iTunes Bit Rate suspicion thread.
Ok, the title is misleading but these are my questions and concerns.
I have setup quite an expensive audio phile setup ( actually 2) fed by a Core Duo mac mini.
The mac mini holds the high bitrate encoded songs, from 700 Kbps to 1500 kbps, ripped from CDs using Apple Lossless and AIFF encoding.
The mini then plays the songs via Airportto a Express Base Station and Simultaneously to a optical connected DAC.
Both outputs are Digital , that is I have a Benchmark DAC 1 connected to the Airport Express base station optical out and a MF DAC connected to the mac mini optical out.
i have Menu Meters installed and I can see the network htroughput when I stream songs to the Airport Express BAse Station. and...
SURPRISE.
When streaming 128 kbps songs or 1600 kbps songs the network troughput from the mac mini is APPROXIMATELY THE SAME around 100 to 110 kBytesps.
THERE IS SOMETHING VERY WRONG HERE !
The throughputs should be very different and proportional to the song bitrate encoding.
If one song contains 10 times more information stored that information should at least flow to the network at a multiple of the lesser information encoded song.
So, what gives ?
Are we being seriously wronged by Apple ? Please comment !
I have setup quite an expensive audio phile setup ( actually 2) fed by a Core Duo mac mini.
The mac mini holds the high bitrate encoded songs, from 700 Kbps to 1500 kbps, ripped from CDs using Apple Lossless and AIFF encoding.
The mini then plays the songs via Airportto a Express Base Station and Simultaneously to a optical connected DAC.
Both outputs are Digital , that is I have a Benchmark DAC 1 connected to the Airport Express base station optical out and a MF DAC connected to the mac mini optical out.
i have Menu Meters installed and I can see the network htroughput when I stream songs to the Airport Express BAse Station. and...
SURPRISE.
When streaming 128 kbps songs or 1600 kbps songs the network troughput from the mac mini is APPROXIMATELY THE SAME around 100 to 110 kBytesps.
THERE IS SOMETHING VERY WRONG HERE !
The throughputs should be very different and proportional to the song bitrate encoding.
If one song contains 10 times more information stored that information should at least flow to the network at a multiple of the lesser information encoded song.
So, what gives ?
Are we being seriously wronged by Apple ? Please comment !
Comments
Ok, the title is misleading but these are my questions and concerns.
I have setup quite an expensive audio phile setup ( actually 2) fed by a Core Duo mac mini.
The mac mini holds the high bitrate encoded songs, from 700 Kbps to 1500 kbps, ripped from CDs using Apple Lossless and AIFF encoding.
The mini then plays the songs via Airportto a Express Base Station and Simultaneously to a optical connected DAC.
Both outputs are Digital , that is I have a Benchmark DAC 1 connected to the Airport Express base station optical out and a MF DAC connected to the mac mini optical out.
i have Menu Meters installed and I can see the network htroughput when I stream songs to the Airport Express BAse Station. and...
SURPRISE.
When streaming 128 kbps songs or 1600 kbps songs the network troughput from the mac mini is APPROXIMATELY THE SAME around 100 to 110 kBytesps.
THERE IS SOMETHING VERY WRONG HERE !
The throughputs should be very different and proportional to the song bitrate encoding.
If one song contains 10 times more information stored that information should at least flow to the network at a multiple of the lesser information encoded song.
So, what gives ?
Are we being seriously wronged by Apple ? Please comment !
There are so, so many things that could be the case. I don't know much about how the Airport Express works, or for that matter 802.11g, but I do know about USB. It's likely that they use similar communications techniques.
In other words, there are a number of different ways a digital connection can be trafficked. The first is basic, asynchronous packets. Whenever enough data is ready, it goes. This is fine if you can guarantee no collision (two sources try to send data at the same time over the same medium). In the case of audio, timing is kept strict. A data packet cannot collide, or else there will be a skip. It's highly believable that the setting the Airport Express uses for audio just assumes the worst case data size (CD audio) and bases the size of its packets on that.
If it matters that much to you, download and read the 802.11g spec. I bet the answer is in there.
There are so, so many things that could be the case. I don't know much about how the Airport Express works, or for that matter 802.11g, but I do know about USB. It's likely that they use similar communications techniques.
In other words, there are a number of different ways a digital connection can be trafficked. The first is basic, asynchronous packets. Whenever enough data is ready, it goes. This is fine if you can guarantee no collision (two sources try to send data at the same time over the same medium). In the case of audio, timing is kept strict. A data packet cannot collide, or else there will be a skip. It's highly believable that the setting the Airport Express uses for audio just assumes the worst case data size (CD audio) and bases the size of its packets on that.
If it matters that much to you, download and read the 802.11g spec. I bet the answer is in there.
Yes, I think this would be a plausible explanation.
But even if there is some bit stuffing on the TCP side, we're talking about more than 10 times more digital payload...
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This is very weird and I don't like it. I have upwards of 6000 USD DAC-AMP-SPEAKERS connected to the Airport Express and there is almost no noticeable difference between the 128 kbps and 1700 kbps encoding. I love the synchronous stream of itunes to multiple setups like these , though...
Time to whip out the oscilloscope and start measuring ????
Read about it here (PDF).