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Commit 84d1d4b1 authored by Antti S. Lankila's avatar Antti S. Lankila
Browse files

Bias estimate of sound pressure level upwards 

This patch introduced asymmetry in the loudness estimate
for the dynamic loudness correction. The effect is to
bias the estimated loudness towards the strongest sounds
heard in the last few seconds. This should fix the following
defects:

- reduce pumping treble associated with slow drum beats
- reduce the bass boost for sounds preceded by silence.

Change-Id: I5832ba7c43933ff4b71521ea4818aa9f7e3b4b65
parent 2474814f

media/libeffects/cyanogen-dsp/EffectEqualizer.cpp

+10 −8
Original line number Diff line number Diff line
@@ -243,14 +243,16 @@ int32_t EffectEqualizer::process(audio_buffer_t *in, audio_buffer_t *out) 
    for (uint32_t i = 0; i < in->frameCount; i ++) {

        if (mNextUpdate == 0) {

            float signalPowerDb = logf(mPowerSquared / mNextUpdateInterval / float(int64_t(1) << 48) + 1e-10f) / logf(10.0f) * 10.0f;

            signalPowerDb += 96.0f + 10.0f;



            /* Limit automatic EQ to sub-dB adjustments to limit the noise

             * introduced by updates. */

            if (mLoudness < signalPowerDb - .5) {

                mLoudness += .5;

            } else if (mLoudness > signalPowerDb + .5) {

                mLoudness -= .5;

            signalPowerDb += 96.0f - 6.0f;



            /* Limit automatic EQ to small adjustments to limit the noise

             * introduced by updates of EQ bands. Additionally, we bias

	     * the loudness estimate strongly towards the highest seen

	     * values, to avoid pumping artifacts. */

            if (mLoudness < signalPowerDb - 1.0f) {

                mLoudness += 1.0f;

            } else if (mLoudness > signalPowerDb - 0.1f) {

                mLoudness -= 0.1f;

            } else {

                mLoudness = signalPowerDb;

            }