problem with solving overlapping sounds

Question

Gino 2014-12-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/167127-problem-with-solving-overlapping-sounds

回答： Geoff Hayes 2014-12-18

I'm currently trying to give my matlab game sound. To stop the sounds from overlapping I found a solution and changed the data accordingly.

SOUND_FILE_NAMES = {'.\sounds\pacman_beginning.wav', '.\sounds\pacman_chomp.wav', ...
                    '.\sounds\pacman_death.wav', '.\sounds\pacman_eatfruit.wav', ...
                    '.\sounds\pacman_eatghost.wav', '.\sounds\pacman_extrapac.wav', ...
                    '.\sounds\pacman_intermission.wav', '.\sounds\pacman_moving.wav'};
SOUND_KEYS = {'Beginning', 'chomp', 'death', 'eatfruit', 'eatghost', ...
                      'extrapac', 'intermission', 'moving'};
SOUND_SAMPLES = [5,5,5,3,3,2,6,5];
obj.audioPlayers = struct();
        for i = 1 : length( SOUND_FILE_NAMES )
            [y, Fs] = audioread(SOUND_FILE_NAMES{i});
            str = 'audioplayer(y,Fs)';
            for j = 2 : SOUND_SAMPLES(i);
                str = sprintf('%s, audioplayer(y,Fs)', str );
            end
            eval( sprintf('obj.audioPlayers.(SOUND_KEYS{i}) = {%s};', str ));
          end
PlaySound(obj,'Beginning');

and the function

function PlaySound( obj, soundName )
          done = false;
          i = 1;
          while ~done && i < length(obj.(soundName))
              if ~obj.(soundName){i}.isplaying()
                  obj.(soundName){i}.play();
                  done = true;
              end
              i = i + 1;
          end
  end

But I only get the error

Reference to non-existent field 'Beginning' 
Error in PlaySound (line 7)
          while ~done && i < length(obj.(soundName))

I don't know how to solve this problem.

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Answer 1

Gino 2014-12-18

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链接

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https://ww2.mathworks.cn/matlabcentral/answers/167127-problem-with-solving-overlapping-sounds#answer_162768

在 MATLAB Online 中打开

Found the problem :

obj.(soundName)

should be

obj.audioPlayers.(soundName)

since that's where everything was saved in the script.

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Answer 2

Geoff Hayes 2014-12-18

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/167127-problem-with-solving-overlapping-sounds#answer_162771

在 MATLAB Online 中打开

Gino - the error message is telling you that there is no field named Beginning in your structure obj which you try to access as *obj.('Beginning').

Note how you are creating the fields in your object:

eval( sprintf('obj.audioPlayers.(SOUND_KEYS{i}) = {%s};', str ));

so the field can most likely be found at

obj.audioplayers.('Beginning')

So using the above code instead will probably help, but I'm not all that clear on what you have intended to do with this object. In the code that initializes the structure,

 for i = 1 : length( SOUND_FILE_NAMES )
     [y, Fs] = audioread(SOUND_FILE_NAMES{i});
     str = 'audioplayer(y,Fs)';
     for j = 2 : SOUND_SAMPLES(i);
          str = sprintf('%s, audioplayer(y,Fs)', str );
     end
     eval( sprintf('obj.audioPlayers.(SOUND_KEYS{i}) = {%s};', str ));
 end

the inner for loop builds the string str but never makes use of the indexing variable j and so the same data is appended to the string in some sort of comma separated list. What is the intent behind this variable?

Also, try avoid using the eval as it makes debugging challenging. Think of an alternate for this line.