如果该音调采用的是ASDR包络，请写一个matlab函数测出他的asdr参数

ASDR（Attack-Sustain-Decay-Release）是一种常见的包络形状参数，用于描述音频信号的起始、持续和结束阶段。以下是一个示例MATLAB函数，用于测量给定音频信号的ASDR参数：

function [attack, sustain, decay, release] = analyze_asdr(signal, fs)
    % 预设参数
    threshold = 0.01; % 衰减阈值，用来确定开始和结束阶段

    % 计算音频信号的幅度
    amplitude = abs(signal);
    
    % 分析 Attack 阶段
    [~, attack_index] = max(amplitude);
    attack_time = attack_index / fs;
    
    % 分析 Sustain 阶段
    sustain_start_index = attack_index;
    while amplitude(sustain_start_index) >= threshold
        sustain_start_index = sustain_start_index + 1;
    end
    sustain_time = (sustain_start_index - attack_index) / fs;
    
    % 分析 Decay 阶段
    decay_start_index = sustain_start_index;
    while amplitude(decay_start_index) >= threshold
        decay_start_index = decay_start_index + 1;
    end
    decay_time = (decay_start_index - sustain_start_index) / fs;
    
    % 分析 Release 阶段
    release_start_index = decay_start_index;
    while amplitude(release_start_index) >= threshold
        release_start_index = release_start_index + 1;
    end
    release_time = (release_start_index - decay_start_index) / fs;
    
    % 返回ASDR参数
    attack = attack_time;
    sustain = sustain_time;
    decay = decay_time;
    release = release_time;
end

在这个示例中，函数`analyze_asdr`接受两个参数：音频信号`signal`和采样率`fs`。首先，它计算音频信号的幅度。然后，根据给定的阈值，分析音频信号的Attack、Sustain、Decay和Release阶段的持续时间。

您可以调用这个函数来测量您的音频信号的ASDR参数。例如：

% 读取音频文件
[y, fs] = audioread('your_audio_file.wav');

% 测量ASDR参数
[attack, sustain, decay, release] = analyze_asdr(y, fs);

% 输出ASDR参数
disp(['Attack: ', num2str(attack), ' s']);
disp(['Sustain: ', num2str(sustain), ' s']);
disp(['Decay: ', num2str(decay), ' s']);
disp(['Release: ', num2str(release), ' s']);

请将`your_audio_file.wav`替换为您的音频文件路径。

希望这个示例能满足您的需求！如果有任何问题，请随时提问。