Merge pull request #9 from el-supremo/master

Cosmetic fixes to chorus and flange examples and synth_tonesweep (ignore AudioSynthToneSweep changes)

examples/effect_chorus/effect_chorus.ino

 /*
 PROC/MEM 9/4
-Modify filter_test_f to try out a chorus effect. 
-TODO:
 
-
-140203
-  o
-I have mixed up the names "chorus" and flange". The sketches named
-chorus have, up to version 'm', actually implemented a flanger.
-From version 'o' onwards the sketches named chorus will implement
-a real chorus effect and flange will do a flanging effect.
-
-  
-  n only changed the effect parameters
-  m
-
-140201
-  l - found the problem at last using my_flange_cd_usd_c
-YES! Way back when I found I hadn't been using d_depth. Now I
-    have just discovered that I haven't been using delay_offset!!!!!
- 
-140201
-  k
-  interpolation doesn't remove the ticking
-  
-140131
-  j
->>> The lower the frequency, the less ticking.
-  - try interpolation
-140201
-  - got this restored to the way it was last night
-    and then reinstated the changes. I had a couple of
-    changes to the right channel that were incorrect or
-    weren't carried over from the left channel changes
-  
-  i
-  - don't know why but this version seems to have more "presence"
-    than previous versions.
-    The presence occurred when "sign = 1" was put in front of the left.
-    It essentially makes it a passthrough.
-    If both have "sign=1" then it is identical to passthrough
-    
-    Ticking is still not fixed
-    
-  h
-  - add sign reversal. It seems to make audio much clearer
-    BUT it hasn't got rid of the ticking noise
-  
-  g
-  - I wasn't even using delay_depth!!!!
-  
-140131
-  f
-  - added code to print the processor and memory usage every 5 seconds
-NOW the problem is to try to remove the ticking
-
-  e
-FOUND the problem with the right channel. It was also in the left channel
-but the placement of the delay line arrays made it more noticeable in the
-right channel. I was not calculating idx properly. In particular, the
-resuling index could be negative.
-
-I have shortened the delay line to only 2*AUDIO_BLOCK_SAMPLES
-
-  - removed redundancies in the update code. rewrite the block
-    instead of getting a new one
-Haven't solved the noise in the right channel yet.
-Tried duplicating right channel code to left but noise stays on the right
-
-140130
-  d
-The noise stays in the right channel even if it is calculated first
-Switching the L/R inputs doesn't switch the noise to the left channel  
-  
-  c
->> Now add a sinusoidal modulation to the offset
-    There's an awful noise in both channels but it is much louder in
-    the right channel. NOPE - it is ONLY in the right channel
-    but the audio does sound like it is working (sort of) except that it
-    is rather tinny. Maybe it needs to have the interpolation added.
-
-  b
-  - this works with clip16_6s.wav.
-    The original of this audio file was from http://www.donreiman.com/Chorus/Chorus.htm
-    I reworked it with Goldwave to make it a stereo WAV file
-    But with Rick Wakewan's Jane Seymour it seems to act more like
-    a high-pass filter.
-    
-  a
-  - removed FIR stuff and changed the name to AudioEffectChorus
-    it's basically a blank template and compiles.
-
-From: http://www.cs.cf.ac.uk/Dave/CM0268/PDF/10_CM0268_Audio_FX.pdf
-about Comb filter effects
-Effect      Delay range (ms)    Modulation
-Resonator      0 - 20            None
-Flanger        0 - 15            Sinusoidal (approx 1Hz)
-Chorus        25 - 50            None
-Echo            >50              None
+140219
+  p
 
 FMI:
 The audio board uses the following pins.
 // The delay line for left and right channels
 short delayline[CHORUS_DELAYLINE];
 
-// If this pin is grounded the FIR filter is turned which
-// makes just pass through the audio
+// If this pin is grounded the chorus is turned off
+// which makes it just pass through the audio
 // Don't use any of the pins listed above
 #define PASSTHRU_PIN 1
 
 AudioOutputI2S      audioOutput;        // audio shield: headphones & line-out
 
 // Create Audio connections between the components
-// Both channels of the audio input go to the FIR filter
+// Both channels of the audio input go to the chorus effect
 AudioConnection c1(audioInput, 0, myEffect, 0);
 AudioConnection c2(audioInput, 1, myEffect, 1);
-// both channels from the FIR filter go to the audio output
+// both channels from the chorus effect go to the audio output
 AudioConnection c3(myEffect, 0, audioOutput, 0);
 AudioConnection c4(myEffect, 1, audioOutput, 1);
 
   }
 
   // Initialize the effect
-  // address of delayline
-  // total number of samples (left AND right) in the delay line
-  // number of voices in the chorus INCLUDING the original voice
+  // - address of delayline
+  // - total number of samples (left AND right) in the delay line
+  // - number of voices in the chorus INCLUDING the original voice
   if(!myEffect.begin(delayline,CHORUS_DELAYLINE,n_chorus)) {
     Serial.println("AudioEffectChorus - begin failed");
     while(1);
     volume = n;
     audioShield.volume((float)n / 10.23);
   }
-if(1) {
+if(0) {
   if(millis() - last_time >= 5000) {
     Serial.print("Proc = ");
     Serial.print(AudioProcessorUsage());
   }
 
 }
-
-
-

examples/effect_flange/effect_flange.ino

 /*
 Change the chorus code to produce a flange effect
-
-PROC/MEM 25/4
-140204
-  d
-  - fixed the problem with user-supplied delay line
-
-140203
-  c
-  
-140203
-  b
-  - when switching to/from passthru, keep the delay line filled
-    BUT to be effective must also fix up begin and add another
-    function to allow changing to/from passthru without 
-    reinitialing everything.
-    
-I have mixed up the names "chorus" and flange". The sketches named
-chorus have, up to version 'm', actually implemented a flanger.
-From version 'o' onwards the sketches named chorus will implement
-a real chorus effect and flange will do a flanging effect.
-
-140202
-  a
-Modify filter_test_f to try out a chorus effect
-
-m + n only changed the effect parameters
-    - 
-140201
-  l - found the problem at last using my_flange_cd_usd_c
-YES! Way back when I found I hadn't been using d_depth. Now I
-    have just discovered that I haven't been using delay_offset!!!!!
- 
-140201
-  k
-  interpolation doesn't remove the ticking
-  
-140131
-  j
->>> The lower the frequency, the less ticking.
-  - try interpolation
-140201
-  - got this restored to the way it was last night
-    and then reinstated the changes. I had a couple of
-    changes to the right channel that were incorrect or
-    weren't carried over from the left channel changes
-  
-  i
-  - don't know why but this version seems to have more "presence"
-    than previous versions.
-    The presence occurred when "sign = 1" was put in front of the left.
-    It essentially makes it a passthrough.
-    If both have "sign=1" then it is identical to passthrough
-    
-    Ticking is still not fixed
-    
-  h
-  - add sign reversal. It seems to make audio much clearer
-    BUT it hasn't got rid of the ticking noise
-  
-  g
-  - I wasn't even using delay_depth!!!!
-  
-140131
-  f
-  - added code to print the processor and memory usage every 5 seconds
-NOW the problem is to try to remove the ticking
-
+140219
   e
-FOUND the problem with the right channel. It was also in the left channel
-but the placement of the delay line arrays made it more noticeable in the
-right channel. I was not calculating idx properly. In particular, the
-resuling index could be negative.
-
-I have shortened the delay line to only 2*AUDIO_BLOCK_SAMPLES
-
-  - removed redundancies in the update code. rewrite the block
-    instead of getting a new one
-Haven't solved the noise in the right channel yet.
-Tried duplicating right channel code to left but noise stays on the right
-
-140130
-  d
-The noise stays in the right channel even if it is calculated first
-Switching the L/R inputs doesn't switch the noise to the left channel  
-  
-  c
->> Now add a sinusoidal modulation to the offset
-    There's an awful noise in both channels but it is much louder in
-    the right channel. NOPE - it is ONLY in the right channel
-    but the audio does sound like it is working (sort of) except that it
-    is rather tinny. Maybe it needs to have the interpolation added.
-
-  b
-  - this works with clip16_6s.wav.
-    The original of this audio file was from http://www.donreiman.com/Chorus/Chorus.htm
-    I reworked it with Goldwave to make it a stereo WAV file
-    But with Rick Wakewan's Jane Seymour it seems to act more like
-    a high-pass filter.
-    
-  a
-  - removed FIR stuff and changed the name to AudioEffectChorus
-    it's basically a blank template and compiles.
-
-From: http://www.cs.cf.ac.uk/Dave/CM0268/PDF/10_CM0268_Audio_FX.pdf
-about Comb filter effects
-Effect      Delay range (ms)    Modulation
-Resonator      0 - 20            None
-Flanger        0 - 15            Sinusoidal (approx 1Hz)
-Chorus        25 - 50            None
-Echo            >50              None
 
 FMI:
 The audio board uses the following pins.
 // The delay line for left and right channels
 short delayline[FLANGE_DELAYLINE];
 
-// If this pin is grounded the FIR filter is turned which
-// makes just pass through the audio
+// If this pin is grounded the effect is turned off,
+// which makes it just pass through the audio
 // Don't use any of the pins listed above
 #define PASSTHRU_PIN 1
 
 AudioOutputI2S      audioOutput;        // audio shield: headphones & line-out
 
 // Create Audio connections between the components
-// Both channels of the audio input go to the FIR filter
+// Both channels of the audio input go to the flange effect
 AudioConnection c1(audioInput, 0, myEffect, 0);
 AudioConnection c2(audioInput, 1, myEffect, 1);
-// both channels from the FIR filter go to the audio output
+// both channels from the flange effect go to the audio output
 AudioConnection c3(myEffect, 0, audioOutput, 0);
 AudioConnection c4(myEffect, 1, audioOutput, 1);
 
 double s_freq = .0625;
 */
 
-//12 - good with Eric Clapton Unplugged
 /*
+//12 - good with Eric Clapton Unplugged
 int s_idx = 3*FLANGE_DELAY_LENGTH/4;
 int s_depth = FLANGE_DELAY_LENGTH/8;
 double s_freq = .0625;
 */
+
+/*
+// Real flange effect! delay line is 2*
+int s_idx = 2*FLANGE_DELAY_LENGTH/4;
+int s_depth = FLANGE_DELAY_LENGTH/4;
+double s_freq = 2;
+*/
+
+/* 2 - 
+int s_idx = 2*FLANGE_DELAY_LENGTH/4;
+int s_depth = FLANGE_DELAY_LENGTH/8;
+double s_freq = 4;
+*/
+/*
+// 4
+int s_idx = FLANGE_DELAY_LENGTH/4;
+int s_depth = FLANGE_DELAY_LENGTH/4;
+double s_freq = .25;
+*/
+// 4
 int s_idx = FLANGE_DELAY_LENGTH/4;
 int s_depth = FLANGE_DELAY_LENGTH/4;
 double s_freq = .5;
-
 void setup() {
   
   Serial.begin(9600);
   }
 
   // Set up the flange effect
-  // address of delayline
-  // total number of samples (left AND right) in the delay line
-  // Index (in samples) into the delay line for the added voice
-  // Depth of the flange effect
-  // frequency of the flange effect
+  // - address of delayline
+  // - total number of samples (left AND right) in the delay line
+  // - Index (in samples) into the delay line for the added voice
+  // - Depth of the flange effect
+  // - frequency of the flange effect
   myEffect.begin(delayline,FLANGE_DELAYLINE,s_idx,s_depth,s_freq);
 
   // I want output on the line out too
     volume = n;
     audioShield.volume((float)n / 10.23);
   }
-if(1) {
+if(0) {
   if(millis() - last_time >= 5000) {
     Serial.print("Proc = ");
     Serial.print(AudioProcessorUsage());
   b_passthru.update();
  
   // If the passthru button is pushed, save the current
-  // filter index and then switch the filter to passthru
+  // filter index and then switch the effect to passthru
   if(b_passthru.fallingEdge()) {
     myEffect.modify(DELAY_PASSTHRU,0,0);
   }
   }
 
 }
-
-
-
-

synth_tonesweep.cpp

 #include "arm_math.h"
 
 
-// TODO: this object should be renamed to AudioSynthToneSweep
+
 
 /******************************************************************/
 
-//                A u d i o T o n e S w e e p
+//                A u d i o S y n t h T o n e S w e e p
 // Written by Pete (El Supremo) Feb 2014
 
 
   return(sweep_busy);
 }
 
-static int b_count = 0; // TODO: what's this for?
 
 void AudioSynthToneSweep::update(void)
 {

synth_tonesweep.h

 
 #include "AudioStream.h"
 
-//                A u d i o T o n e S w e e p
+//                A u d i o S y n t h T o n e S w e e p
 // Written by Pete (El Supremo) Feb 2014
 
 class AudioSynthToneSweep : public AudioStream