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Old 23rd June 2006   #11
DrDeltaM
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Quote:
Originally Posted by thomashenry
I'm not so sure. FW isoc streams also contain a lot of data which is formatting data in addition to audio. It's not nearly as simple as your maths suggest. I'm not sure about the exact configuration of isoc transmitters on the FF, but assuming it is 2 transmitters of 14 channels in each direction, the required bandwidth at 48kHz would be approx:

each packet:
14 channels * 8 samples * 32 bits per sample (even for 24 bit audio) + 64 bits of CRC + 96 bits of header data = 3712 bits per packet

then

size of packet x 4 transmitters x 8000 packets per second

= approx 14.2 meg/second.
Yes, I didn't take this into consideration, I was purely counting the audio data, not a tech guy to know all those firewire protocol details, my mistake :-) It's probably why some companies like MOTU choose to have their own format running of a firewire-type of connection.
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