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Lossless to DAC without computer? - Page 3

post #31 of 37
8/1/08 at 1:51pm
Quote:
Originally Posted by Chri5peed View Post
Maybe in pretty perfect circumstances, but isn't wireless inherently more susceptible to interference?


Also, wouldn't the distance affect things. After all, there must be a limit, its not rated to work over thousands of miles. Surely the signal would degrade at some point?

A beam of light[Optical] will travel unhindered for thousasnds of miles. Why you can see a flashlight on the horizon.
Wireless only works over a hundred feet or so. There is no signal degrade. The data is buffered at the device, so there is no timing issue. The only time you have problems is if you have very bad wireless and there are dropouts. Then the music will pause and wait to catch up. At that point something is wrong with your setup.

You can also stream lossless music over the internet with no problems. There a program that you can access your whole itunes library and play it on your ipod as long as you have fast enough internet access. At this point the program can only queue up one song at a time but I'm hoping someone creates a streaming App that can perform as well at the Remote App.
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post #32 of 37
8/1/08 at 7:16pm
Typical live audio streaming of digital music files (even lossless rips) over the internet (or over your local wireless LAN) is not guaranteed to be bit perfect (but this falls into "who cares").

It works really well in practice, no question. But even with buffering and error detection / re-transmission (which is not used in many protocols) there are no guarantees (to get error free transmission in such cases may require the music to pause, which just substitutes one problem for another).

Airport / WiFi can be bit perfect, but only when you have moderate to low levels of interference ... which will usually be the case, I grant you. As a practical matter yes, wireless in your home can be as good as a digital cable. It can be bit-perfect. Digital cables can have problems too, btw.

None of these transmission problems are typically audible even when they do occur. That's why I said "who cares"!

But theory is fun, and theory says bits might be flipped.
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post #33 of 37
8/1/08 at 7:33pm
How does a flipped bit sound, and how many continuous flipped bits would have to be strung together before anyone could pinpoint it with certain accuracy?
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post #34 of 37
8/1/08 at 8:07pm
Quote:
Originally Posted by wavoman View Post
Typical live audio streaming of digital music files (even lossless rips) over the internet (or over your local wireless LAN) is not guaranteed to be bit perfect (but this falls into "who cares").
I thought that these are different, and Wi-fi from computer to media server uses point to point tcp/ip with error correction when audio streaming is broadcast UDP with no guaranteed reliability or ordering.
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post #35 of 37
8/1/08 at 9:47pm
Quote:
Originally Posted by StanleyB1
How does a flipped bit sound, and how many continuous flipped bits would have to be strung together before anyone could pinpoint it with certain accuracy?
Going on some pretty wild-ass assumptions here, but...

Assuming that a FLAC file is 16 bits/48kHz (typical audio content), and that the bitstream is a bit at a time, 16 bits per audio "frame", 48000 audio "frames" per second.

Then if you had 1 flipped bit, it would corrupt a single audio frame, which would sound "bad" for 1/48000 of a second. 1/48000 is roughly 1/50000 which is 0.02 milliseconds or 20 microseconds. If you flipped multiple bits in a row, it is possible that they all lie within the same audio "frame" and thus only one frame would still be corrupted. Or, if you had a steady stream of corrupted bits spaced around 16 bits apart for many bits you would start corrupting multiple audio frames, resulting in a sound "error" lasting multiple frames of 20 microseconds each.

How many 20 microsecond bad frames would you need? No clue, but i'm guessing probably a lot.

Note that this does not take into account error-correcting protocols in wireless transmissions and buffering, where a flipped bit (or bad packet) can be detected and resent without interrupting the flow of data due to the buffer. I'm not 100% positive but there's no way any multimedia streaming device (i.e. squeezebox or Airport Express) is operating without a buffer, and while I don't know the details of the 802.11 spec but I am pretty sure there must be some kind of error checking/error correcting code built into the protocol.

Ruahrc
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post #36 of 37
8/1/08 at 10:41pm
Try to flip bits in flac file and see how foobar2000 reacts, even that flac has pretty good corruption recovery the result will be quite drastic, something like ape will become plain unreadable. Now take something like mpeg, avi, mp3 or any other non pcm format that get decoded on the remote media server, no way they can process the file if there are "flipped" or lost bits.
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post #37 of 37
8/8/08 at 11:49pm
Quote:
Originally Posted by Random Access View Post
Option: Cheap Asus Eee portable PC (weighs around 2 pounds).
YouTube - Asus Eee PC 900
The Asus Eee PC is sweet super-portable laptop. Really nice engineering on that unit. It's price point makes it an excellent small portable computer, but I believe the largest internal drive is an 20GB SS so you'd have to either plug in and external (like a WD Passport) or wire/wireless it up.

For an all-in-one toy, check out the Flybook. It even takes a SIM card as a complete solution including cell phone. It's on my christmas list!
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