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Joined: Apr 2004
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Don't Panic!
Don't Panic!
Joined: Apr 2004
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My work-in-progress /etc/squeezeboxserver/custom-convert.conf:

Quote
flc flc squeezebox <MAC address of your Touch or Transporter>
# FT:{START=--skip=%t}U:{END=--until=%v}
[FLAC] -dc --totally-silent $START$ $END$ -- $FILE$ | [sox] -q --replay-gain album -t WAV - -t FLAC -C0 -b24 - rate -v -M -a -b 90.7 88200 dither -S

flc flc transcode <MAC address of your Touch or Transporter>
# FT:{START=--skip=%t}U:{END=--until=%v}
[flac] -dc --totally-silent $START$ $END$ -- $FILE$ | [sox] -q --replay-gain album -t wav - -t flac -C0 -b24 - rate -v -M -a -b 90.7 88200 dither -S
Still not sure what the transcode entry is for, and I don't think it is strictly necessary for what we want to achieve.

Oh, and my FLAC library currently doesn't have any replay gain tags, so --replay-gain album won't do anything at the moment.


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Knows where his towel is
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[Tongue in Cheek Mode]

Can someone tell me what this thread is about and how it relates to Meridian?

[\Tongue in Cheek Mode]

I've thought recently that the board might usefully be split into Servers and Conventional areas rather than the chronological system.


Malcolm
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Don't Panic!
Don't Panic!
Joined: Apr 2004
Posts: 12,733
Likes: 88
Originally Posted by MalcolmW
[Tongue in Cheek Mode]

Can someone tell me what this thread is about and how it relates to Meridian?

[\Tongue in Cheek Mode]
LOL. We're trying to get our non-Meridian sources resolution enhancing and upsampling prior to connection to our Meridian kit. That way we'll minimize jitter from source to processor. I guess we'll soon be trying to work out how our upsampling compares to Meridian's wink

Last edited by VirusKiller; 2010-09-05 18:58.

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President of the Imperial Galactic Government
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Hi Malcolm, in the absence of any f/w updates (???) it's also a 1/2-chance to put some apodizing style filters in the squeeze centre and on to the processor.

Hi VK,

we'll need to figure out a way of ignoring files that are already 96k as these get bumped down to 88 which isn't a good thing. IIRC one of the posters on the slim forum said he did it but I don't recall seeing the method.


Rgds,
Nick


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Don't Panic!
Don't Panic!
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The output at 16-bits (when you've requested 24-bits) bug is already fixed in SoX 14.3.1 which I've just compiled on my Linux system.

@Nick - I think the easiest (only?) solution is to store anything that isn't 44.1kHz as an uncompressed .WAV.


Roon Developer and ex-moderator of this Forum
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President of the Imperial Galactic Government
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Hmmm....don't like that as you'll lose the tags. There must be a command that says (if >= 96k then ignore, otherwise do the flc -flc thing).

I think I am already at 14.3.1.

cheers


Rgds,
Nick


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Don't Panic!
Don't Panic!
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From michael123 on why he want's to suppress dither:
Originally Posted by michael123
Dithering is usually used in conjunction with noise shaping...(which I clearly see in some CD tracks in Audacity.. blue band / spectrum view around 18-21KHz)

No dithering shall be applied in upsampling from 44.1/16 to 96/24. It was a bug, and the developer already received some "kind words" (I saw the correspondence on the sox mailing list)

Going back from 32bit (internal sox representation) to 24bit will indeed just cut lower 8bit, but that's beyond 144db.. I could not care less.. It is just a noise anyway
Indeed (and unfortunately?), sox 14.3.1 no longer applies dither automatically when going from 16/44.1 to 24/88.2. I think this is a mistake.

From the master:
Originally Posted by Bob/518 manual
It is well established that in order for linearity to be maintained, dither must be applied at every non-trivial processing stage. By non-trivial, we include all operations that modify a sample.

Further, the 518 manual is clear that dither should be applied when increasing the sample word length.


Roon Developer and ex-moderator of this Forum
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Don't Panic!
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I now have some serious doubts on using sox. It refuses to add dither (when manually requested) for the simple operation of increasing word length from 16 to 24 bits. The 518 *does* add dither when it does this and I know what I'd rather trust. Still, as dither can still be applied as part of the upsampling operation, maybe it is ok. I might investigate 3rd party plugins to sox though.

Will try and do some actual listening tomorrow!


Roon Developer and ex-moderator of this Forum
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Don't Panic!
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Oh hang on. Perhaps the application of dither when *increasing* word size is purely for resolution enhancement purposes?

Still, I think it's important to get the sox developers to allow this.


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President of the Imperial Galactic Government
President of the Imperial Galactic Government
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Originally Posted by VirusKiller
Originally Posted by MalcolmW
[Tongue in Cheek Mode]

Can someone tell me what this thread is about and how it relates to Meridian?

[\Tongue in Cheek Mode]
LOL. We're trying to get our non-Meridian sources resolution enhancing and upsampling prior to connection to our Meridian kit. That way we'll minimize jitter from source to processor. I guess we'll soon be trying to work out how our upsampling compares to Meridian's wink

You can't catch Joel out. He can always find an excuse to talk about something which is actually off-topic... wink

Get well soon. (I hope you are taking your whisky: it'll help, it really will.)


Ex-moderator
Sitting room: dCS Network Bridge, 818v3, HD621, 8kSE
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Don't Panic!
Don't Panic!
Joined: Apr 2004
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Likes: 88
And to finish off today's very productive learning mission, if anyone wants to follow the fun, check out this thread from my first post in it:

http://forums.slimdevices.com/showthread.php?p=574502#post574502

I don't claim to be an expert on dither at all, but I think that michael123 is mistaken in his understanding. And, unfortunately, he has implied that he had a hand in sox no longer automatically applying dither during upsampling operations.

@nic - just off for a wee dram now smile


Roon Developer and ex-moderator of this Forum
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President of the Imperial Galactic Government
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Originally Posted by VirusKiller
@nic - just off for a wee dram now smile

That's the spirit.


Ex-moderator
Sitting room: dCS Network Bridge, 818v3, HD621, 8kSE
Library: dCS Rossini Apex DAC/Clock, Clearaudio Innovation, Audio Research PH2, Mjölnir KGST, Mjölnir PureBipolar
Music Room: 210, D33
Kitchen: RPi/RoonBridge, Genelec 6010 actives
Desk: Merging Anubis
Server: Roon/ROCK/NUC

Headphones: Stax SR-X9000, Stax SR-007, Stax SR-404LE, Audeze LCD-X...

Oldest audio file: 1889 Edison cylinder
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