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Topic: How to evaluate a fixed-point system? (Read 4440 times) previous topic - next topic
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How to evaluate a fixed-point system?

Hi,
I'm composing a fixed-point DSP code for MPEG Layer2(MP2) now.
The way I evaluate the performance of fixed-point DSP code is to calculated the SNR, which S(signal) represents floating-point ouput and N(noise) respresnts the difference between floating-point and fixed-point.

However, it is found that even the SNR seems not so high but it sounds pretty better while doing listening tests.

Could anyone please tell me a typical SNR which can be as an evaluation heshold?

Regards

How to evaluate a fixed-point system?

Reply #1 –
Quote
Hi,
I'm composing a fixed-point DSP code for MPEG Layer2(MP2) now.
The way I evaluate the performance of fixed-point DSP code is to calculated the SNR, which S(signal) represents floating-point ouput and N(noise) respresnts the difference between floating-point and fixed-point.

However, it is found that even the SNR seems not so high but it sounds pretty better while doing listening tests.

Could anyone please tell me a typical SNR which can be as an evaluation heshold?

Regards
[a href="index.php?act=findpost&pid=309387"][{POST_SNAPBACK}][/a]


SNR is given as 6.01*n + 0.01 db
where n is the step size
normally you use 16 bit samples
so according to the formula 6*16 = 96 db for CD quality music
But as far as i know if the SNR crosses 70db then it passes the conformance testing of MPEG.so SNR > 70db should be ok.

How to evaluate a fixed-point system?

Reply #2 –
Thank you so much!! 
Quote
Quote
Hi,
I'm composing a fixed-point DSP code for MPEG Layer2(MP2) now.
The way I evaluate the performance of fixed-point DSP code is to calculated the SNR, which S(signal) represents floating-point ouput and N(noise) respresnts the difference between floating-point and fixed-point.

However, it is found that even the SNR seems not so high but it sounds pretty better while doing listening tests.

Could anyone please tell me a typical SNR which can be as an evaluation heshold?

Regards
[a href="index.php?act=findpost&pid=309387"][{POST_SNAPBACK}][/a]


SNR is given as 6.01*n + 0.01 db
where n is the step size
normally you use 16 bit samples
so according to the formula 6*16 = 96 db for CD quality music
But as far as i know if the SNR crosses 70db then it passes the conformance testing of MPEG.so SNR > 70db should be ok.
[a href="index.php?act=findpost&pid=311332"][{POST_SNAPBACK}][/a]

How to evaluate a fixed-point system?

Reply #4 –
Quote
http://www.underbit.com/resources/mpeg/audio/compliance/
[a href="index.php?act=findpost&pid=311586"][{POST_SNAPBACK}][/a]

Thanks! Garf....
I tried to do compliance test according to the instructions on website.
However, the test files, test file and reference file, are not binary ones.
Could you tell me where to get the binary version of test files?
 

How to evaluate a fixed-point system?

Reply #5 –
Quote
Quote
http://www.underbit.com/resources/mpeg/audio/compliance/
[a href="index.php?act=findpost&pid=311586"][{POST_SNAPBACK}][/a]

Thanks! Garf....
I tried to do compliance test according to the instructions on website.
However, the test files, test file and reference file, are not binary ones.
Could you tell me where to get the binary version of test files?
[a href="index.php?act=findpost&pid=311771"][{POST_SNAPBACK}][/a]


Reading the documentation would be a good start.