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TheLastMan
2012-05-16, 09:38
Technical question: does the Squeezebox Receiver have some "set" streaming rates? I ask this because I have been trying to optimise the position of my Receiver relative to my wireless router and using the Network signal graph utility on the Controller. It seems to me that the Duet will stream at one of a few pre-fixed rates depending on how strong the signal is. In other words with a given signal strength/quality the streaming gives a flat topped graph. Improve the signal and it doesn't gradually rise but takes a "step up" to the next level.

From my experiments I have found set levels at roughly 200 Kb/s, 400 Kb/s 800 Kb/s and 1500 Kb/s. I don't have the exact numbers, these are just estimates from the very small graph. In each case the graph has a flat top but if you improve the signal it will step up one level. If you have a marginal signal it tends to start high, then steps down and up a bit before finally settling at a particular rate.

My problem was I had to move the Receiver from a position with a good signal to one with a poor signal. I used to get a constant 1500 Kb/s in the old location which was great for streaming FLAC files. When I checked it at the new location it would only give about 800 Kb/s.

Luckily that still seems to be enough to reliably stream FLAC encoded at compression level "5" which is what I used for most of my rips.

I used to think that you needed 1,400 kbps to stream FLAC but thinking about it the formula is 44100 (Hz) x 16 (bits) x 2 (channels) = 1,411,200 bits per second. This is compressed roughly 60% in a FLAC file giving a streaming rate of 846,720 bps or 826 Kbps.

Presumably the set streaming rate I am seeing is designed to be enough to cope with FLAC. Similarly the bit rate of 400 kbps is probably designed to cover 320kbps MP3 files and the 200 kbps rate covers 196 or 128 kbps MP3s.

Is that others experience?