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Blankdj
2009-09-06, 13:17
I'm using XP operating system and iTunes library - files are Apple Lossless. My SB3 runs firmware 127 and Squeezecentre is 7.3.3. Using SB3 digital out to external DAC. No lame installed and assuming default bitrate in Squeezecentre of no limit.

The following display is found on the player and Squeezecentre page for files as they play - but only for files from iTunes library:

eg - Bitrate: 817kbps VBR (Converted to 705.6kbps ABR)

I appreciate that Squeezecentre is converting Apple Lossless into FLAC so SB3 can read, but this does not happen when playing FLAC files from other locations.

Any thoughts on why this might be happening and how to stop the conversion?

funkstar
2009-09-06, 14:20
I appreciate that Squeezecentre is converting Apple Lossless into FLAC so SB3 can read, but this does not happen when playing FLAC files from other locations.

Any thoughts on why this might be happening and how to stop the conversion?
I don't really understand what you are asking here. Your ALAC files need to be transcoded to work on the SB3, FLAC files in another location do not need to be transcoded as they are already in a format the SB3 can play natively.

Without conversion, the ALAC files cannot be played.

Blankdj
2009-09-06, 15:05
I was hoping that converting Apple Lossless to FLAC wouldn't impose a fixed bitrate - and the quality degradation that might result. But perhaps I don't understand what ABR is.

snarlydwarf
2009-09-06, 15:10
I was hoping that converting Apple Lossless to FLAC wouldn't impose a fixed bitrate - and the quality degradation that might result. But perhaps I don't understand what ABR is.

VBR = variable bit rate
ABR = average bit rate

ABR -could- be "convert this stream, trying to keep it at this target bit rate"

Or, in this case, it is "the stream is X bits long, and lasts Y seconds, so the average bit rate is X/Y".

Blankdj
2009-09-06, 15:13
Yes, thanks for that. What puzzles me is that the file is always converted to 705.6 ABR, no matter what the file VBR bitrate. So Squeezecentre appears to favour a fixed average bitrate, which then leads to my thinking some files may be compromised in the process.

Is there any contemplation of players processing Apple Lossless natively?

Again, all comments appreicated as I'm new to all this.

Ben Sandee
2009-09-06, 15:45
On Sun, Sep 6, 2009 at 5:13 PM,
Blankdj<Blankdj.3y445c1252275242 (AT) no-mx (DOT) forums.slimdevices.com> wrote:
>
> Yes, thanks for that. What puzzles me is that the file is always
> converted to 705.6 ABR, no matter what the file VBR bitrate. So
> Squeezecentre appears to favour a fixed average bitrate, which then
> leads to my thinking some files may be compromised in the process.

That bitrate is a FLAC bitrate which means there is no loss
whatsoever. Your audio is coverted from ALAC to FLAC and your audio
is perfectly relayed to your audio equipment.

Ben

seanadams
2009-09-06, 15:47
Yes, thanks for that. What puzzles me is that the file is always converted to 705.6 ABR, no matter what the file VBR bitrate. So Squeezecentre appears to favour a fixed average bitrate, which then leads to my thinking some files may be compromised in the process.

Is there any contemplation of players processing Apple Lossless natively?

Again, all comments appreicated as I'm new to all this.

It doesn't actually know the bit rate in advance. 705.6 is just an estimate assuming 50% compression of 44.1/16 material.

50% (44.1 * 16 * 2) = 705.6.

The actual FLAC bit rate is likely to be pretty close to the ALAC rate, but the important thing to realize is that no matter what the resultant bit rate IT WILL BE LOSSLESS. Some compressors are better than others, and even the same compressor can yield different bit rates by varying parameters which tell it how hard to try. When discussing lossless codecs the bitrate is no indication whatsoever of sound quality.

snarlydwarf
2009-09-06, 15:48
Yes, thanks for that. What puzzles me is that the file is always converted to 705.6 ABR, no matter what the file VBR bitrate. So Squeezecentre appears to favour a fixed average bitrate, which then leads to my thinking some files may be compromised in the process.

Because SC does not recode the whole file before sending it (therefore it has no idea exactly how many bits it is as FLAC until it is done sending it)...

The actual number is fudged.



Is there any contemplation of players processing Apple Lossless natively?

Again, all comments appreicated as I'm new to all this.

You're not losing any data.

That's the whole point of lossless.

Blankdj
2009-09-06, 18:17
Good news if the ABR number is a placeholder.

I'm interested in native processing of Apple Lossless because of ffwd functions and others that come with native processing.

Thanks for your help.

And extra thanks to Sean for the product line!

funkstar
2009-09-07, 06:51
Is there any contemplation of players processing Apple Lossless natively?

Again, all comments appreicated as I'm new to all this.
ALAC playback will not and indeed cannot be added to the IP3K range of players (SB2, Receiver, Transporter and Boom). AAC will be supported natively on Touch and Radio, I can't remember if that also includes ALAC though.

andyg
2009-09-07, 07:56
We want to include native ALAC too.

And as for seeking support in AAC/ALAC, I have spent a ton of time trying to get this to work and it still seems a long way off. So, seeking may not be there when we ship. :(