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