Recording is now writing playable .WAV files

src/audio/AudioFileWAV.cpp

@@ -2,7 +2,49 @@
 // SPDX-License-Identifier: GPL-2.0+
 
 #include "AudioFileWAV.h"
-// #include "WavFileFormatHandlerStuff.h"
+
+
+// Simple endian io read/write handling from 
+// http://www.cplusplus.com/forum/beginner/31584/#msg171056
+namespace little_endian_io
+{
+    template <typename Word>
+    std::ostream& write_word(std::ostream& outs, Word value, unsigned size = sizeof(Word)) {
+        for (; size; --size, value >>= 8) {
+            outs.put(static_cast <char> (value & 0xFF));
+        }
+        return outs;
+    }
+
+    template <typename Word>
+    std::istream& read_word(std::istream& ins, Word& value, unsigned size = sizeof(Word)) {
+        for (unsigned n = 0, value = 0; n < size; ++n) {
+            value |= ins.get() << (8 * n);
+        }
+        return ins;
+    }
+}
+
+namespace big_endian_io
+{
+    template <typename Word>
+    std::ostream& write_word(std::ostream& outs, Word value, unsigned size = sizeof(Word)) {
+        while (size) {
+            outs.put(static_cast <char> ((value >> (8 * --size)) & 0xFF));
+        }
+        return outs;
+    }
+
+    template <typename Word>
+    std::istream& read_word(std::istream& ins, Word& value, unsigned size = sizeof(Word)) {
+        for (value = 0; size; --size) {
+            value = (value << 8) | ins.get();
+        }
+        return ins;
+    }
+}
+
+using namespace little_endian_io;
 
 AudioFileWAV::AudioFileWAV() : AudioFile() {
 }
@@ -27,12 +69,43 @@ bool AudioFileWAV::writeToFile(AudioThreadInputPtr input)
         suffix = "";
         std::string ofName = getOutputFileName();
                 
-        // Check if file exists, sequence the suffix?
+        // TODO: Check if file exists, sequence the suffix
+        outputFileStream.open(ofName.c_str(), std::ios::binary);
 
-        outputFileStream.open(ofName.c_str(), std::ios::out | std::ios::binary);
+        // Based on simple wav file output code from
+        // http://www.cplusplus.com/forum/beginner/166954/
+
+        // Write the wav file headers
+        outputFileStream << "RIFF----WAVEfmt "; // (chunk size to be filled in later)
+        write_word(outputFileStream, 16, 4); // no extension data
+        write_word(outputFileStream, 1, 2); // PCM - integer samples
+        write_word(outputFileStream, input->channels, 2); // channels
+        write_word(outputFileStream, input->sampleRate, 4); // samples per second (Hz)
+        write_word(outputFileStream, (input->sampleRate * 16 * input->channels) / 8, 4); // (Sample Rate * BitsPerSample * Channels) / 8
+        write_word(outputFileStream, input->channels * 2, 2); // data block size (size of integer samples, one for each channel, in bytes)
+        write_word(outputFileStream, 16, 2); // number of bits per sample (use a multiple of 8)
+
+        // Write the data chunk header
+        dataChunkPos = outputFileStream.tellp();
+        outputFileStream << "data----";  // (chunk size to be filled in later)
     }
 
-    // write input data to wav file
+    // Prevent clipping
+    float intScale = (input->peak < 1.0) ? 32767.0f : (32767.0f / input->peak);
+
+    if (input->channels == 1) {
+        for (int i = 0, iMax = input->data.size(); i < iMax; i++) {
+            write_word(outputFileStream, int(input->data[i] * intScale), 2);
+        }
+    }
+    else if (input->channels == 2) {
+        for (int i = 0, iMax = input->data.size() / 2; i < iMax; i++) {
+            write_word(outputFileStream, int(input->data[i * 2] * intScale), 2);
+            write_word(outputFileStream, int(input->data[i * 2 + 1] * intScale), 2);
+        }
+    }
+
+    // TODO: Periodically update the RIFF/data chunk size in case of crash?
 
     return true;
 }
@@ -40,6 +113,16 @@ bool AudioFileWAV::writeToFile(AudioThreadInputPtr input)
 bool AudioFileWAV::closeFile()
 {
     if (outputFileStream.is_open()) {
+        size_t file_length = outputFileStream.tellp();
+
+        // Fix the data chunk header to contain the data size
+        outputFileStream.seekp(dataChunkPos + 4);
+        write_word(outputFileStream, file_length - dataChunkPos + 8);
+
+        // Fix the file header to contain the proper RIFF chunk size, which is (file size - 8) bytes
+        outputFileStream.seekp(0 + 4);
+        write_word(outputFileStream, file_length - 8, 4);
+
         outputFileStream.close();
     }
 

src/audio/AudioFileWAV.h

@@ -22,5 +22,5 @@ public:
 protected:
     std::ofstream outputFileStream;
     std::string suffix;
-
+    size_t dataChunkPos;
 };