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In Reply to: RE: Yes, I have applied your Toolbox already........... posted by soundchekk on August 06, 2012 at 06:44:13
I am running a Squeezebox touch with your mods and I have always thought that whatever format you stored your music in, it was streamed to the SBT in the same format. The buffer on the SBT is Huge, I have unplugged it and it played for quite awhile.
Can you explain to me why it could possibly sound different, if the same format was being streamed?Cut-Throat
Follow Ups:
"Can you explain to me why it could possibly sound different, if the same format was being streamed?"
If it sounds different it's likely to be very system dependent. It is much more likely to happen if the server is connected directly to the Touch than if it goes through an Ethernet switch or a router. The reason is that the switch/router buffers the Ethernet packets and reclocks them.
It is possible that electrical noise from the server is somehow polluting the Touch or downstream amplifiers, either through EMI coupled on the cables, through physical proximity or through power wiring. If you suspect this might be happening, it is very easy to test for this, just move the Ethernet switch/router and server machine to a different room and power them on a different circuit.
I suggest using only shielded Ethernet cables, cat. 5e or cat 6 throughout your network. This will minimize these cables acting as antennas. The cable connected to your server (and/or other computers) acts as an antenna to radiate noise, while the cable connected to your Touch acts as an antenna to receive noise. Noise on this cable and coming in the power wire will pollute the clock in the DAC, and this clock is in the audio signal path.
(All this assumes that the same bits are actually being sent out the server. It could be that there was "cockpit error" and the server was actually not converting into a common format.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
My post was unclear.....I have not experienced any sound difference between file formats. I was just confused as to why anyone else could.
Cut-Throat
Ok. All this is getting Off TOPIC.But let's finish this.
Obviously you have followed the endless discussions about that topic in
other parts of the virtual landscape.If you do the pcm conversion on the server, it's a fact that all files formats are sent as PCM data towards the client.
The "pull the cable" test is IMO too short and might cause weired error conditions and from my experience won't lead anywhere.
Run the tests I told you. Otherwise you'd be shifting conditions too much.
The Touch network buffer is a "streaming" FIFO buffer. Data is not copied in there in large data chunks. (Note: The actual audio buffer towards the audio interface is a different animal!! - size is usually a couple of ms)
That means there's a continous buffer management and continous interaction with the NIC (network interface card) ongoing. Somebody has to control all that. (I'm pretty sure that doing bulk copies of large data chunks instead of streaming could improve the situation)The NIC meets the stream prior to that buffer. It has
continously to work with the stream on a packet basis. It's a pretty tough job the NIC has to do.
You can easily test this, if you assign quite low priorities to the NIC associated interrupts. What you'll experience are "immediate" XRUNS on the audio interface, even with a buffer filled of 20s of data!!!
That tells us that the processor considers the buffer as a seperate element.
That's why IMO the huge buffer (20-30s) plays a minor role in the game.Now. Let's assume that slightest variations on load, noise spectrum (most people just talk about noise - but noise is a complex continously changing spectrum of everything) inside a computer - at almost any position (you'll find over here at AA that even SATA cable make a difference) - can have a certain impact on the audio interface. My guess would be that varying load conditions on e.g. a NIC, might have also some impact. (As I said earlier - my interrupt test has shown that there is a much more direct relationship to the whole, than the 30s buffer size would suggest) )
Obviously above also implies that there are certain changing conditions/variations seen on the network side. It's probably
similar to asynchronous DACs. What I mean here is, that if you (as the receiving end) ask for a packet it doesn't mean that you'll get it always in exactly the same time frame and packaging.
But again. Run the different files and make up your own mind. To test
this takes you less time then me writing this post... ...about things and speculations nobody is able to prove anyhow.Enjoy.
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::: Squeezebox Touch Toolbox 3.0 and more ::: by soundcheck
Edits: 08/06/12 08/06/12 08/06/12 08/07/12 08/07/12 08/07/12
OK, I Converted 1 Album Shelby Lynne, A Little bit of Lovin' in each of the 4 Formats. I took the first track of each format and loaded into the SBT Queue, so that I could switch back and forth very easily. On my system I could not hear a difference between any of the 4 formats.
I'll add that I have a brand new, very fast Computer with Gobs of Memory (16 gig)...I would imagine that the speed and capacity of the computer may make the difference for some that can discern a difference in the file formats.
I'll stick with Compression Level 5 as it saves disk space.
Cut-Throat
Yep. Fair enough.
Enjoy.
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::: Squeezebox Touch Toolbox 3.0 and more ::: by soundcheck
nt
Cut-Throat
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