c-goertzel

C version of the Optimized Goertzel algorithm (https://www.embedded.com/the-goertzel-algorithm/) with DTMF detector code.

Usage

DTMF detector

Please refer to the example used as a test on the test/test.c file. In short terms:

1. Init a goertzel_dtmf_state structure by calling goertzel_dtmf_detect with the sample rate and the number of samples to process.
2. Call goertzel_dtmf_add_sample_pcm8 or goertzel_dtmf_add_sample_pcm16 to add the configured number of samples.
3. Detect the DTMF symbol by reading the return value of goertzel_dtmf_detect. The thresholds should be tweaked accordingly to the amplitude and sampling frequency that's being used.

Tone detector (pure Goertzel)

1. Init a goertzel_state structure by calling goertzel_init with the sample rate and the number of samples to process.
2. Call goertzel_process_sample_pcm8 or goertzel_process_sample_pcm16 to add the configured number of samples.
3. Detect the squared Goertzel magnitude with the return value of goertzel_get_squared_magnitude. The thresholds should be tweaked accordingly to the amplitude and sampling frequency that's being used. If the magnitude value is required, goertzel_get_magnitude is available.