这是一个打开.ogg文件并打印一些基本信息的工作示例。所有包装函数(close
此场景中不需要)都已实现,因此生成的OggVorbis_File
结构是完全可搜索的。
#include <vorbis/vorbisfile.h>
#include <iostream>
#include <cassert>
#include <fstream>
#include <iomanip>
#include <vector>
size_t read(void* buffer, size_t elementSize, size_t elementCount, void* dataSource) {
assert(elementSize == 1);
std::ifstream& stream = *static_cast<std::ifstream*>(dataSource);
stream.read(static_cast<char*>(buffer), elementCount);
const std::streamsize bytesRead = stream.gcount();
stream.clear(); // In case we read past EOF
return static_cast<size_t>(bytesRead);
}
int seek(void* dataSource, ogg_int64_t offset, int origin) {
static const std::vector<std::ios_base::seekdir> seekDirections{
std::ios_base::beg, std::ios_base::cur, std::ios_base::end
};
std::ifstream& stream = *static_cast<std::ifstream*>(dataSource);
stream.seekg(offset, seekDirections.at(origin));
stream.clear(); // In case we seeked to EOF
return 0;
}
long tell(void* dataSource) {
std::ifstream& stream = *static_cast<std::ifstream*>(dataSource);
const auto position = stream.tellg();
assert(position >= 0);
return static_cast<long>(position);
}
int main() {
// Open file stream
std::ifstream stream;
stream.open("C:\\path\\to\\file.ogg", std::ios::binary);
OggVorbis_File file;
const ov_callbacks callbacks{read, seek, nullptr, tell};
int result = ov_open_callbacks(&stream, &file, nullptr, 0, callbacks);
if (result < 0) {
std::cout << "Error opening file: " << result << std::endl;
return 0;
}
// Read file info
vorbis_info* vorbisInfo = ov_info(&file, -1);
std::cout << "File info: " << vorbisInfo->rate << "Hz, "
<< vorbisInfo->channels << " channels" << std::endl;
// Close file
ov_clear(&file);
}
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