# Extremely low audio quality when changing audio playback speed with lowlevel API.

**URL:** <https://qa.fmod.com/t/extremely-low-audio-quality-when-changing-audio-playback-speed-with-lowlevel-api/12245>\
**Category:** FMOD Engine\
**Created:** [January 15, 2016, 5:28am UTC](https://qa.fmod.com/t/extremely-low-audio-quality-when-changing-audio-playback-speed-with-lowlevel-api/12245 "2016-01-15T05:28:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![woc2006](https://avatars.discourse-cdn.com/v4/letter/w/839c29/32.png) [@woc2006](https://qa.fmod.com/u/woc2006)\
**Post date:** [January 15, 2016, 5:28am UTC](https://qa.fmod.com/t/extremely-low-audio-quality-when-changing-audio-playback-speed-with-lowlevel-api/12245/1 "2016-01-15T05:28:34Z")

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In my case, I create ChannelGroup and add channels into it. I change the group playback rete using the following code:

```
FMOD::DSP* dsp; 
float speed = 1.5f;
system->createDSPByType(FMOD_DSP_TYPE_PITCHSHIFT, &dsp);
dsp->setParameterFloat(FMOD_DSP_PITCHSHIFT_PITCH, 1/speed);
group->addDSP(0, dsp);
group->setPitch(speed);

```

the result is the audio group plays 1.5x faster as expected, but sound like highly compressed mp3 with low byterate. My original audio file is 320kbps mp3.

---

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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:** [January 18, 2016, 9:56pm UTC](https://qa.fmod.com/t/extremely-low-audio-quality-when-changing-audio-playback-speed-with-lowlevel-api/12245/2 "2016-01-18T21:56:00Z")

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Hi ,  
The pitch shift effect is not suited to high amounts of shift, so by default about 0.8 to 1.2 is recommended, but if you want to try and increase quality use FMOD\_DSP\_PITCHSHIFT\_FFTSIZE to adjust the quality.