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calculate_rms: improved and polished

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Rewrite using the new templates to avoid custom code and increase
performance.
This commit is contained in:
Martin Pulec
2021-08-05 14:49:38 +02:00
parent 5065c79f81
commit 4f9a69d4f0
1 changed files with 42 additions and 36 deletions
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78
src/audio/utils.cpp
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@@ -88,21 +88,38 @@ template<> int32_t load_sample<4>(const char *data) {
return *reinterpret_cast<const int32_t *>(data);
}
static double get_normalized(const int8_t *in, int bps) {
int64_t sample = 0;
bool negative = false;
/**
* @brief Calculates mean and peak RMS from audio samples
*
* @param[in] frame audio frame
* @param[in] channel channel index to calculate RMS to
* @param[out] peak peak RMS
* @returns mean RMS
*/
template<int BPS>
static double calculate_rms_helper(const char *channel_data, int sample_count, double *peak)
{
double sum = 0;
*peak = 0;
for (int i = 0; i < sample_count; i += 1) {
double val = load_sample<BPS>(channel_data + i * BPS) / static_cast<double>(1U << (BPS * CHAR_BIT - 1U));
sum += val;
*peak = max(fabs(val), *peak);
}
for (int j = 0; j < bps; ++j) {
sample = (sample | ((((const uint8_t *)in)[j]) << (uint64_t)(8ull * j)));
double average = sum / sample_count;
double sumMeanSquare = 0.0;
for (int i = 0; i < sample_count; i += 1) {
sumMeanSquare += pow(load_sample<BPS>(channel_data + i * BPS) / static_cast<double>(1U << (BPS * CHAR_BIT - 1U))
- average, 2.0);
}
if ((int8_t)(in[bps - 1] < 0))
negative = true;
if (negative) {
for (int i = bps; i < 8; ++i) {
sample = (sample | (255ull << (8ull * i)));
}
}
return (double) sample / ((1 << (bps * 8 - 1)));
double averageMeanSquare = sumMeanSquare / sample_count;
double rootMeanSquare = sqrt(averageMeanSquare);
return rootMeanSquare;
}
/**
@@ -116,31 +133,20 @@ static double get_normalized(const int8_t *in, int bps) {
double calculate_rms(audio_frame2 *frame, int channel, double *peak)
{
assert(frame->get_codec() == AC_PCM);
double sum = 0;
*peak = 0;
int sample_count = frame->get_data_len(channel) / frame->get_bps();
const char *channel_data = frame->get_data(channel);
for (size_t i = 0; i < frame->get_data_len(channel); i += frame->get_bps()) {
double val = get_normalized((const int8_t *) channel_data + i, frame->get_bps());
sum += val;
if (fabs(val) > *peak) {
*peak = fabs(val);
}
switch (frame->get_bps()) {
case 1:
return calculate_rms_helper<1>(frame->get_data(channel), sample_count, peak);
case 2:
return calculate_rms_helper<2>(frame->get_data(channel), sample_count, peak);
case 3:
return calculate_rms_helper<3>(frame->get_data(channel), sample_count, peak);
case 4:
return calculate_rms_helper<4>(frame->get_data(channel), sample_count, peak);
default:
LOG(LOG_LEVEL_FATAL) << "Wrong BPS " << frame->get_bps() << "\n";
abort();
}
double average = sum / sample_count;
double sumMeanSquare = 0.0;
for (size_t i = 0; i < frame->get_data_len(channel); i += frame->get_bps()) {
sumMeanSquare += pow(get_normalized((const int8_t *) channel_data + i, frame->get_bps())
- average, 2.0);
}
double averageMeanSquare = sumMeanSquare / sample_count;
double rootMeanSquare = sqrt(averageMeanSquare);
return rootMeanSquare;
}
bool audio_desc_eq(struct audio_desc a1, struct audio_desc a2) {