Remove output audio thread

CHANGES.md

@@ -33,7 +33,7 @@ Intel Mac hardware is no longer supported by airspy-fmradion, although the autho
 
 * 20231215-0: Fix the following known bugs and refactor the code to streamline the functioning:
   - Bug: a hung process during the startup period before valid audio signals are coming out
-  - Bug: aisplaying `-nan` in the output level meter in broadcast FM and NBFM
+  - Bug: displaying `-nan` in the output level meter in broadcast FM and NBFM
     - The NaN is presumably generated by volk_32fc_s32f_atan2_32f() in PhaseDiscriminator::process()
     - This NaN issue was presumably the root cause of the multipath filter anomaly first fixed in 20231213-1
   - Enhancement: streamlining processing flow in the main for loop of `main()`

main.cpp

@@ -51,54 +51,12 @@
 // define this for enabling coefficient monitor functions
 // #undef COEFF_MONITOR
 
-// define this for monitoring DataBuffer queue status
-// #undef DATABUFFER_QUEUE_MONITOR
-
-#define AIRSPY_FMRADION_VERSION "20231215-0"
+#define AIRSPY_FMRADION_VERSION "20231215-direct-out"
 
 // Flag to set graceful termination
 // in process_signals()
 static std::atomic_bool stop_flag(false);
 
-// Get data from output buffer and write to output stream.
-// This code runs in a separate thread.
-static void write_output_data(AudioOutput *output, DataBuffer<Sample> *buf) {
-
-#ifdef DATABUFFER_QUEUE_MONITOR
-  unsigned int max_queue_length = 0;
-#endif // DATABUFFER_QUEUE_MONITOR
-
-  while (!stop_flag.load()) {
-
-    if (buf->pull_end_reached()) {
-      // Reached end of stream.
-      break;
-    }
-
-    // Get samples from buffer and write to output.
-    SampleVector samples = buf->pull();
-    // The output device might be closed BEFORE
-    // buf->pull() is executed, so you need to
-    // check the flag here too
-    if (!stop_flag.load()) {
-      output->write(samples);
-      if (!(*output)) {
-        fprintf(stderr, "ERROR: AudioOutput: %s\n", output->error().c_str());
-        // Setting stop_flag to true, suggested by GitHub @montgomeryb
-        stop_flag.store(true);
-      }
-    }
-
-#ifdef DATABUFFER_QUEUE_MONITOR
-    unsigned int queue_size = (unsigned int)buf->queue_size();
-    if (queue_size > max_queue_length) {
-      max_queue_length = queue_size;
-      fprintf(stderr, "Max queue length: %u\n", max_queue_length);
-    }
-#endif // DATABUFFER_QUEUE_MONITOR
-  }
-}
-
 static void usage() {
   fprintf(
       stderr,
@@ -865,12 +823,6 @@ int main(int argc, char **argv) {
   FineTuner fm_afc_finetuner((unsigned int)fm_target_rate / fm_afc_hz_step);
   float fm_afc_offset_sum = 0.0;
 
-  // If buffering enabled, start background output thread.
-  DataBuffer<Sample> output_buffer;
-  std::thread output_thread;
-  // Always use output_thread for smooth output.
-  output_thread =
-      std::thread(write_output_data, audio_output.get(), &output_buffer);
   float audio_level = 0;
   bool got_stereo = false;
 
@@ -882,26 +834,11 @@ int main(int argc, char **argv) {
 
   float if_level = 0;
 
-#ifdef DATABUFFER_QUEUE_MONITOR
-  // unsigned int nchannel = stereo ? 2 : 1;
-  bool inbuf_length_warning = false;
-  unsigned int max_source_buffer_length = 0;
-#endif // DATABUFFER_QUEUE_MONITOR
-
   ///////////////////////////////////////
   // NOTE: main processing loop from here
   ///////////////////////////////////////
   for (uint64_t block = 0; !stop_flag.load(); block++) {
 
-#ifdef DATABUFFER_QUEUE_MONITOR
-    // Check for overflow of source buffer.
-    if (!inbuf_length_warning && source_buffer.queue_size() > 10 * ifrate) {
-      fprintf(stderr, "\nWARNING: source buffer queue sizes exceeds 10 (system "
-                      "too slow)\n");
-      inbuf_length_warning = true;
-    }
-#endif // DATABUFFER_QUEUE_MONITOR
-
     // Pull next block from source buffer.
     IQSampleVector iqsamples = source_buffer.pull();
 
@@ -920,15 +857,6 @@ int main(int argc, char **argv) {
       continue;
     }
 
-#ifdef DATABUFFER_QUEUE_MONITOR
-    unsigned int source_buffer_length = source_buffer.queue_size();
-    if (source_buffer_length > max_source_buffer_length) {
-      max_source_buffer_length = source_buffer_length;
-      fprintf(stderr, "Max source buffer length: %u\n",
-              max_source_buffer_length);
-    }
-#endif // DATABUFFER_QUEUE_MONITOR
-
     double prev_block_time = block_time;
     block_time = Utility::get_time();
 
@@ -1040,7 +968,7 @@ int main(int argc, char **argv) {
     // set to zero volume if the squelch is closed.
     Utility::adjust_gain(audiosamples, if_rms >= squelch_level ? 0.5 : 0.0);
     // Write samples to output.
-    output_buffer.push(std::move(audiosamples));
+    audio_output->write(std::move(audiosamples));
 
     // Show status messages for each block if not in quiet mode.
     bool stereo_change = false;
@@ -1063,32 +991,13 @@ int main(int argc, char **argv) {
         // Show per-block statistics.
         // Add 1e-9 to log10() to prevent generating NaN
         float audio_level_db = 20 * log10(audio_level + 1e-9) + 3.01;
-#ifdef DATABUFFER_QUEUE_MONITOR
-        uint32_t quelen = (uint32_t)output_buffer.queue_size();
-#endif // DATABUFFER_QUEUE_MONITOR
 
         switch (modtype) {
         case ModType::FM:
         case ModType::NBFM:
-#ifdef DATABUFFER_QUEUE_MONITOR
-          fprintf(stderr,
-#ifdef COEFF_MONITOR
-                  // DATABUFFER_QUEUE_MONITOR && COEFF_MONITOR
-                  "blk=%11" PRIu64
-                  ":ppm=%+7.3f:IF=%+6.1fdB:AF=%+6.1fdB:qlen=%" PRIu32 "\n",
-#else
-                  // DATABUFFER_QUEUE_MONITOR && !(COEFF_MONITOR)
-                  "\rblk=%11" PRIu64
-                  ":ppm=%+7.3f:IF=%+6.1fdB:AF=%+6.1fdB:qlen=%" PRIu32,
-#endif // COEFF_MONITOR
-                  block, ppm_average.average(), if_level_db, audio_level_db,
-                  quelen);
-#else
-          // !(DATABUFFER_QUEUE_MONITOR) && !(COEFF_MONITOR)
           fprintf(stderr,
                   "\rblk=%11" PRIu64 ":ppm=%+7.3f:IF=%+6.1fdB:AF=%+6.1fdB",
                   block, ppm_average.average(), if_level_db, audio_level_db);
-#endif // DATABUFFER_QUEUE_MONITOR
           fflush(stderr);
           break;
         case ModType::AM:
@@ -1102,14 +1011,8 @@ int main(int argc, char **argv) {
           double if_agc_gain_db =
               20 * log10(am.get_if_agc_current_gain() + 1e-9);
           fprintf(stderr,
-#ifdef DATABUFFER_QUEUE_MONITOR
-                  "\rblk=%11" PRIu64
-                  ":IF=%+6.1fdB:AGC=%+6.1fdB:AF=%+6.1fdB:qlen=%" PRIu32,
-                  block, if_level_db, if_agc_gain_db, audio_level_db, quelen);
-#else
                   "\rblk=%11" PRIu64 ":IF=%+6.1fdB:AGC=%+6.1fdB:AF=%+6.1fdB",
                   block, if_level_db, if_agc_gain_db, audio_level_db);
-#endif // DATABUFFER_QUEUE_MONITOR
           fflush(stderr);
           break;
         }
@@ -1170,20 +1073,8 @@ int main(int argc, char **argv) {
   // Exit and cleanup
   fprintf(stderr, "\n");
 
-  // Terminate background audio output thread first.
-  output_buffer.push_end();
   // Close audio output.
   audio_output->output_close();
-  // Stop output thread
-  if (output_thread.joinable()) {
-    // Detach output_thread if joinable
-    output_thread.detach();
-  } else {
-    // If output_thread is not joinable,
-    // the process will halt
-    fprintf(stderr, "output_thread is not joinable\n");
-    fprintf(stderr, "You may need to kill this program with SIGKILL\n");
-  }
   // Terminate receiver thread.
   up_srcsdr->stop();
 

sfmbase/AirspySource.cpp

@@ -190,7 +190,7 @@ void AirspySource::get_device_names(std::vector<std::string> &devices) {
                    << serials[i];
       devices.push_back(devname_ostr.str());
     }
-#ifdef DEBUG_AIRSPYHFSOURCE
+#ifdef DEBUG_AIRSPYSOURCE
     std::cerr << "AirspySource::get_device_names: enumerated " << ndev
               << "device(s)" << std::endl;
 #endif

sfmbase/AmDecode.cpp

@@ -56,9 +56,9 @@ AmDecoder::AmDecoder(IQSampleCoeff &amfilter_coeff, const ModType mode)
               // reference
               ((m_mode == ModType::USB) || (m_mode == ModType::LSB) ||
                (m_mode == ModType::CW) || (m_mode == ModType::WSPR))
-                  ? 0.32
+                  ? 0.24
                   // default value
-                  : 0.8,
+                  : 0.6,
               // rate
               ((m_mode == ModType::CW) || (m_mode == ModType::WSPR))
                   ? 0.00125
@@ -72,9 +72,9 @@ AmDecoder::AmDecoder(IQSampleCoeff &amfilter_coeff, const ModType mode)
               1000000.0, // max_gain
               // rate
               ((m_mode == ModType::CW) || (m_mode == ModType::WSPR))
-                  ? 0.001
+                  ? 0.0006
                   // default value
-                  : 0.0005)
+                  : 0.0003)
 
       // fine tuner for CW pitch shifting (shift up 500Hz)
       // sampling rate: 12kHz

sfmbase/AudioOutput.cpp

@@ -229,7 +229,6 @@ bool PortAudioOutput::write(const SampleVector &samples) {
     return true;
   } else if (m_paerror == paOutputUnderflowed) {
     // This error is benign
-    // fprintf(stderr, "paOutputUnderflowed\n");
     return true;
   } else
     add_paerror("Pa_WriteStream()");

sfmbase/FmDecode.cpp

@@ -258,7 +258,6 @@ void FmDecoder::process(const IQSampleVector &samples_in, SampleVector &audio) {
       if (!done_ok) {
         // Reset the filter coefficients.
         m_multipathfilter.initialize_coefficients();
-        // fprintf(stderr, "Reset Multipath Filter coefficients\n");
         // Discard the invalid filter output, and
         // use the no-filter input after resetting the filter.
         m_samples_in_multipathfiltered = std::move(m_samples_in_after_agc);

sfmbase/MultipathFilter.cpp

@@ -57,7 +57,9 @@ MultipathFilter::MultipathFilter(unsigned int stages)
 
       // Initialize coefficient and state vectors with the size.
       ,
-      m_coeff(m_filter_order), m_state(m_filter_order) {
+      m_coeff(m_filter_order), m_state(m_filter_order),
+      // Initialize calculation error value.
+      m_error(0) {
 
   assert(stages > 0);
   for (unsigned int i = 0; i < m_filter_order; i++) {
@@ -116,7 +118,6 @@ inline void MultipathFilter::update_coeff(const IQSample result) {
                                   m_filter_order);
   volk_32f_accumulator_s32f(&state_mag_sq_sum, state_mag_sq.data(),
                             m_filter_order);
-  // fprintf(stderr, "state_mag_sq_sum = %.9g\n", state_mag_sq_sum);
 
   // Obtain the step size (dymanically computed)
   // Add offset to prevent division-by-zero error