AAC Characteristic of single tone

hb chen

Dear Experts,

My environment: DM8168/SDK Version: VCSDK(based on DVRRDK 2.8).

I have a question about AAC encoder.
I encode single tone audio by DSP AAC encorder.

Input: 19KHz single tone, 16bit.
48KHz sampleing rate.
Output: 128kbps AAC.

Spectrum of encoded AAC as below figure:

There are many response at different frequency that lower than 15KHz.
Is it normal? Why should not be 19KHz only?

over 9 years ago

0 Margarita Gashova over 9 years ago

TI__Guru* 80190 points

Hello,

For VCSDK contact your local FAE or you could search in the e2e for similar issue.
You could check the aac encoder user guide.

You could check this thread also:

https://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/481215

BR
Margarita

0 hb chen over 9 years ago in reply to Margarita Gashova

Expert 2640 points

Dear Margarita,

e2e.ti.com/.../481215
This link is my post before.

But question here is different.
Cut off frequency of 128kbps AAC is 15KHz,
there should be no response when I encode 19KHz single tone audio to aac.
I don't know whether it is AAC characteristic or encoder bug.

HB.

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AAC Characteristic of single tone