Adjusting the play speed of multimedia files

June 25, 2014

I am trying to adjust the speed of a multimedia file but ATLAS.ti isn’t able to do it for this file, although the same works fine for another file of a similar type. What is going on?

The matter is somewhat complex and perhaps a little confusing:

Your OS–or more precisely, the DirectShow subsystem–selects a decoder for a given multimedia type and hands it over to ATLAS.ti. ATLAS.ti asks the decoder to play back the file at a different rate (faster/slower). If the decoder is unable to do this, the button is disabled.

Now, the same file may be able to play faster or slower on one machine, but not on another. This is because two different types of decoders are used, for example under two different OS versions, or if the user has installed a 3rd party application that has registered itself as a decoder for a given madia type. This is not something that ATLAS.ti (or any application) cannot control this.

So the short answer is: It depends on the decoder (technically, those are called DirectShow filters) that is selected by the OS. As a user, you can experiment with different types of files–some may allow changing the play-rate, others won’t. This does not depend on the specific file type but on the decoder that is selected (but normally the OS chooses certain decoder for certain file types).

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