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Small refactoring change in delay_estimator.

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This CL produce the bit exact output and is a preparing step for an upcoming robust validation scheme.

TESTED=trybots, module_unittest
BUG=None
R=aluebs@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/4549004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5184 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
bjornv@webrtc.org 2013-11-28 07:59:04 +00:00
parent 19a40ff05b
commit eea079a376
1 changed files with 18 additions and 8 deletions
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26
webrtc/modules/audio_processing/utility/delay_estimator.c
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@ -202,9 +202,11 @@ int WebRtc_ProcessBinarySpectrum(BinaryDelayEstimator* self,
uint32_t binary_near_spectrum) {
int i = 0;
int candidate_delay = -1;
int valid_candidate = 0;
int32_t value_best_candidate = 32 << 9; // 32 in Q9, (max |mean_bit_counts|).
int32_t value_worst_candidate = 0;
int32_t valley_depth = 0;
assert(self != NULL);
if (self->near_history_size > 1) {
@ -249,6 +251,7 @@ int WebRtc_ProcessBinarySpectrum(BinaryDelayEstimator* self,
value_worst_candidate = self->mean_bit_counts[i];
}
}
valley_depth = value_worst_candidate - value_best_candidate;
// The |value_best_candidate| is a good indicator on the probability of
// |candidate_delay| being an accurate delay (a small |value_best_candidate|
@ -265,7 +268,7 @@ int WebRtc_ProcessBinarySpectrum(BinaryDelayEstimator* self,
// Update |minimum_probability|.
if ((self->minimum_probability > kProbabilityLowerLimit) &&
(value_worst_candidate - value_best_candidate > kProbabilityMinSpread)) {
(valley_depth > kProbabilityMinSpread)) {
// The "hard" threshold can't be lower than 17 (in Q9).
// The valley in the curve also has to be distinct, i.e., the
// difference between |value_worst_candidate| and |value_best_candidate| has
@ -281,14 +284,21 @@ int WebRtc_ProcessBinarySpectrum(BinaryDelayEstimator* self,
// Update |last_delay_probability|.
// We use a Markov type model, i.e., a slowly increasing level over time.
self->last_delay_probability++;
if (value_worst_candidate > value_best_candidate + kProbabilityOffset) {
// Reliable delay value for usage.
if (value_best_candidate < self->minimum_probability) {
self->last_delay = candidate_delay;
}
// Validate |candidate_delay|. We have a reliable instantaneous delay
// estimate if
// 1) The valley is distinct enough (|valley_depth| > |kProbabilityOffset|)
// and
// 2) The depth of the valley is deep enough
// (|value_best_candidate| < |minimum_probability|)
// and deeper than the best estimate so far
// (|value_best_candidate| < |last_delay_probability|)
valid_candidate = ((valley_depth > kProbabilityOffset) &&
((value_best_candidate < self->minimum_probability) ||
(value_best_candidate < self->last_delay_probability)));
if (valid_candidate) {
self->last_delay = candidate_delay;
if (value_best_candidate < self->last_delay_probability) {
self->last_delay = candidate_delay;
// Reset |last_delay_probability|.
self->last_delay_probability = value_best_candidate;
}
}