# Apply DSP efx to an "external" signal

**URL:** <https://qa.fmod.com/t/apply-dsp-efx-to-an-external-signal/12379>\
**Category:** FMOD Engine\
**Created:** [March 14, 2016, 1:30pm UTC](https://qa.fmod.com/t/apply-dsp-efx-to-an-external-signal/12379 "2016-03-14T13:30:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![juancito](https://avatars.discourse-cdn.com/v4/letter/j/34f0e0/32.png) [@juancito](https://qa.fmod.com/u/juancito)\
**Post date:** [March 14, 2016, 1:30pm UTC](https://qa.fmod.com/t/apply-dsp-efx-to-an-external-signal/12379/1 "2016-03-14T13:30:38Z")

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Hello,  
Does FMOD allow DSP processing of a signal which is not managed by FMOD channels?  
E.g. Buffer -\> FMOD Processing -\> Buffer

I want to apply some DSP effects on it such as filtering without dealing with channels as I don’t need to play the buffer, I just need the processed bytes.

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**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\
**Post date:** [March 27, 2016, 11:35am UTC](https://qa.fmod.com/t/apply-dsp-efx-to-an-external-signal/12379/2 "2016-03-27T11:35:54Z")

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Hi Juan,  
Apologies for the delay in replying. You can definitely just process data, if you use a channelgroup you can use ChannelGroup::addDSP and if you have some data you want to feed into FMOD you can create your own DSP and use a read callback to pass in a buffer too.

[http://www.fmod.org/documentation/#content/generated/overview/dsptutorial.html](http://www.fmod.org/documentation/#content/generated/overview/dsptutorial.html) can give you some more information.

regards,