Refactor the engine to process samples in the range of [-1.0, 1.0]. Fixes Bug #1204039.

* Move Vinyl Control pre-amp to VinylControlXwax (no longer affects
  microphone/passthrough).

* Switch PortAudio input sample format to paFloat32.

* Remove SHRT_MAX conversions on input and output samples.

* Update VUMeters, clipping, and dithering code to deal with the new ranges.

* Clean up EngineMicrophone/EnginePassthrough/EngineDeck handling of inputs.

* Update tests to deal with the new sample ranges.

This does not change SoundSource. SoundSources still read 16-bit samples and we
simply divide by SHRT_MAX in AnalyserQueue and CachingReaderWorker. A future
performance improvement can remove this and use the native decoder API to
request normalized samples directly.

1 files changed, 18 insertions, 4 deletions

diff --git a/src/vinylcontrol/vinylcontrolxwax.cpp b/src/vinylcontrol/vinylcontrolxwax.cpp
index 2a8bbfd57f..1ae09a83b4 100644
--- a/src/vinylcontrol/vinylcontrolxwax.cpp
+++ b/src/vinylcontrol/vinylcontrolxwax.cpp
@@ -187,15 +187,29 @@ bool VinylControlXwax::writeQualityReport(VinylSignalQualityReport* pReport) {
 }
 
 
-void VinylControlXwax::analyzeSamples(const short *samples, size_t nFrames)
-{
+void VinylControlXwax::analyzeSamples(CSAMPLE* pSamples, size_t nFrames) {
     ScopedTimer t("VinylControlXwax::analyzeSamples");
+    CSAMPLE gain = m_pVinylControlInputGain->get();
+    const int kChannels = 2;
+
+    // Convert CSAMPLE samples to shorts, preventing overflow.
+    for (int i = 0; i < nFrames * kChannels; ++i) {
+        double sample = pSamples[i] * gain * SHRT_MAX;
+
+        if (sample > SHRT_MAX) {
+            m_pWorkBuffer[i] = SHRT_MAX;
+        } else if (sample < SHRT_MIN) {
+            m_pWorkBuffer[i] = SHRT_MIN;
+        } else {
+            m_pWorkBuffer[i] = static_cast<short>(sample);
+        }
+    }
 
     // Submit the samples to the xwax timecode processor. The size argument is
     // in stereo frames.
-    timecoder_submit(&timecoder, samples, nFrames);
+    timecoder_submit(&timecoder, m_pWorkBuffer, nFrames);
 
-    bool bHaveSignal = fabs((float)samples[0]) + fabs((float)samples[1]) > MIN_SIGNAL;
+    bool bHaveSignal = fabs(pSamples[0]) + fabs(pSamples[1]) > MIN_SIGNAL;
     //qDebug() << "signal?" << bHaveSignal;
 
     //TODO: Move all these config object get*() calls to an "updatePrefs()" function,