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Getting ready to transcode library to AAC
Eli
post Jan 18 2013, 14:59
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I am getting ready to transcode my ~2TB flac library to AAC-LC in an MP4 container and want to be sure I get it right.

My intention is to encode at ~96kbps TVBR with QAAC. The goal is for portability and streaming, and this seems to be a good quality level that will give reasonable listening (I still have the lossless archive).

Is TVBR widely supported? I know many years ago when I used to encode to LAME MP3 VBR ipods had a hard time with it.



I need to pick the right tool for transcoding and have some specific tasks that I want to achieve and can hopefully achieve all of them in one transcode step.

- Scale down album art automatically. Probably to <50kb and 500x500. Is this still to big?
--- 90+% of my albums have embedded and folder.jpg, a minority have one or the other. If they differ, I would like to scale down from the higher resolution one.

- Identify HDCD tracks, and encode to 24b on the fly

- Identify pre-emph files and de-emph

- Apply EBU R128 ReplayGain ( I still need to calculate EBU R128 ReplayGain values for my flac files)

Is there a tool that can do all of these?

This post has been edited by Eli: Jan 18 2013, 15:18


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http://forum.dbpoweramp.com/showthread.php?t=21072
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robertcollier4
post Jan 18 2013, 18:23
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Results of the public AAC listening test @ 96 kbps (July 2011)

Bootstrap Analysis
Nero CVBR TVBR FhG CT low_anchor
3.698 4.391 4.342 4.253 4.039 1.545

ANOVA Analysis
CVBR TVBR FhG CT Nero low_anch
4.39 4.34 4.25 4.04 3.70 1.55

CVBR scores a tiny tiny tiny bit above TVBR - but marginally (4.391 vs 4.342 for Bootstrap and 4.39 vs 4.34 for ANOVA).

In return for that tiny marginally higher score, the 'Bitrate table' shows that the mean bitrate of CVBR was 101 vs 94 for TVBR.

So - CVBR can give you possibly a marginally better quality - but at an average 7% increase in filesize.

Both TVBR and CVBR score tops in quality and significantly better than the rest of the competition - and in my opinion the 7% average filesize improvement overweighs the marginal quality gain given by CVBR over TVBR.

The comparison isn't really fair because equivalent filesizes aren't being compared - and if you are willing to go for the 7% bigger filesize - then you could rather just bump up the TVBR quality setting and probably get a better TVBR quality vs CVBR quality at the same filesize.

This post has been edited by robertcollier4: Jan 18 2013, 18:36
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IgorC
post Jan 19 2013, 00:34
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QUOTE (robertcollier4 @ Jan 18 2013, 14:23) *
The comparison isn't really fair because equivalent filesizes aren't being compared - and if you are willing to go for the 7% bigger filesize - then you could rather just bump up the TVBR quality setting and probably get a better TVBR quality vs CVBR quality at the same filesize.

You're right.
Just one clarification. There was no way to match the bitrates between TVBR and CVBR.
TVBR can produce ~94 kbps or ~107-110 kbps but not ~100-101 kbps as CVBR 96 kbps. People had interest to test TVBR vs CVBR so we have decided to include the most close bitrate settings for both. Also testing TVBR at ~107 kbps to strongest competitor Fraunhofer AAC (new Winamp 5.62, VBR 3) ~100 kbps wouldn't be fair.

P.S. Even if both VBR modes would be at ~100 kbps still their scores will be practically the same. This personal test confirms it.

This post has been edited by IgorC: Jan 19 2013, 01:06
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