Ray-CubeAce
lvl.4
United Kingdom
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fansfe82067d Posted at 12-4 01:57
Maybe I meant intermodulation distortion. When I was an audio engineer I got on with the job and didn't worry too much about the theory!! I will try once more to upload the plots I made of the audio measurements of the P2. Working the forum photo upload system seems to defeat me. But to put it in words, when you feed a gliding test tone into the P2 (gliding up), on playback, you hear more than one tone going up, and other tones going down. Not a good outcome. And yet in real-world situations, the P2 audio sounds just fine.
[Edit - I've now managed to upload my audio test charts and have created a new thread for the purpose.]
Hi.
Try making the charts using different wave forms. Sine, Saw, and square.and you should see different results at different sampling frequencies. It also shifts the sub harmonic distortion into different band areas with a sampling frequency of 192kHz possibly being the most acceptable to our hearing for those with equipment sensitive enough to reproduce the results accurately. How much of this we actually hear compared to what is seen on graphs or measuring equipment is debatable depending on the state of an individuals hearing.
The sampling frequencies that were selected for each video codec was arrived at by the consortiums at the time responsible for their development and limited by the tech available at the time. Early ADCs and DACs generated massive amounts of heat and needed huge heat sinks. My first Philips CD player had huge heat sinks but eventually the DACs blew up with an audible bang. Things had improved by the time DVD and digital video recording came along and the main reason the 48kHz sampling rate is used today for most video codecs. Again it relied on the state and capability of the hardware available at the time. Sometimes new specifications appear in competing markets but which is eventually adopted is down to who wins the largest market share.
I was also a studio recording engineer at Leeward Sound Studios in Soho London during the later half of the 70s producing radio and TV commercials. Those were analog days though, not digital.
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