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View Full Version : Which format puts heaviest demand on SB?



joek
2006-02-06, 13:09
I want to be able to stress test and am curious as to which of the audio formats would provide a heavy load on the SB3?

Would it be FLAC, since the SB3 would have to uncompress a large audio stream before playing?

Thanks!

pfarrell
2006-02-06, 13:27
joek wrote:
> I want to be able to stress test and am curious as to which of the audio
> formats would provide a heavy load on the SB3?
> Would it be FLAC, since the SB3 would have to uncompress a large audio
> stream before playing?


What do you mean by stress? The CPU runs all the time.
If it is doing more useful work, say uncompressing a FLAC stream,
do you consider that stress? the cycles were going to happen
anyway, electrons would move, etc.

FLAC was designed to be easy to uncompress by very low
capabilities systems. Feeding a stream of bytes
to a D-to-A convertor makes the DA do something, but
that is what it was designed to do.

The SlimServer is much more likely to get stressed,
and only when driving lots of SBs in parallel.
I'm not sure what stress is to a dumb box like
a SqueezeBox. Its a slim device, after all.

--
Pat
http://www.pfarrell.com/music/slimserver/slimsoftware.html

Mark Lanctot
2006-02-06, 13:55
Pat answered most of your other questions, but I
guess you should qualify: load on the system in
terms of bandwidth required or load on the
Squeezebox CPU?

For bandwidth, it would be WAV: completely
uncompressed, full bitrate, 1440 kbps.

Note that FLAC was designed to be very easy to
decode, placing most of the processing power
requirement on the encoding step. It's assumed
that a track will be encoded on a typical PC, so
the encoding emphasis was on compression rather
than efficiency. Once compressed, the format is
designed to be extremely easy to decompress. Even
though no hardware FLAC players existed at the
time of its creation, the FLAC developers realized
that the efficiency would have to be concentrated
on the decoding first and foremost.

Thanks to that forward thinking, the Squeezebox
can play FLAC with only modest demands on its 250
MHz RISC processor.

joek wrote:
> I want to be able to stress test and am curious as
to which of the audio
> formats would provide a heavy load on the SB3?
>
> Would it be FLAC, since the SB3 would have to
uncompress a large audio
> stream before playing?
>
> Thanks!
>
>

--
___________________________________


Mark Lanctot
___________________________________

joek
2006-02-06, 14:58
Thanks for the replies and sorry for the confusion.

I am currently running two wireless SB3’s playing MP3’s (VBR highest quality setting) and have not experienced any network drops or skips in the audio. I feel confident my network, server and SB can easily manage these MP3 streams. I just wanted to make sure my environment (server, network, SB) as a whole can handle the most extreme cases when streaming audio.

Based on Mark’s reply, wav audio format is probably the most demanding on the network (and possibly server), since it is streaming at 1440 Kbps. Good starting point for me to run some wav streams through my configuration.

What do you mean by stress?
stress - try: test the limits of

funkstar
2006-02-06, 15:15
To place demand on the server you could set it up to transode from something like OGG (takes slightly more CPU to decode than MP3) and then send it out as MP3 with some insane quality presets. That should stretch your server.

What is your server hardware?
Are you using all this wired or wire less?
How many SBs are we talking here?

a completely wired network with hardware less than three years old and a single SB is going to cope with anything you can throw at it. Increase the number of SBs significantly, use old hardware and switch to wireless and you will very easily start to come across problems. Some of with will be easy enough to get round, others not so (wireless especially when you have a noisy signal area)

Mark Lanctot
2006-02-06, 15:39
If you can play WAV without issues, you can
definitely play FLAC.

WAV = 1440 kbps (off a CD), with overhead you'd
need 2000 kbps of bandwidth at least.

FLAC = 1000 kbps, 1500 kbps of bandwidth will do.

There's no reason to stream WAV though. You won't
gain any quality, it doesn't support tags and it
uses more hard drive space and bandwidth.

There's a good network test plugin here:
http://forums.slimdevices.com/showthread.php?t=18149.
If you can manage 2000 kbps at 100%, you will
have no problems with WAVs, but you'll only need
1500 kbps for FLAC.

joek wrote:
> Thanks for the replies and sorry for the confusion.
>
> I am currently running two wireless SB3’s
playing MP3’s
> (VBR highest quality setting) and have not
experienced any network
> drops or skips in the audio. I feel confident my
network, server and SB
> can easily manage these MP3 streams. I just wanted
to make sure my
> environment (server, network, SB) as a whole can
handle the most
> extreme cases when streaming audio.
>
> Based on Mark’s reply, wav audio format is
probably the most
> demanding on the network (and possibly server),
since it is streaming
> at 1440 Kbps. Good starting point for me to run some
wav streams
> through my configuration.
>
> What do you mean by stress?
> stress - try: test the limits of
>
>

--
___________________________________


Mark Lanctot
___________________________________