[MLA] Lossy encoder clipping

[Bob Katz]

Ian, it's been a while since I performed this test. I would have to 
retest to be sure, but to the best of my recollection, *the clipping is 
ONLY on the repro side and only when converted to fixed point.* Remember 
that all the codecs (both encode and decode side) are 32 bit floating 
point.

If you run an attenuator in the floating point domain after the decoder, 
you can fix any over issues which would manifest as clipping when 
converted to fixed. Test it yourself. Run Apple's AU lab with the round 
trip codec and Bitter placed in critical places.

Then put a 24 bit dithering plugin and run a distortion test on a sine 
wave to make sure it's not an illusion. If you guys don't perform this 
test before the weekend, I'll try to do it myself again.


Best wishes,


Bob


On 10/7/18 7:39 PM, Ian Shepherd wrote:
> Hi All !
>
> My recent blog post about lossy encode clipping has had quiet a bit of attention:
>
> http://productionadvice.co.uk/spotify-upload-true-peak/
>
> Including an email from Robert Bleidt @ Fraunhofer. He’s asking if I have specific examples of encodes that have “baked in” the clipping, because his position is that it shouldn’t happen, these days.
>
> I’d like to give him a helpful reply and I’ve experienced problems myself in the past with encoding from Logic and Audacity, for example, but the truth is I don’t have a collection of examples on hand to offer him.
>
> Do any of you have recent examples that I can point him at, or know for sure of current encoders that consistently have issues with extremely loud content ?
>
> Thanks for any suggestions,
>
> Ian
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-- 

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DIGITAL DOMAIN MASTERING STUDIO Author: *Mastering Audio *Digital Domain 
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