PDA

View Full Version : Is Apple Lossless being encoded to AIFF?



Eric Brandon
2004-05-02, 17:26
Today I updated to iTunes 4.5 and Slimserver 5.1.6 in order to archive &
stream in Apple Lossless format.

I set "file formats" in the Slimserver to convert ALC to uncompressed
AIFF (and not to MP3).

The problem is that when I check the bit rate in "now playing" on the
player, it says 128 CBR and shows a song length that's much too long.

How can I tell is ALC is being streamed as uncompressed AIFF, or
compressed to 128 CBR?

Windows XP
iTunes 4.5
Slimserver 5.1.6
Squeezebox firmware v10
Wired Ethernet
External DAC output (coax)

- Eric

kdf
2004-05-02, 23:00
Quoting Eric Brandon <ebran2 (AT) pacbell (DOT) net>:

>
> Today I updated to iTunes 4.5 and Slimserver 5.1.6 in order to archive &
> stream in Apple Lossless format.
>
> I set "file formats" in the Slimserver to convert ALC to uncompressed
> AIFF (and not to MP3).
>
> The problem is that when I check the bit rate in "now playing" on the
> player, it says 128 CBR and shows a song length that's much too long.
>
> How can I tell is ALC is being streamed as uncompressed AIFF, or
> compressed to 128 CBR?

As apple is not very forthcoming regarding details of their audio formats, its
largely reverse engineered. The module that handles ALC is the same one that
handles AAC, which was reverse engineered for AAC, with no foreknowlege of ALC.
Bitrate is hardcoded so that the server can at least play the file. It is not
information that is extracted from the file. If someone knows how to get that,
feel free to post it here :)

The best way to tell now, is look at your processes. If LAME is running, then
its being converted to mp3. If only movdec is running, then its being
uncompressed to AIFF as requested. You can also turn on the d_source debugging
flag in the server settings, and the log will tell you what command is being
used to play the file.
-kdf