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Packet Loss Leads To Jitter, which in turn leads to sound degradation .: Do Cables Matter?

post #1 of 5
9/20/12 at 12:19am
Thread Starter 

Before you post, this is an open discussion.  Any supported arguments are welcome, but if all you're here to do is say "No.", or something unintelligible in general, no thanks.

 
Anyways,

 

Question #1 - Where does packet loss happen most: Across a network, such as through Airplay, or over a physical interconnect, such as USB or optical?

Question #2 - If packet loss is nothing more than a packet of information failing to reach its end destination (ie Airplay to Receiver), does that in turn lead to jitter?

 

If jitter is viewed as nothing but packet loss across a network, it seems clear that packet loss leads to jitter, which in turns harms sound quality.

 

Here comes the big one:

 

If there were "packet loss" across a cable, be it USB or optical (any digital interconnect), wouldn't this in turn lead to jitter, therefore harming sound quality?

 

And, lastly, going back to question #1, if the assumption can be made that timing errors, aka jitter, and for the point of this post, packet loss, lead to sound quality harm, where do we truly lose less information?  Across a network such as Airplay, or through a cable itself?  My assumption would be a cable; nothing beats a physical interconnect.  Then again, what is the average packet loss across a network of a standard FLAC file in comparison to a physical digital interconnect?

 

Random Thought,

-I3

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post #2 of 5
9/20/12 at 3:55am
Quote:

Originally Posted by I3eyond View Post
 

Question #1 - Where does packet loss happen most: Across a network, such as through Airplay, or over a physical interconnect, such as USB or optical?

Question #2 - If packet loss is nothing more than a packet of information failing to reach its end destination (ie Airplay to Receiver), does that in turn lead to jitter?

 

S/PDIF is not packet based. In the case of a network stream, if there is an error transmitting a packet, it should be sent again. At the receiving end, the player buffers the audio data, so if it arrives in time, there will be no error in the playback. If there is an error that cannot be corrected and/or data is not received fast enough (the buffer underruns), the result is not jitter, but more obvious artifacts like skipping, pops, etc..

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post #3 of 5
9/21/12 at 10:15am
Quote:
Originally Posted by I3eyond View Post

Before you post, this is an open discussion.  Any supported arguments are welcome, but if all you're here to do is say "No.", or something unintelligible in general, no thanks.

 
Anyways,

 

Question #1 - Where does packet loss happen most: Across a network, such as through Airplay, or over a physical interconnect, such as USB or optical?

Across large networks.

 

 

Quote:

Question #2 - If packet loss is nothing more than a packet of information failing to reach its end destination (ie Airplay to Receiver), does that in turn lead to jitter?

If the packet doesn't get retransmitted or if it does but not in time you'll experience an audio glitch such as a pop or click.

If it does get retransmitted in time the buffer on the receiver's side will counter jitter.

 

 

Quote:

If jitter is viewed as nothing but packet loss across a network, it seems clear that packet loss leads to jitter, which in turns harms sound quality.

A truly lost packet leads to clearly audible audio glitches.

 

 

Quote:

If there were "packet loss" across a cable, be it USB or optical (any digital interconnect), wouldn't this in turn lead to jitter, therefore harming sound quality?

Then the cable is broken and needs to be replaced.

 

Short answer: the cable doesn't matter as long as it's not broken.


Edited by xnor - 9/21/12 at 10:17am
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post #4 of 5
9/21/12 at 11:48am

Jitter is a timing deviation from periodicity, causing information to be misaligned in the time domain.

Packet loss would be the loss of information.

If you were losing information entirely, jitter wouldn't matter at that point. Actually the question should be "how much jitter could result in the loss of data?".

With regards to cables, if you were experiencing packet loss due to the cable, your cable is broken and it would be extremely obvious.

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post #5 of 5
9/22/12 at 1:40pm

Most packet loss is caused by congestion in the network. There is basically no packet loss over the a single piece of cable. Here's an experiment. Turn on Skpye or whatever VoIP program. In the busy hours you'll experience some packet loss which result in pretty poor quality. Switch to a cable and see if it helps. I can guarantee it will not.


Edited by dvw - 9/22/12 at 1:42pm
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