av_guess_format获取avi文件类型失败

Seele

std::string detectVideoType(const std::string& filename) {
    AVFormatContext* formatContext = nullptr;
    const AVOutputFormat* outputFormat = nullptr;

    // Open input file and get format context
    int ret = avformat_open_input(&formatContext, filename.c_str(), nullptr, nullptr);
    if (ret < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Cannot open input file\n");
        return "Unknown";
    }

    // Retrieve stream information
    ret = avformat_find_stream_info(formatContext, nullptr);
    if (ret < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Cannot find stream information\n");
        avformat_close_input(&formatContext);
        return "Unknown";
    }

    // Guess format based on filename
    outputFormat = av_guess_format(nullptr, filename.c_str(), nullptr);
    if (!outputFormat) {
        av_log(nullptr, AV_LOG_ERROR, "Cannot guess file format\n");
        avformat_close_input(&formatContext);
        return "Unknown";
    }

    avformat_close_input(&formatContext);

    // Return format name
    return outputFormat->name;
}

Seele

求助大佬看下！在使用av_guess_forma获取avi文件的类型失败，但是获取mp4是正常的，请问是什么原因呢？