deduce_stale_tolerance(latency_tolerance);
}
} else {
// If latency tuning is disabled.
if (!validate_intact_latency(target_latency, latency_tolerance, start_latency,
min_latency, max_latency)) {
if (!validate_no_latency(target_latency, latency_tolerance, start_target_latency,
min_target_latency, max_target_latency)) {
return false;
}

if (target_latency != 0) {
// If bounds checking is enabled.
if (latency_tolerance == 0) {
latency_tolerance = deduce_latency_tolerance(
target_latency, start_latency, is_adaptive, is_receiver);
}

if (stale_tolerance == 0) {
stale_tolerance = deduce_stale_tolerance(latency_tolerance);
}
}
}

if (sliding_window_length == 0) {
sliding_window_length = deduce_sliding_window(tuner_profile);
sliding_window_length = deduce_sliding_window_len(tuner_profile);
}

return true;
Expand Down
20 changes: 10 additions & 10 deletions src/internal_modules/roc_audio/latency_config.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,20 +37,20 @@ enum LatencyTunerBackend {
};

//! Latency tuner profile.
//! Defines whether and how we tune latency on fly to compensate clock
//! Defines whether and how we adjust latency on fly to compensate clock
//! drift and jitter.
enum LatencyTunerProfile {
//! Deduce best default for given settings.
LatencyTunerProfile_Default,

//! Do not tune latency.
//! Do not adjust latency.
LatencyTunerProfile_Intact,

//! Fast and responsive tuning.
//! Fast and responsive adjustment.
//! Good for lower network latency and jitter.
LatencyTunerProfile_Responsive,

//! Slow and smooth tuning.
//! Slow and smooth adjustment.
//! Good for higher network latency and jitter.
LatencyTunerProfile_Gradual
};
Expand Down Expand Up @@ -96,7 +96,7 @@ struct LatencyConfig {
//! @note
//! If zero, default value is used.
//! Negative value is an error.
core::nanoseconds_t start_latency;
core::nanoseconds_t start_target_latency;

//! Minimum latency for adaptive mode.
//! @remarks
Expand All @@ -105,7 +105,7 @@ struct LatencyConfig {
//! Can be used only in adaptive latency mode.
//! @note
//! If both min_latency and max_latency are zero, defaults are used.
core::nanoseconds_t min_latency;
core::nanoseconds_t min_target_latency;

//! Maximum latency for adaptive mode.
//! @remarks
Expand All @@ -114,7 +114,7 @@ struct LatencyConfig {
//! Can be used only in adaptive latency mode.
//! @note
//! If both min_latency and max_latency are zero, defaults are used.
core::nanoseconds_t max_latency;
core::nanoseconds_t max_target_latency;

//! Maximum delay since last packet before queue is considered stalling.
//! @remarks
Expand Down Expand Up @@ -176,9 +176,9 @@ struct LatencyConfig {
, tuner_profile(LatencyTunerProfile_Default)
, target_latency(0)
, latency_tolerance(0)
, start_latency(0)
, min_latency(0)
, max_latency(0)
, start_target_latency(0)
, min_target_latency(0)
, max_target_latency(0)
, stale_tolerance(0)
, scaling_interval(5 * core::Millisecond)
, scaling_tolerance(0.005f)
Expand Down
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