#include #include #include #define buffer_maxlength 12288 #define buffer_tlength_fragsize 12288 #define buffer_prebuf 32 #define DEFAULT_STEREO 1 #define DEFAULT_STEREO_POLAR 0 #define DEFAULT_CLIPPER_THRESHOLD 1.0f #define DEFAULT_SCA_FREQUENCY 67000.0f #define DEFAULT_SCA_DEVIATION 7000.0f #define DEFAULT_SCA_CLIPPER_THRESHOLD 1.0f // Full deviation, if you set this to 0.5 then you may as well set the deviation to 3.5k #define DEFAULT_PREEMPHASIS_TAU 50e-6 // Europe, the freedomers use 75µs //#define USB #include "../lib/constants.h" #include "../lib/oscillator.h" #include "../lib/filters.h" #include "../lib/fm_modulator.h" #define INPUT_SAMPLE_RATE 32000 // make sure that the output is a multiple of this #define SAMPLE_RATE 192000 #define INPUT_DEVICE "FM_Audio.monitor" #define OUTPUT_DEVICE "alsa_output.platform-soc_sound.stereo-fallback" #define MPX_DEVICE "FM_MPX.monitor" // #define SCA_DEVICE "" #define BUFFER_SIZE 2048 #include #include #define MASTER_VOLUME 1.0f // Volume of everything combined, for calibration #define AUDIO_VOLUME 1.0f // Audio volume, before clipper #define MONO_VOLUME 0.45f // L+R Signal #define PILOT_VOLUME 0.09f // 19 KHz Pilot #define STEREO_VOLUME 0.45f // L-R signal, should be same as MONO #define SCA_VOLUME 0.1f // FM SCA signal, 10% #define MPX_VOLUME 1.0f // Passtrough #define MPX_CLIPPER_THRESHOLD 1.0f #define LPF_CUTOFF 15000 // Should't need to be changed volatile sig_atomic_t to_run = 1; void uninterleave(const float *input, float *left, float *right, size_t num_samples) { // For stereo, usually it is like this: LEFT RIGHT LEFT RIGHT LEFT RIGHT so this is used to get LEFT LEFT LEFT and RIGHT RIGHT RIGHT for (size_t i = 0; i < num_samples/2; i++) { left[i] = input[i * 2]; right[i] = input[i * 2 + 1]; } } static void stop(int signum) { (void)signum; printf("\nReceived stop signal.\n"); to_run = 0; } void show_version() { printf("fm95 (an FM Processor by radio95) version 1.3\n"); } void show_help(char *name) { printf( "Usage: %s\n" " -m,--mono Force Mono [default: %d]\n" " -s,--stereo Force Stereo [default: %d]\n" " -i,--input Override input device [default: %s]\n" " -o,--output Override output device [default: %s]\n" " -M,--mpx Override MPX input device [default: %s]\n" " -C,--sca Override the SCA input device [default: %s]\n" " -f,--sca_freq Override the SCA frequency [default: %.1f]\n" " -F,--sca_dev Override the SCA deviation [default: %.2f]\n" " -L,--sca_clip Override the SCA clipper threshold [default: %.2f]\n" " -c,--clipper Override the clipper threshold [default: %.2f]\n" " -P,--polar Force Polar Stereo (does not take effect with -m%s)\n" " -g,--ge Force Zenith/GE stereo (does not take effect with -m%s)\n" " -R,--preemp Override preemphasis [default: %.2f µs]\n" " -V,--calibrate Enable Calibration mode [default: off]\n" " -A,--master_vol Set master volume [default: %.3f]\n" " -v,--audio_vol Set audio volume [default: %.3f]\n" ,name ,DEFAULT_STEREO^1 ,DEFAULT_STEREO ,INPUT_DEVICE ,OUTPUT_DEVICE #ifdef MPX_DEVICE ,MPX_DEVICE #else ,"not set" #endif #ifdef SCA_DEVICE ,SCA_DEVICE #else ,"not set" #endif ,DEFAULT_SCA_FREQUENCY ,DEFAULT_SCA_DEVIATION ,DEFAULT_SCA_CLIPPER_THRESHOLD ,DEFAULT_CLIPPER_THRESHOLD ,(DEFAULT_STEREO_POLAR == 1) ? ", default" : "" ,(DEFAULT_STEREO_POLAR == 1) ? "" : ", default" ,DEFAULT_PREEMPHASIS_TAU/0.000001 ,MASTER_VOLUME ,AUDIO_VOLUME ); } int main(int argc, char **argv) { show_version(); pa_simple *mpx_device; pa_simple *sca_device; pa_simple *output_device; float clipper_threshold = DEFAULT_CLIPPER_THRESHOLD; int stereo = DEFAULT_STEREO; int polar_stereo = DEFAULT_STEREO_POLAR; float sca_frequency = DEFAULT_SCA_FREQUENCY; float sca_deviation = DEFAULT_SCA_DEVIATION; float sca_clipper_threshold = DEFAULT_SCA_CLIPPER_THRESHOLD; char audio_input_device[64] = INPUT_DEVICE; char audio_output_device[64] = OUTPUT_DEVICE; #ifndef MPX_DEVICE char audio_mpx_device[64] = "\0"; #else char audio_mpx_device[64] = MPX_DEVICE; #endif #ifndef SCA_DEVICE char audio_sca_device[64] = "\0"; #else char audio_sca_device[64] = SCA_DEVICE; #endif float preemphasis_tau = DEFAULT_PREEMPHASIS_TAU; int calibration_mode = 0; float master_volume = MASTER_VOLUME; float audio_volume = AUDIO_VOLUME; // #region Parse Arguments int opt; const char *short_opt = "msi:o:apM:C:f:F:L:c:l:PgSDR:VA:v:h"; struct option long_opt[] = { {"mono", no_argument, NULL, 'm'}, {"stereo", no_argument, NULL, 's'}, {"input", required_argument, NULL, 'i'}, {"output", required_argument, NULL, 'o'}, {"mpx", required_argument, NULL, 'M'}, {"sca", required_argument, NULL, 'C'}, {"sca_freq", required_argument, NULL, 'f'}, {"sca_dev", required_argument, NULL, 'F'}, {"sca_clip", required_argument, NULL, 'L'}, {"clipper", required_argument, NULL, 'c'}, {"polar", no_argument, NULL, 'P'}, {"ge", no_argument, NULL, 'g'}, {"preemp", required_argument, NULL, 'R'}, {"calibrate", no_argument, NULL, 'V'}, {"master_vol", required_argument, NULL, 'A'}, {"audio_vol", required_argument, NULL, 'v'}, {"help", no_argument, NULL, 'h'}, {0, 0, 0, 0} }; while((opt = getopt_long(argc, argv, short_opt, long_opt, NULL)) != -1) { switch(opt) { case 'm': // Mono stereo = 0; break; case 's': // Stereo stereo = 1; break; case 'i': // Input Device memcpy(audio_input_device, optarg, 63); break; case 'o': // Output Device memcpy(audio_output_device, optarg, 63); break;; case 'M': //MPX in memcpy(audio_mpx_device, optarg, 63); break; case 'C': //SCA in memcpy(audio_sca_device, optarg, 63); break; case 'f': //SCA freq sca_frequency = strtof(optarg, NULL); break; case 'F': //SCA deviation sca_deviation = strtof(optarg, NULL); break; case 'L': //SCA clip sca_clipper_threshold = strtof(optarg, NULL); break; case 'c': //Clipper clipper_threshold = strtof(optarg, NULL); break; case 'P': //Polar polar_stereo = 1; break; case 'g': //GE polar_stereo = 0; break; case 'R': // Preemp preemphasis_tau = strtof(optarg, NULL)*0.000001; break; case 'V': // Calibration calibration_mode = 1; break; case 'A': // Master vol master_volume = strtof(optarg, NULL); break; case 'v': // Audio Volume audio_volume = strtof(optarg, NULL); break; case 'h': show_help(argv[0]); return 1; } } // #endregion // #region Setup devices // Define formats and buffer atributes pa_sample_spec stereo_format = { .format = PA_SAMPLE_FLOAT32NE, //Float32 NE, or Float32 Native Endian, the float in c uses the endianess of your pc, or native endian, and float is float32, and double is float64 .channels = 2, .rate = SAMPLE_RATE // Same sample rate makes it easy, leave the resampling to pipewire, it should know better }; pa_sample_spec mono_format = { .format = PA_SAMPLE_FLOAT32NE, .channels = 1, .rate = SAMPLE_RATE }; pa_sample_spec main_input_format = { .format = PA_SAMPLE_FLOAT32NE, .channels = 2, .rate = INPUT_SAMPLE_RATE }; pa_buffer_attr input_buffer_atr = { .maxlength = buffer_maxlength, .fragsize = buffer_tlength_fragsize }; pa_buffer_attr output_buffer_atr = { .maxlength = buffer_maxlength, .tlength = buffer_tlength_fragsize, .prebuf = buffer_prebuf }; int opentime_pulse_error; printf("Connecting to input device... (%s)\n", audio_input_device); pa_simple *input_device = pa_simple_new( NULL, "fm95", PA_STREAM_RECORD, audio_input_device, "Main Audio Input", &main_input_format, NULL, &input_buffer_atr, &opentime_pulse_error ); if (!input_device) { fprintf(stderr, "Error: cannot open input device: %s\n", pa_strerror(opentime_pulse_error)); return 1; } if(strlen(audio_mpx_device) != 0) { printf("Connecting to MPX device... (%s)\n", audio_mpx_device); mpx_device = pa_simple_new( NULL, "fm95", PA_STREAM_RECORD, audio_mpx_device, "MPX Input", &mono_format, NULL, &input_buffer_atr, &opentime_pulse_error ); if (!mpx_device) { fprintf(stderr, "Error: cannot open MPX device: %s\n", pa_strerror(opentime_pulse_error)); pa_simple_free(input_device); return 1; } } if(strlen(audio_sca_device) != 0) { printf("Connecting to SCA device... (%s)\n", audio_sca_device); sca_device = pa_simple_new( NULL, "fm95", PA_STREAM_RECORD, audio_sca_device, "SCA Input", &mono_format, NULL, &input_buffer_atr, &opentime_pulse_error ); if (!sca_device) { fprintf(stderr, "Error: cannot open SCA device: %s\n", pa_strerror(opentime_pulse_error)); pa_simple_free(input_device); if(strlen(audio_mpx_device) != 0) pa_simple_free(mpx_device); return 1; } } printf("Connecting to output device... (%s)\n", audio_output_device); output_device = pa_simple_new( NULL, "StereoEncoder", PA_STREAM_PLAYBACK, audio_output_device, "MPX Output", &mono_format, NULL, &output_buffer_atr, &opentime_pulse_error ); if (!output_device) { fprintf(stderr, "Error: cannot open output device: %s\n", pa_strerror(opentime_pulse_error)); pa_simple_free(input_device); if(strlen(audio_mpx_device) != 0) pa_simple_free(mpx_device); if(strlen(audio_sca_device) != 0) pa_simple_free(sca_device); return 1; } // #endregion if(calibration_mode) { Oscillator osc; init_oscillator(&osc, 400, SAMPLE_RATE); signal(SIGINT, stop); signal(SIGTERM, stop); int pulse_error; float output[BUFFER_SIZE]; // MPX, this goes to the output while(to_run) { for (int i = 0; i < BUFFER_SIZE; i++) { output[i] = get_oscillator_sin_sample(&osc)*master_volume; } if (pa_simple_write(output_device, output, sizeof(output), &pulse_error) < 0) { fprintf(stderr, "Error writing to output device: %s\n", pa_strerror(pulse_error)); to_run = 0; break; } } printf("Cleaning up...\n"); pa_simple_free(input_device); if(strlen(audio_mpx_device) != 0) pa_simple_free(mpx_device); if(strlen(audio_sca_device) != 0) pa_simple_free(sca_device); pa_simple_free(output_device); return 0; } // #region Setup Filters/Modulaltors/Oscillators Oscillator osc; init_oscillator(&osc, polar_stereo ? 31250.0 : 19000, SAMPLE_RATE); // Pilot, it's there to indicate stereo and as a refrence signal with the stereo carrier FMModulator sca_mod; init_fm_modulator(&sca_mod, sca_frequency, sca_deviation, SAMPLE_RATE); ResistorCapacitor preemp_l, preemp_r; init_preemphasis(&preemp_l, preemphasis_tau, SAMPLE_RATE); init_preemphasis(&preemp_r, preemphasis_tau, SAMPLE_RATE); // Use https://www.earlevel.com/main/2021/09/02/biquad-calculator-v3/ BiquadFilter lpf_l, lpf_r; init_lpf(&lpf_l, LPF_CUTOFF, 0.70710678f, SAMPLE_RATE); init_lpf(&lpf_r, LPF_CUTOFF, 0.70710678f, SAMPLE_RATE); Upsampler upsampler_l, upsampler_r; init_upsampler(&upsampler_l, SAMPLE_RATE/INPUT_SAMPLE_RATE, SAMPLE_RATE); init_upsampler(&upsampler_r, SAMPLE_RATE/INPUT_SAMPLE_RATE, SAMPLE_RATE); // #endregion signal(SIGINT, stop); signal(SIGTERM, stop); int pulse_error; float audio_stereo_input[BUFFER_SIZE*2]; // Input from device, interleaved stereo float mpx_in[BUFFER_SIZE] = {0}; // Input from MPX device float sca_in[BUFFER_SIZE] = {0}; // Input from SCA device float left[BUFFER_SIZE+64], right[BUFFER_SIZE+64]; // Audio, same thing as in input but uninterleaved, ai told be there could be a buffer overflow here float output[BUFFER_SIZE]; // MPX, this goes to the output while (to_run) { if (pa_simple_read(input_device, audio_stereo_input, sizeof(audio_stereo_input), &pulse_error) < 0) { fprintf(stderr, "Error reading from input device: %s\n", pa_strerror(pulse_error)); to_run = 0; break; } uninterleave(audio_stereo_input, left, right, BUFFER_SIZE*2); if(strlen(audio_mpx_device) != 0) { if (pa_simple_read(mpx_device, mpx_in, sizeof(mpx_in), &pulse_error) < 0) { fprintf(stderr, "Error reading from MPX device: %s\n", pa_strerror(pulse_error)); to_run = 0; break; } } if(strlen(audio_sca_device) != 0) { if (pa_simple_read(sca_device, sca_in, sizeof(sca_in), &pulse_error) < 0) { fprintf(stderr, "Error reading from SCA device: %s\n", pa_strerror(pulse_error)); to_run = 0; break; } } for (int i = 0; i < BUFFER_SIZE; i++) { float l_in = upsample(&upsampler_l, left[i]); float r_in = upsample(&upsampler_r, right[i]); float current_mpx_in = mpx_in[i]; float current_sca_in = sca_in[i]; float ready_l = apply_biquad(&lpf_l, l_in); float ready_r = apply_biquad(&lpf_r, r_in); ready_l = apply_preemphasis(&preemp_l, ready_l)*2; ready_r = apply_preemphasis(&preemp_r, ready_r)*2; ready_l = hard_clip(ready_l*audio_volume, clipper_threshold); ready_r = hard_clip(ready_r*audio_volume, clipper_threshold); float mono = (ready_l + ready_r) / 2.0f; // Stereo to Mono output[i] = mono*MONO_VOLUME; if(stereo == 1) { float stereo = (ready_l - ready_r) / 2.0f; // Also Stereo to Mono but a bit diffrent float stereo_carrier = get_oscillator_sin_multiplier_ni(&osc, polar_stereo ? 1 : 2); if(polar_stereo) { output[i] += ((stereo+0.2)*stereo_carrier)*STEREO_VOLUME; } else { float pilot = get_oscillator_sin_multiplier_ni(&osc, 1); output[i] += pilot*PILOT_VOLUME + (stereo*stereo_carrier)*STEREO_VOLUME; } advance_oscillator(&osc); } if(strlen(audio_mpx_device) != 0) output[i] += hard_clip(current_mpx_in, MPX_CLIPPER_THRESHOLD)*MPX_VOLUME; if(strlen(audio_sca_device) != 0) output[i] += modulate_fm(&sca_mod, hard_clip(current_sca_in, sca_clipper_threshold))*SCA_VOLUME; output[i] *= master_volume; } if (pa_simple_write(output_device, output, sizeof(output), &pulse_error) < 0) { fprintf(stderr, "Error writing to output device: %s\n", pa_strerror(pulse_error)); to_run = 0; break; } } printf("Cleaning up...\n"); pa_simple_free(input_device); if(strlen(audio_mpx_device) != 0) pa_simple_free(mpx_device); if(strlen(audio_sca_device) != 0) pa_simple_free(sca_device); pa_simple_free(output_device); return 0; }