Initial public release of the 2024A software.

managed_components/chmorgan__esp-audio-player/audio_wav.cpp

@@ -0,0 +1,81 @@
+#include <string.h>
+#include <stdio.h>
+#include "audio_wav.h"
+
+static const char *TAG = "wav";
+
+/**
+ * @param fp
+ * @param pInstance - Values can be considered valid if true is returned
+ * @return true if file is a wav file
+ */
+bool is_wav(FILE *fp, wav_instance *pInstance) {
+    fseek(fp, 0, SEEK_SET);
+
+    size_t bytes_read = fread(&pInstance->header, 1, sizeof(wav_header_t), fp);
+    if(bytes_read != sizeof(wav_header_t)) {
+        return false;
+    }
+
+    wav_header_t *wav_head = &pInstance->header;
+    if((NULL == strstr(reinterpret_cast<char *>(wav_head->ChunkID), "RIFF")) ||
+        (NULL == strstr(reinterpret_cast<char*>(wav_head->Format), "WAVE"))
+      )
+    {
+        return false;
+    }
+
+    // decode chunks until we find the 'data' one
+    wav_subchunk_header_t subchunk;
+    while(true) {
+        bytes_read = fread(&subchunk, 1, sizeof(wav_subchunk_header_t), fp);
+        if(bytes_read != sizeof(wav_subchunk_header_t)) {
+            return false;
+        }
+
+        if(memcmp(subchunk.SubchunkID, "data", 4) == 0)
+        {
+            break;
+        } else {
+            // advance beyond this subchunk, it could be a 'LIST' chunk with file info or some other unhandled subchunk
+            fseek(fp, subchunk.SubchunkSize, SEEK_CUR);
+        }
+    }
+
+    LOGI_2("sample_rate=%d, channels=%d, bps=%d",
+            wav_head->SampleRate,
+            wav_head->NumChannels,
+            wav_head->BitsPerSample);
+
+    return true;
+}
+
+/**
+ * @return true if data remains, false on error or end of file
+ */
+DECODE_STATUS decode_wav(FILE *fp, decode_data *pData, wav_instance *pInstance) {
+    // read an even multiple of frames that can fit into output_samples buffer, otherwise
+    // we would have to manage what happens with partial frames in the output buffer
+    size_t bytes_per_frame = (pInstance->header.BitsPerSample / BITS_PER_BYTE) * pInstance->header.NumChannels;
+    size_t frames_to_read = pData->samples_capacity / bytes_per_frame;
+    size_t bytes_to_read = frames_to_read * bytes_per_frame;
+
+    size_t bytes_read = fread(pData->samples, 1, bytes_to_read, fp);
+
+    pData->fmt.channels = pInstance->header.NumChannels;
+    pData->fmt.bits_per_sample = pInstance->header.BitsPerSample;
+    pData->fmt.sample_rate = pInstance->header.SampleRate;
+
+    if(bytes_read != 0)
+    {
+        pData->frame_count = (bytes_read / (pInstance->header.BitsPerSample / BITS_PER_BYTE)) / pInstance->header.NumChannels;
+    } else {
+        pData->frame_count = 0;
+    }
+
+    LOGI_2("bytes_per_frame %d, bytes_to_read %d, bytes_read %d, frame_count %d",
+            bytes_per_frame, bytes_to_read, bytes_read,
+            pData->frame_count);
+
+    return (bytes_read == 0) ? DECODE_STATUS_DONE : DECODE_STATUS_CONTINUE;
+}