Checking if wave file is playing

Posted on 1999-12-28
Medium Priority
Last Modified: 2013-12-03
I use waveOutWrite() to play segments of a large wave file in Visual C++.  After I start playing it, I need to know whether the wave segment finished playing or not.
What is a way to check this?

Question by:mroslyak

Expert Comment

ID: 2309713
waveOutGetPosition( ) ??

Author Comment

ID: 2309847
I tried using waveOutGetPosition() but was not able to get it to work, since I could not find a lot of documentaion on it
A simple example would be nice.

Expert Comment

ID: 2310160
Have you tried looking for the MM_WOM_DONE message? This is how I determine when a segment is complete and when to move to the bext one. Here is an explanation of it:

The MM_WOM_DONE message is sent to a window when the given output buffer is being returned to the application. Buffers are returned to the application when they have been played, or as the result of a call to the waveOutReset function.

wParam = (WPARAM) hOutputDev
lParam = (LONG) lpwvhdr
Handle of the waveform-audio output device that played the buffer.

Address of a WAVEHDR structure identifying the buffer.
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LVL 23

Expert Comment

ID: 2310327
WDB is right. You may find the following article useful.

Recording and Playing Waveform Audio

Expert Comment

ID: 2310807
When u open the device with waveOutOpen , put the CALLBACK_WINDOW flag and a handle to a window . When writing to the device finishes , your window receives a message MM_WOM_DONE .

Accepted Solution

byang earned 200 total points
ID: 2311863
After a successful call to:

   waveOutWrite(..., ph, ...);

just check ph->dwFlags. When the wave buffer is finished playing, WHDR_DONE will be set in dwFlags. So:

   if (WHDR_DONE ==
   { //finished playing

   } else
   { //not finished playing

You are supposed to keep *ph around so you can call waveOutUnprepareHeader() later.

Expert Comment

ID: 2312101
Checking the ph->dwFLags is not as convienent as waiting for the MM_WOM_DONE message. When you check the ph->dwFlags and WHDR_DONE isn't set then you need to keep checking until it is. Therefore, this method will require some extra logic, not to mention it won't be as efficient as processing MM_WOM_DONE.

Expert Comment

ID: 2313378
You don't have to check it in an endless loop, just once in a while. If at any given time you want to check if a wave block finished playing, I'd say WHDR_DONE is the way to go, even if you have a window callback for other purposes already.

If you wait for MM_WOM_DONE, where are you going to put the finished flags for wave blocks ? Some extra variables? You might as well just check dwFlags as the systems sets it for you.

Expert Comment

ID: 2313441
Why would I need to put the finished flags anywhere?? I still have ph and the flags still get set but I won't need to do any extra work in determining when they get set.
   I've worked with many MM apps and  MM_WOM_DONE is always used. I can think of some special instances where it would be useful to keep tabs on the flag, but just to find out when a block has finished, MM_WOM_DONE is the way to go.

Expert Comment

ID: 2314635
Sorry, I have to disagree there. What I mean is, for example, 1 second after a wave started playing, you need to check if it's finished. Using MM_WOM_DONE, how would you do it ? At minimum you need a one-bit flag to indicate if MM_WOM_DONE is sent already. So why not just check dwFlags in wave header, which you already have anyway.

Besides, checking the WHR_DONE is simpler as it doesn't require you to worry about windows message callback.


Expert Comment

ID: 2314720
Maybe I'm missing something here? The only way that method makes sense to me is if you are planning on doing something different to the buffer if it hasn't finished playing after 1 second, other then allowing it to continue to play.    
 Otherwise, why would you want to poll for this when the windows message callback will tell you when it's done? To me this seems very efficent and straight forward.
   Also, when polling the flag, you will have to have your timing just right, otherwise your application could take a performance hit or even experience audio dropouts when playing wave files. So, additional coding would be neccessary to make sure the timing is right.
   And, what is wrong with a windows message callback? They are very easy to setup, efficient to use, not to mention they lend themselves very well to most MM components.
  So, my point is, an application that plays a wave file and uses MM_WOM_DONE to determine and set the "buffer flow" will be more efficient and easier to code then an application that attempts to poll the wave header flags. I've yet to see it done any other way.

Take Care :)

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