conformance testing of bitstreams, how to |
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conformance testing of bitstreams, how to |
  Dec 22 2005, 20:40
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#1
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Group: Members Posts: 3 Joined: 22-December 05 Member No.: 26588  |
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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Dec 23 2005, 06:27
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#2
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 Group: Members Posts: 42 Joined: 29-May 04 Member No.: 14392 |
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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 Dec 28 2005, 00:31
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#3
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Group: Members Posts: 3 Joined: 22-December 05 Member No.: 26588 |
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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Dec 28 2005, 06:20
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#4
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Group: Members Posts: 6 Joined: 24-October 05 Member No.: 25321 |
Hi,
 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.  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.  You must have the reference file & the file decoded by using your decoder. 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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Mar 22 2006, 10:10
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#5
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Group: Members Posts: 6 Joined: 16-March 06 Member No.: 28497 |
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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Lo-Fi Version | Time is now: 19th June 2013 - 16:05 |
