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conformance testing of bitstreams, how to
barbeM
post Dec 22 2005, 20:40
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Im learing proper conformance testing of mp3 bitstream playback - can someone go over the process that is used - giving step by step for a newbie?

What tests should be run? How do you verify the results? etc....or where do I find the info out about how to properly do this?

regards

barbe

This post has been edited by barbeM: Dec 22 2005, 20:41
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metaller
post Dec 23 2005, 06:27
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QUOTE (barbeM @ Dec 22 2005, 11:40 PM)
Im learing proper conformance testing of mp3 bitstream playback - can someone go over the process that is used - giving step by step for a newbie?

What tests should be run?  How do you verify the results?  etc....or where do I find the info out about how to properly do this?

regards

barbe
*

Read this: http://www.underbit.com/resources/mpeg/audio/compliance/

Official spec for conformance testing:
ISO/IEC 11172-4:1995
ISO/IEC 13818-4:1998
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barbeM
post Dec 28 2005, 00:31
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Ah thanks - I was already looking at that document and the other refs from ISO -- but what Im really looking for is perhaps some test tools or scripts?

Once I get the raw audio file output from the decoder - what do I do to compare it against the refrence file?

Must I write a script that goes thru and does a difference signal between the two files (original - decoder output) -- then compile that data and do an RMS on the output file? OR is there a tool that is already out there for people to use? Im sure this must have been done by others....but I cant seem to find anything on it.

Also - I have seen refrences to MD5 comparisons used in other testing guides (Phillips) -- is this an alternative way of checking?? I thought MD5 meant bit exact -- so this test mentioned with difference signals implies to me that they will NOT be bit exact....

Sorry Im still a bit confused....(newbie blush)

Barbe


QUOTE (metaller @ Dec 22 2005, 09:27 PM)
QUOTE (barbeM @ Dec 22 2005, 11:40 PM)
Im learing proper conformance testing of mp3 bitstream playback - can someone go over the process that is used - giving step by step for a newbie?

What tests should be run?  How do you verify the results?  etc....or where do I find the info out about how to properly do this?

regards

barbe
*

Read this: http://www.underbit.com/resources/mpeg/audio/compliance/

Official spec for conformance testing:
ISO/IEC 11172-4:1995
ISO/IEC 13818-4:1998
*

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sagar_kempe
post Dec 28 2005, 06:20
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Hi,

sad.gif If you have understood what are the cirteria for the conformance test then it is easier to do the testing. you have to check the RMS diff & Absolute diff. the former one is more important.

smile.gif For calculating the RMS diff, the formula is RMS diff = sqrt(summation(sq(r-t))/n)
where t is i'th sample from decoder under test
& r is i'th sample from reference decoder.

blink.gif You must have the reference file & the file decoded by using your decoder.

cool.gif Then u can write a C program to calculate the RMS diff & Abs diff values.









QUOTE (barbeM @ Dec 28 2005, 05:01 AM)
Ah thanks - I was already looking at that document and the other refs from ISO -- but what Im really looking for is perhaps some test tools or scripts?

Once I get the raw audio file output from the decoder - what do I do to compare it against the refrence file?

Must I write a script that goes thru and does a difference signal between the two files (original - decoder output) -- then compile that data and do an RMS on the output file?  OR is there a tool that is already out there for people to use?  Im sure this must have been done by others....but I cant seem to find anything on it.

Also - I have seen refrences to MD5 comparisons used in other testing guides (Phillips) -- is this an alternative way of checking??  I thought MD5 meant bit exact -- so this test mentioned with difference signals implies to me that they will NOT be bit exact....

Sorry Im still a bit confused....(newbie blush)

Barbe


QUOTE (metaller @ Dec 22 2005, 09:27 PM)
QUOTE (barbeM @ Dec 22 2005, 11:40 PM)
Im learing proper conformance testing of mp3 bitstream playback - can someone go over the process that is used - giving step by step for a newbie?

What tests should be run?  How do you verify the results?  etc....or where do I find the info out about how to properly do this?

regards

barbe
*

Read this: http://www.underbit.com/resources/mpeg/audio/compliance/

Official spec for conformance testing:
ISO/IEC 11172-4:1995
ISO/IEC 13818-4:1998
*


*

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infopjh
post Mar 22 2006, 10:10
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It seems that RMS level only suit for the supplied sine sweep (20Hz-10kHz) with an amplitude of -20dB relative to full scale. for example the test bitstream:compl.mpg,
but other bitstream is not the same, Must we calculate RMS for every bitstream and check whether RMS<2^-15/sqrt(12) ? I still fill confused.
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