Aug
6
Digital Music and Order Flow, from Jim Sogi
August 6, 2012 |
Digital music uses different algorithms that reduces the spectrum of pure sound to a small sampling. As a result the sound is always "hollow" and lacks the fidelity of live or even analog vinyl. Turning up the volume or boosting the bass doesn't cure the problem. I remember when we would spin the vinyl in the old days, everyone would get up and dance. There was more feeling. Some of the algos boost the prominent parts of the track and hide the back tracks. Things are lost.
In a similar way, IB uses some sort of algo to reduce the bandwidth of the order flow in order to keep prices current for execution. Investigation to determine if it is a proportionate reduction of the bid/ask order flow, showed it is not. Use of the IB data flow will screw up order flow calculations. Russ wrote about this some years ago. A lot is lost, but even in fast markets IB's price seem to keep pace pretty well. Its hard to tell when your broker quotes lag behind your data feed what is going and results in fills outside the apparent inside market.
Jeff Sasmor writes:
A lot of what you hear has less to do with the digital process that's used to compress the audio but with preprocessing to make things sound better on ipods and such. Hard to believe? In the past I worked at a major NYC recording studio and we used to have tiny speakers so people could see what a recording would sound like on a junky transistor radio or an AM radio.
It's the compression and other processing that makes most of what you're complaining about. It's also dynamic range. On a standard CD you have 16-bit audio which isn't mpeg encoded or anything like that. But 16 bits is only 96 dB dynamic range which isn't enough for you to hear quiet sounds adequately without having loud sounds be distorted. So sound was routinely "compressed"; not in the sense of mpeg and aac (which are perceptual encoders) but rather dynamic range compressed to make quiet sounds louder and loud ones quieter. That's most of what people found objectionable when CDs were first introduced (and even now since the tech is more or less the same).
Perceptual encoders are not worth explaining in detail, but they throw out sounds you probably wouldn't hear as part of the process. It's actually sort of obnoxious…
Modern uncompressed audio at 24-bits, if encoded that way originally and not messed up by mpeg or aac or other processing is much better than vinyl with no clicks and pops.
But with all the emphasis on downloads and the fact that most people are listening on systems that can't reproduce much, and the other fact that most people don't care, 24-bit just isn't viable as a product.
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