Re: AAC options dialog 'Encoder Quality'
Re: AAC options dialog 'Encoder Quality'
- Subject: Re: AAC options dialog 'Encoder Quality'
- From: Andrea Barbieri <email@hidden>
- Date: Tue, 24 Apr 2007 20:52:29 +0100 (BST)
Hello Bill,
WS:=William Stewart
WS> The encoder quality property sets internal state in the AAC encoder
WS> to make decisions between faster CPU execution or higher internal
WS> resolution. This is a setting that is applied broadly across all
WS> many CA features - the sample rate converter, the reverb and DLS
WS> Synth AU all support this kind of trade off.
WS>
WS> The internal implementation is left to the particular code involved,
WS> and the gritty details of how the different settings are implemented
WS> may (and do) change over time. For AAC a broad guideline you could
WS> apply is:
WS>
WS> Good
WS> - emphasis on speed of execution, so some operations that may
WS> result in loss of audio precision but are significantly faster
WS> will be taken.
WS> Better
WS> - primarily based on preserving audio precision required for 16
WS> bit sources. There is still some emphasis on faster
WS> operations, but not where it is believe that the faster
WS> operation would compromise typical 16 bit source material
WS> encoding quality
WS> Best
WS> - primarily based on preserving audio precision required for 24 bit
WS> sources.
WS>
WS> HTH
this is really a mine of information!
many, many thanks
andrea
WS>
WS> Bill
WS>
WS> On 22/04/2007, at 5:08 PM, Andrea Barbieri wrote:
WS>
WS> >BF:=Brad Ford
WS> >
WS> > BF> This question could be better answered on the CoreAudio list.
WS> > BF> Forwarding.
WS> > BF>
WS> > BF> -Brad Ford
WS> > BF> QuickTime Engineering
WS> > BF>
WS> > BF> Begin forwarded message:
WS> > BF>
WS> > BF> >From: Andrea Barbieri <email@hidden>
WS> > BF> >Date: April 20, 2007 6:26:59 AM PDT
WS> > BF> >To: email@hidden
WS> > BF> >Subject: AAC options dialog 'Encoder Quality'
WS> > BF> >
WS> > BF> >Hello,
WS> > BF> >
WS> > BF> >when using SoundConverter (I know I should be moving to the newer
WS> > BF> >API!) and
WS> > BF> >launching the options dialog (with title "MPEG-4 Audio Compressor")
WS> > BF> >for the
WS> > BF> >AAC component I wonder what changes when selecting the different
WS> > BF> >option
WS> > BF> >settings for Encoder Quality (Good, Better and Best).
WS> > BF> >
WS> > BF> >many thanks,
WS> > BF> >andrea
WS> > BF>
WS> >
WS> >It is interesting that Technical Q&A QA1437:
WS> >http://developer.apple.com/qa/qa2006/qa1437.html
WS> >
WS> >contains a reference to the Encoder Quality parameter, it is flagged only
WS> >as an expert parameter (not invisible) but it does not show up in the
WS> >StdAudio dialog!
WS> >
WS> >best regards,
WS> >andrea
WS> >--
WS> >Andrea Barbieri
WS> >Moving Image Research http://www.movingimageresearch.com/
WS> >The Workshop, Hampton Lane, Bristol, BS6 6LE, UK
WS> >Tel: +44 117 9732200 FAX: +44 117 9732210
WS> >PGP ID=0x034DFD5A KeyFingerprint=C168EA9A7189538D214F1281A7529F32034DFD5A
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WS>
--
Andrea Barbieri
Moving Image Research http://www.movingimageresearch.com/
The Workshop, Hampton Lane, Bristol, BS6 6LE, UK
Tel: +44 117 9732200 FAX: +44 117 9732210
PGP ID=0x034DFD5A KeyFingerprint=C168EA9A7189538D214F1281A7529F32034DFD5A
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