Merge pull request #53 from newdigate/feature/play_start

Feature: play start option
newdigate · Feb 26, 2023 · f9e1565 · f9e1565
2 parents 04605a9 + 3fa59fc
commit f9e1565
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Showing 6 changed files with 82 additions and 22 deletions.
diff --git a/README.md b/README.md
@@ -16,11 +16,21 @@ play 16-bit PCM raw or wav audio samples at variable playback rates on teensy
   * [sd classes on wikipedia](https://en.wikipedia.org/wiki/SD_card#cite_ref-93) 
 
 ## updates
+* 26/02/2022: v1.0.16:
+  * add option for starting sample at begining or at loop start
+  ``` c
+  typedef enum play_start {
+      play_start_sample,
+      play_start_loop,
+  };
+
+  wave.setPlayStart(play_start::play_start_loop); 
+  ```
 * 26/02/2022: v1.0.15:
   * added support for dual playback head for seemless looping
     * enable dual playback using linear crossfading
     * set crossfade duration in number of samples
-  ```
+  ``` c
         AudioPlaySdResmp         wave;      
         wave.setUseDualPlaybackHead(true);
         wave.setCrossfadeDurationInSamples(1000);

diff --git a/library.json b/library.json
@@ -5,7 +5,7 @@
     "keywords": "sound, audio, sample, resample, pitch, interpolation, legrange, sampler, playback, speed, loop",
     "description": "Teensy Variable Playback",
     "url": "https://github.com/newdigate/teensy-variable-playback",
-    "version": "1.0.15",
+    "version": "1.0.16",
     "export": {
       "exclude": [
         ".vscode",

diff --git a/library.properties b/library.properties
@@ -1,5 +1,5 @@
 name=TeensyVariablePlayback
-version=1.0.15
+version=1.0.16
 author=Nic Newdigate
 maintainer=Nic Newdigate
 sentence=Play samples at variable pitch using Teensy Audio Library

diff --git a/src/ResamplingReader.h b/src/ResamplingReader.h
@@ -29,7 +29,10 @@ class ResamplingReader {
         }
         _playing = false;
         _crossfade = 0.0;
-        _bufferPosition1 = _header_offset;
+        if (_play_start == play_start::play_start_sample)
+            _bufferPosition1 = _header_offset;
+        else
+            _bufferPosition1 = _loop_start;
         _file_size = 0;
     }
 
@@ -190,11 +193,12 @@ class ResamplingReader {
                         {
                             if (_playbackRate >= 0.0) {
                                 _bufferPosition1 = _loop_finish - _numChannels;
-                                //printf("switching to reverse playback...\n");
                             }
                             else {
-                                _bufferPosition1 = _header_offset;
-                                //printf("switching to forward playback...\n");
+                                if (_play_start == play_start::play_start_sample)
+                                    _bufferPosition1 = _header_offset;
+                                else
+                                    _bufferPosition1 = _loop_start;
                             }
                             _playbackRate = -_playbackRate;
                             break;
@@ -223,9 +227,14 @@ class ResamplingReader {
                 if (_bufferPosition1 >=  _loop_finish )
                     return false;
             } else if (_playbackRate < 0) {
-                // reverse playback    
-                if (_bufferPosition1 < _header_offset)
-                    return false;
+                // reverse playback
+                if (_play_start == play_start::play_start_sample) {
+                    if (_bufferPosition1 < _header_offset)
+                        return false;
+                } else {
+                    if (_bufferPosition1 < _loop_start)
+                        return false;    
+                }
             }
         } else {
             if (_playbackRate >= 0.0) {
@@ -427,9 +436,36 @@ class ResamplingReader {
     void setPlaybackRate(double f) {
         _playbackRate = f;
         if (!_useDualPlaybackHead) {
-            if (f < 0.0 && _bufferPosition1 == 0) {
-                //_file.seek(_file_size);
-                _bufferPosition1 = _file_size/2 - _numChannels;
+            if (f < 0.0) {
+                if  (_bufferPosition1 <= _header_offset) {
+                    if (_play_start == play_start::play_start_sample)
+                        _bufferPosition1 = _file_size/2 - _numChannels;
+                    else
+                        _bufferPosition1 = _loop_finish - _numChannels;
+                } 
+            } else {
+                if (f >= 0.0 && _bufferPosition1 < _header_offset) {
+                    if (_play_start == play_start::play_start_sample) 
+                        _bufferPosition1 = _header_offset;
+                    else
+                        _bufferPosition1 = _loop_start;
+                }
+            }
+        } else { 
+            // _useDualPlaybackHead == true 
+            if (_crossfade == 0.0) {
+                if (f < 0.0) { 
+                    if( _bufferPosition1 <= _header_offset) {
+                        if (_play_start == play_start::play_start_sample)
+                            _bufferPosition1 = _file_size/2 - _numChannels;
+                        else
+                            _bufferPosition1 = _loop_finish - _numChannels;
+                    }
+                } else {
+                    if (f >= 0.0 && _bufferPosition1 < _header_offset) {
+                        _bufferPosition1 = _header_offset;
+                    }
+                }
             }
         }
     }
@@ -465,10 +501,16 @@ class ResamplingReader {
         _numInterpolationPoints = 0;
         if (_playbackRate > 0.0) {
             // forward playabck - set _file_offset to first audio block in file
-            _bufferPosition1 = _header_offset;
+            if (_play_start == play_start::play_start_sample)
+                _bufferPosition1 = _header_offset;
+            else
+                _bufferPosition1 = _loop_start;
         } else {
             // reverse playback - forward _file_offset to last audio block in file
-            _bufferPosition1 = _loop_finish - _numChannels;
+            if (_play_start == play_start::play_start_sample)
+                _bufferPosition1 = _file_size/2 - _numChannels;
+            else
+                _bufferPosition1 = _loop_finish - _numChannels;
         }
         _crossfade = 0.0;
     }
@@ -510,14 +552,12 @@ class ResamplingReader {
 
     void setHeaderSizeInBytes(uint32_t headerSizeInBytes) {
         _header_offset = headerSizeInBytes / 2;
-        if (_bufferPosition1 < _header_offset) {
-            if (_playbackRate >= 0) {
-                _bufferPosition1 = _header_offset;
-            } else
-                _bufferPosition1 = _loop_finish - _numChannels;
-        }
     }
 
+    void setPlayStart(play_start start) {
+        _play_start = start;
+    }
+
     #define B2M (uint32_t)((double)4294967296000.0 / AUDIO_SAMPLE_RATE_EXACT / 2.0) // 97352592
     uint32_t positionMillis()
     {
@@ -537,7 +577,8 @@ class ResamplingReader {
 
     double _playbackRate = 1.0;
     double _remainder = 0.0;
-    loop_type _loopType = looptype_none;
+    loop_type _loopType = loop_type::looptype_none;
+    play_start _play_start = play_start::play_start_sample;
     int _bufferPosition1 = 0;
     int _bufferPosition2 = 0;
     double _crossfade = 0.0;

diff --git a/src/loop_type.h b/src/loop_type.h
@@ -11,4 +11,9 @@ typedef enum loop_type {
     looptype_pingpong
 } loop_type;
 
+typedef enum play_start {
+    play_start_sample,
+    play_start_loop,
+} play_start;
+
 #endif //TEENSY_RESAMPLING_LOOP_TYPE_H
diff --git a/src/playresmp.h b/src/playresmp.h
@@ -78,6 +78,10 @@ class AudioPlayResmp : public AudioStream
             reader->setCrossfadeDurationInSamples(crossfadeDurationInSamples);
         }
 
+        void setPlayStart(play_start start) {
+            reader->setPlayStart(start);
+        }
+
         void enableInterpolation(bool enable) {
             if (enable)
                 reader->setInterpolationType(ResampleInterpolationType::resampleinterpolation_quadratic);