[Mp4-tech] [HE-AAC]understanding of AAC+ conformance test

[Andy Quan]

Hey Andreas,
The explanation is crystal clear. Thank you.
And here comes another question. As I remember, some early discussion
of LC decoder in this forum says that there is no way for a 16-bit
output PCM to pass RMS conformance test in LC suite as the reference
is an independent 24-bit sound file. If this is true, how can we judge
the compliance of this kind of LC decoder? As we all know, most LC
decoders available today provide 16-bit output rather than 24-bit
ones.
On 4/8/08, Schneider, Andreas <andreas.schneider dolby.com> wrote:
> Hi Andy,
>
> If you want to call your decoder ISO compliant, it must produce an output signal that satisfies the criteria for max. diff and RMS as defined by ISO. The conformance document actually tells you to apply these thresholds in the column "test procedure" of the table that defines the conformance bitstreams.
> So any decoder that claims that it is fully ISO compliant effectively claims that it passes all these conformance tests.
>
> Andreas
>
> Andreas Schneider
> Senior Research Engineer
>
> Dolby Germany GmbH
> Deutschherrnstr. 15 - 19
> 90429 Nuernberg, Germany
> http://www.dolby.com
>
> + 49 911 928 91 - 26 (phone)
> + 49 911 928 91 - 99 (fax)
> mailto:Andreas.Schneider dolby.com
>
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>
> > -----Original Message-----
> > From: mp4-tech-bounces lists.mpegif.org
> > [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Andy Quan
> > Sent: Dienstag, 8. April 2008 15:36
> > To: mp4-tech lists.mpegif.org
> > Subject: [Mp4-tech] [HE-AAC]understanding of AAC+ conformance test
> >
> > I am recently working on AAC+ ISO conformance test(SBR,
> > 14496-4) for a fixed point decoder. One thing that keeps
> > puzzling me is what the significance of passing conformance test is.
> >
> > As the whole suite of conformance test compasses many
> > different test streams with different accuracy criteria of
> > both MaxDiff and RMS threshold, failure in any of them leads
> > to being "not passed" in this "conformance test". However
> > some of these test cases are not meant for syntax checking
> > but for computational accuracy. As we all know, fixed point
> > decoder prioritizes performance and usually puts
> > computational accuracy a little behind.
> >
> > In such cases, i mean if it can not pass all CT tests, can we
> > still OFFICIALLY call it "ISO compliant decoder"? (I would
> > rather take "compliant" as "compliant syntax parsing") I find
> > a lot of commercial and embedded dedicated AAC+ codecs claim
> > themselves "fully compliant to ISO". Does this mean that they
> > can pass this ISO conformance test suite?
> >
> > Any one got comment? Thanks in advance.
> >
> > --
> > Regards,
> > Andy Quan
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-- 
Regards,
Andy Quan