Add wav file writer

1 files changed, 268 insertions, 0 deletions

diff --git a/src/wavfile.cpp b/src/wavfile.cpp
new file mode 100644
index 0000000..dbc1e13
--- /dev/null
+++ b/src/wavfile.cpp
@@ -0,0 +1,268 @@
+/* ------------------------------------------------------------------
+ * Copyright (C) 2009 Martin Storsjo
+ * Copyright (C) 2017 Matthias P. Braendli
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ * -------------------------------------------------------------------
+ */
+
+#include "wavfile.h"
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <cstdint>
+#include <stdexcept>
+
+#define TAG(a, b, c, d) (((a) << 24) | ((b) << 16) | ((c) << 8) | (d))
+
+struct wav_reader {
+    FILE *wav;
+    uint32_t data_length;
+
+    int format;
+    int sample_rate;
+    int bits_per_sample;
+    int channels;
+    int byte_rate;
+    int block_align;
+
+    int streamed;
+};
+
+static uint32_t read_tag(struct wav_reader* wr) {
+    uint32_t tag = 0;
+    tag = (tag << 8) | fgetc(wr->wav);
+    tag = (tag << 8) | fgetc(wr->wav);
+    tag = (tag << 8) | fgetc(wr->wav);
+    tag = (tag << 8) | fgetc(wr->wav);
+    return tag;
+}
+
+static uint32_t read_int32(struct wav_reader* wr) {
+    uint32_t value = 0;
+    value |= fgetc(wr->wav) <<  0;
+    value |= fgetc(wr->wav) <<  8;
+    value |= fgetc(wr->wav) << 16;
+    value |= fgetc(wr->wav) << 24;
+    return value;
+}
+
+static uint16_t read_int16(struct wav_reader* wr) {
+    uint16_t value = 0;
+    value |= fgetc(wr->wav) << 0;
+    value |= fgetc(wr->wav) << 8;
+    return value;
+}
+
+static void skip(FILE *f, int n) {
+    int i;
+    for (i = 0; i < n; i++)
+        fgetc(f);
+}
+
+void* wav_read_open(const char *filename) {
+    struct wav_reader* wr = (struct wav_reader*) malloc(sizeof(*wr));
+    long data_pos = 0;
+    memset(wr, 0, sizeof(*wr));
+
+    if (!strcmp(filename, "-"))
+        wr->wav = stdin;
+    else
+        wr->wav = fopen(filename, "rb");
+    if (wr->wav == NULL) {
+        free(wr);
+        return NULL;
+    }
+
+    while (1) {
+        uint32_t tag, tag2, length;
+        tag = read_tag(wr);
+        if (feof(wr->wav))
+            break;
+        length = read_int32(wr);
+        if (!length || length >= 0x7fff0000) {
+            wr->streamed = 1;
+            length = ~0;
+        }
+        if (tag != TAG('R', 'I', 'F', 'F') || length < 4) {
+            fseek(wr->wav, length, SEEK_CUR);
+            continue;
+        }
+        tag2 = read_tag(wr);
+        length -= 4;
+        if (tag2 != TAG('W', 'A', 'V', 'E')) {
+            fseek(wr->wav, length, SEEK_CUR);
+            continue;
+        }
+        // RIFF chunk found, iterate through it
+        while (length >= 8) {
+            uint32_t subtag, sublength;
+            subtag = read_tag(wr);
+            if (feof(wr->wav))
+                break;
+            sublength = read_int32(wr);
+            length -= 8;
+            if (length < sublength)
+                break;
+            if (subtag == TAG('f', 'm', 't', ' ')) {
+                if (sublength < 16) {
+                    // Insufficient data for 'fmt '
+                    break;
+                }
+                wr->format          = read_int16(wr);
+                wr->channels        = read_int16(wr);
+                wr->sample_rate     = read_int32(wr);
+                wr->byte_rate       = read_int32(wr);
+                wr->block_align     = read_int16(wr);
+                wr->bits_per_sample = read_int16(wr);
+                if (wr->format == 0xfffe) {
+                    if (sublength < 28) {
+                        // Insufficient data for waveformatex
+                        break;
+                    }
+                    skip(wr->wav, 8);
+                    wr->format = read_int32(wr);
+                    skip(wr->wav, sublength - 28);
+                } else {
+                    skip(wr->wav, sublength - 16);
+                }
+            } else if (subtag == TAG('d', 'a', 't', 'a')) {
+                data_pos = ftell(wr->wav);
+                wr->data_length = sublength;
+                if (!wr->data_length || wr->streamed) {
+                    wr->streamed = 1;
+                    return wr;
+                }
+                fseek(wr->wav, sublength, SEEK_CUR);
+            } else {
+                skip(wr->wav, sublength);
+            }
+            length -= sublength;
+        }
+        if (length > 0) {
+            // Bad chunk?
+            fseek(wr->wav, length, SEEK_CUR);
+        }
+    }
+    fseek(wr->wav, data_pos, SEEK_SET);
+    return wr;
+}
+
+void wav_read_close(void* obj) {
+    struct wav_reader* wr = (struct wav_reader*) obj;
+    if (wr->wav != stdin)
+        fclose(wr->wav);
+    free(wr);
+}
+
+int wav_get_header(void* obj, int* format, int* channels, int* sample_rate, int* bits_per_sample, unsigned int* data_length) {
+    struct wav_reader* wr = (struct wav_reader*) obj;
+    if (format)
+        *format = wr->format;
+    if (channels)
+        *channels = wr->channels;
+    if (sample_rate)
+        *sample_rate = wr->sample_rate;
+    if (bits_per_sample)
+        *bits_per_sample = wr->bits_per_sample;
+    if (data_length)
+        *data_length = wr->data_length;
+    return wr->format && wr->sample_rate;
+}
+
+int wav_read_data(void* obj, unsigned char* data, unsigned int length) {
+    struct wav_reader* wr = (struct wav_reader*) obj;
+    int n;
+    if (wr->wav == NULL)
+        return -1;
+    if (length > wr->data_length && !wr->streamed)
+        length = wr->data_length;
+    n = fread(data, 1, length, wr->wav);
+    wr->data_length -= length;
+    return n;
+}
+
+//============== WAV writer functions
+
+struct wavfile_header {
+    char    riff_tag[4];
+    int     riff_length;
+    char    wave_tag[4];
+    char    fmt_tag[4];
+    int     fmt_length;
+    short   audio_format;
+    short   num_channels;
+    int     sample_rate;
+    int     byte_rate;
+    short   block_align;
+    short   bits_per_sample;
+    char    data_tag[4];
+    int     data_length;
+};
+
+WavWriter::WavWriter(const char *filename, int rate)
+{
+    struct wavfile_header header;
+
+    int samples_per_second = rate;
+    int bits_per_sample = 16;
+
+    strncpy(header.riff_tag,"RIFF",4);
+    strncpy(header.wave_tag,"WAVE",4);
+    strncpy(header.fmt_tag,"fmt ",4);
+    strncpy(header.data_tag,"data",4);
+
+    header.riff_length = 0;
+    header.fmt_length = 16;
+    header.audio_format = 1;
+    header.num_channels = 2;
+    header.sample_rate = samples_per_second;
+    header.byte_rate = samples_per_second*(bits_per_sample/8);
+    header.block_align = bits_per_sample/8;
+    header.bits_per_sample = bits_per_sample;
+    header.data_length = 0;
+
+    m_fd = fopen(filename, "w+");
+    if (not m_fd) {
+        throw std::runtime_error("Could not open wav file");
+    }
+
+    fwrite(&header,sizeof(header),1,m_fd);
+
+    fflush(m_fd);
+}
+
+WavWriter::~WavWriter()
+{
+    // The wav file header contains the full file size, we must
+    // write this at the end
+
+    int file_length = ftell(m_fd);
+
+    int data_length = file_length - sizeof(struct wavfile_header);
+    fseek(m_fd,sizeof(struct wavfile_header) - sizeof(int),SEEK_SET);
+    fwrite(&data_length,sizeof(data_length),1,m_fd);
+
+    int riff_length = file_length - 8;
+    fseek(m_fd,4,SEEK_SET);
+    fwrite(&riff_length,sizeof(riff_length),1,m_fd);
+
+    fclose(m_fd);
+}
+
+void WavWriter::write_data(short data[], int length)
+{
+    fwrite(data,sizeof(short),length,m_fd);
+}
+