Add WAV file reader.

examples/Beginner/Audio_Playback/Audio_Playback.ino

@@ -6,154 +6,79 @@
 */
 
 #include <Arduino_AdvancedAnalog.h>
-
 #include <Arduino_USBHostMbed5.h>
-
 #include <DigitalOut.h>
 #include <FATFileSystem.h>
 
-AdvancedDAC dac1(A12);
-
 USBHostMSD msd;
 mbed::FATFileSystem usb("USB_DRIVE");
 
-FILE * file = nullptr;
-int sample_size = 0;
-int samples_count = 0;
-
+WavReader wavreader;
+AdvancedDAC dac1(A12);
+#define N_SAMPLES   (512)
 
-void setup()
-{
+void setup() {
   Serial.begin(115200);
-  while (!Serial);
+  while (!Serial) {
+  }
 
-  /* Enable power for HOST USB connector. */
+  // Enable power for HOST USB connector.
   pinMode(PA_15, OUTPUT);
   digitalWrite(PA_15, HIGH);
 
-  Serial.println("Please connect a USB stick to the GIGA's USB port ...");
-  while (!msd.connect()) delay(100);
+  Serial.println("Please connect a USB stick to the USB host port ...");
+  while (!msd.connect()) {
+    delay(100);
+  }
 
   Serial.println("Mounting USB device ...");
   int const rc_mount = usb.mount(&msd);
-  if (rc_mount)
-  {
+  if (rc_mount) {
     Serial.print("Error mounting USB device ");
     Serial.println(rc_mount);
-    return;
+    while (1);
   }
 
   Serial.println("Opening audio file ...");
-
-  /* 16-bit PCM Mono 16kHz realigned noise reduction */
-  file = fopen("/USB_DRIVE/AUDIO_SAMPLE.wav", "rb");
-  if (file == nullptr)
-  {
-    Serial.print("Error opening audio file: ");
-    Serial.println(strerror(errno));
-    return;
+  if (!wavreader.begin("/USB_DRIVE/AUDIO_SAMPLE.wav", N_SAMPLES, 1, false)) {
+      Serial.print("Error opening audio file: ");
+      while (1);
   }
 
-  Serial.println("Reading audio header ...");
-  struct wav_header_t
-  {
-    char chunkID[4]; //"RIFF" = 0x46464952
-    unsigned long chunkSize; //28 [+ sizeof(wExtraFormatBytes) + wExtraFormatBytes] + sum(sizeof(chunk.id) + sizeof(chunk.size) + chunk.size)
-    char format[4]; //"WAVE" = 0x45564157
-    char subchunk1ID[4]; //"fmt " = 0x20746D66
-    unsigned long subchunk1Size; //16 [+ sizeof(wExtraFormatBytes) + wExtraFormatBytes]
-    unsigned short audioFormat;
-    unsigned short numChannels;
-    unsigned long sampleRate;
-    unsigned long byteRate;
-    unsigned short blockAlign;
-    unsigned short bitsPerSample;
-  };
-
-  wav_header_t header;
-  fread(&header, sizeof(header), 1, file);
-
-  Serial.println("WAV File Header read:");
   char msg[64] = {0};
-  snprintf(msg, sizeof(msg), "File Type: %s", header.chunkID);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "File Size: %ld", header.chunkSize);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "WAV Marker: %s", header.format);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Format Name: %s", header.subchunk1ID);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Format Length: %ld", header.subchunk1Size);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Format Type: %hd", header.audioFormat);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Number of Channels: %hd", header.numChannels);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Sample Rate: %ld", header.sampleRate);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Sample Rate * Bits/Sample * Channels / 8: %ld", header.byteRate);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Bits per Sample * Channels / 8: %hd", header.blockAlign);
-  Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Bits per Sample: %hd", header.bitsPerSample);
-  Serial.println(msg);
-
-  /* Find the data section of the WAV file. */
-  struct chunk_t
-  {
-    char ID[4];
-    unsigned long size;
-  };
-
-  chunk_t chunk;
-  snprintf(msg, sizeof(msg), "id\t" "size");
-  Serial.println(msg);
-  /* Find data chunk. */
-  while (true)
-  {
-    fread(&chunk, sizeof(chunk), 1, file);
-    snprintf(msg, sizeof(msg), "%c%c%c%c\t" "%li", chunk.ID[0], chunk.ID[1], chunk.ID[2], chunk.ID[3], chunk.size);
-    Serial.println(msg);
-    if (*(unsigned int *) &chunk.ID == 0x61746164)
-      break;
-    /* Skip chunk data bytes. */
-    fseek(file, chunk.size, SEEK_CUR);
-  }
-
-  /* Determine number of samples. */
-  sample_size = header.bitsPerSample / 8;
-  samples_count = chunk.size * 8 / header.bitsPerSample;
-  snprintf(msg, sizeof(msg), "Sample size = %i", sample_size); Serial.println(msg);
-  snprintf(msg, sizeof(msg), "Samples count = %i", samples_count); Serial.println(msg);
+  snprintf(msg, sizeof(msg), "Number of Channels: %hd", wavreader.channels()); Serial.println(msg);
+  snprintf(msg, sizeof(msg), "Sample Rate: %ld", wavreader.sample_rate()); Serial.println(msg);
+  snprintf(msg, sizeof(msg), "Bits per Sample: %hd", wavreader.resolution()); Serial.println(msg);
+  snprintf(msg, sizeof(msg), "Number of Samples = %i", wavreader.sample_count()); Serial.println(msg);
 
-  /* Configure the advanced DAC. */
-  if (!dac1.begin(AN_RESOLUTION_12, header.sampleRate, 256, 16))
-  {
+  // Configure and start the DAC.
+  if (!dac1.begin(AN_RESOLUTION_12, wavreader.sample_rate(), N_SAMPLES, 32)) {
     Serial.println("Failed to start DAC1 !");
-    return;
+    while (1);
   }
 }
 
-void loop()
-{
-  if (dac1.available() && !feof(file))
-  {
-    /* Read data from file. */
-    uint16_t sample_data[256] = {0};
-    fread(sample_data, sample_size, 256, file);
-
-    /* Get a free buffer for writing. */
-    SampleBuffer buf = dac1.dequeue();
-
-    /* Write data to buffer. */
-    for (size_t i = 0; i < buf.size(); i++)
-    {
-      /* Scale down to 12 bit. */
-      uint16_t const dac_val = ((static_cast<unsigned int>(sample_data[i])+32768)>>4) & 0x0fff;
-      buf[i] = dac_val;
+void loop() {
+  if (dac1.available() && wavreader.available()) {
+    // Get a free buffer for writing.
+    SampleBuffer dacbuf = dac1.dequeue();
+
+    // Read a samples buffer from the wav file.
+    SampleBuffer pcmbuf = wavreader.read();
+
+    // Process and write samples to the DAC buffer.
+    for (size_t i=0; i<N_SAMPLES; i++) {
+      // Map the samples to positive range and down scale to 12-bit.
+      if (wavreader.channels() == 1) {
+        dacbuf[i] = ((unsigned int) ((int16_t) pcmbuf[i] + 32768)) >> 4;
+      } else {
+        // If the file has two channels set the average.
+        dacbuf[i] = ((unsigned int) ((((int16_t) pcmbuf[(i * 2)] + (int16_t) pcmbuf[(i * 2) + 1]) / 2) + 32768)) >> 4;
+      }
     }
 
-    /* Write the buffer to DAC. */
-    dac1.write(buf);
+    // Write the buffer to DAC.
+    dac1.write(dacbuf);
+    pcmbuf.release();
   }
 }

src/Arduino_AdvancedAnalog.h

@@ -26,5 +26,6 @@
 
 #include "AdvancedADC.h"
 #include "AdvancedDAC.h"
+#include "WavReader.h"
 
 #endif /* ADVANCEDANALOGREDUX_ARDUINO_ADVANCEDANALOG_H */

src/WavReader.cpp

@@ -0,0 +1,109 @@
+/*
+  This file is part of the Arduino_AdvancedAnalog library.
+  Copyright (c) 2024 Arduino SA. All rights reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include "Arduino.h"
+#include "WavReader.h"
+
+WavReader::~WavReader() {
+    stop();
+}
+
+int WavReader::begin(const char *path, size_t n_samples, size_t n_buffers, bool loop) {
+    this->loop = loop;
+
+    if ((file = fopen(path, "rb")) == nullptr) {
+        return 0;
+    }
+
+    // Read file header
+    fread(&header, sizeof(header), 1, file);
+
+    // Add more sanity checks if needed.
+    if (memcmp(header.chunk_id, "RIFF", 4) != 0 ||
+        memcmp(header.format, "WAVEfmt", 7) != 0 ||
+        ((sizeof(Sample) * 8) < header.bits_per_sample) ||
+        (n_samples * header.num_channels) > sample_count()) {
+        stop();
+        return 0;
+    }
+
+    // Allocate the DMA buffer pool.
+    pool = new DMABufferPool<Sample>(n_samples, header.num_channels, n_buffers);
+    if (pool == nullptr) {
+        stop();
+        return 0;
+    }
+    return 1;
+}
+
+void WavReader::stop() {
+    if (file) {
+        fclose(file);
+    }
+    if (pool) {
+        delete pool;
+    }
+    pool = nullptr;
+    file = nullptr;
+}
+
+bool WavReader::available() {
+    if (file != nullptr && pool != nullptr) {
+        return pool->writable();
+    }
+    return false;
+}
+
+DMABuffer<Sample> &WavReader::read() {
+    while (!available()) {
+        __WFI();
+    }
+
+    DMABuffer<Sample> *buf = pool->allocate();
+    size_t offset = 0;
+    Sample *rawbuf = buf->data();
+    size_t n_samples = buf->size();
+
+    while (offset < n_samples) {
+        offset += fread(&rawbuf[offset], sizeof(Sample), n_samples - offset, file);
+        if (offset < n_samples) {
+            if (loop) {
+                rewind();
+            } else {
+                for (size_t i=offset; i<n_samples; i++) {
+                    rawbuf[i] = 0;
+                }
+                fclose(file);
+                file = nullptr;
+                break;
+            }
+        }
+    }
+    return *buf;
+}
+
+int WavReader::rewind() {
+    if (file == nullptr) {
+        return 0;
+    }
+    if (fseek(file, sizeof(WavHeader), SEEK_SET) == -1) {
+        return 0;
+    }
+    return 1;
+}

src/WavReader.h

@@ -0,0 +1,74 @@
+/*
+  This file is part of the Arduino_AdvancedAnalog library.
+  Copyright (c) 2024 Arduino SA. All rights reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include "AdvancedAnalog.h"
+
+#ifndef ARDUINO_WAV_READER_H_
+#define ARDUINO_WAV_READER_H_
+
+class WavReader {
+    typedef struct {
+        char chunk_id[4];
+        unsigned int chunk_size;
+        char format[4];
+        char subchunk1_id[4];
+        unsigned int subchunk1_size;
+        unsigned short audio_format;
+        unsigned short num_channels;
+        unsigned int sample_rate;
+        unsigned int byte_rate;
+        unsigned short block_align;
+        unsigned short bits_per_sample;
+        char subchunk2_id[4];
+        unsigned int subchunk2_size;
+    } WavHeader;
+
+    private:
+        FILE *file;
+        bool loop;
+        WavHeader header;
+        DMABufferPool<Sample> *pool;
+
+    public:
+        WavReader(): file(nullptr), loop(false), pool(nullptr) {
+        }
+        ~WavReader();
+        size_t channels() {
+            return header.num_channels;
+        }
+
+        size_t resolution() {
+            return header.bits_per_sample;
+        }
+
+        size_t sample_rate() {
+            return header.sample_rate;
+        }
+
+        size_t sample_count() {
+            return (header.subchunk2_size * 8) / header.bits_per_sample;
+        }
+
+        int begin(const char *path, size_t n_samples, size_t n_buffers, bool loop=false);
+        void stop();
+        bool available();
+        SampleBuffer read();
+        int rewind();
+};
+#endif /* ARDUINO_WAV_READER_H_ */