Problem with duration value of HTML5 audio element in iOs

I'm developing a web app for iOs device, but I have a problem with the html5 audio tag... I designed a custom audio player, and I control the song with javascript functions. With safari desktop the app works well, but on safari mobile it doesn't recognize the duration of the audio; the value of the duration property is NaN. I have to play, stop and replay the audio for retrieve the correct value.开发者_Python百科 Probably the cause is that the media preload is disabled on safari mobile... Is there a way to read the correct value at the first shot?

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This is a bug in iOS... even inside the function that gets called on the onloadedmetadata event, you MAY STILL get NaN.

In my case, this happens at random when the user selects a new mp3 and the code dynamically sets the src property. The audio plays fine, yet SOMETIMES, the duration returns NaN, screwing up any progress indicator that depends on that value.

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The medata is available after this event has fired:

 loadedmetadata

More info

https://developer.mozilla.org/en/Introducing_the_Audio_API_Extension