Re: [RE] Technical Feasibility
This needs a bit of elaboration, Kevin ...
In 1394 there is a common and very precise clock synchronization system (the
³cycle start² propagation mechanism). This is also used as a signal to start
launching isochronous packets scheduled for the current cycle.
1) Some of the protocols that use isochronous transport do not need any
further synchronization other than cycle number (the uncompressed video
modes used for machine vision, webcams, and video digitizers, for instance).
2) Many streams need better synchronization than that (audio, compressed
video), so they use the precise local cycle time value as a time stamp for
data arriving at the transmitter so that they can be replayed at the
receiver with a constant phase delay. This is used in all the "AV/C"
transports that are part of the IEC61883 family used by camcorders, DTVs,
DVCRs, DVDs, audio receivers, etc., etc.
So for all existing protocols used by 1394, the synchronization facility is
used for all protocols, although it may be used differently.
On 8/31/04 8:32 PM, "Gross, Kevin" <kevin.gross@CIRRUS.COM> wrote:
> One should consider whether you want synchronization to be part of the
> network. ATM's answer to this is no. 1394 says yes (and yet many of the media
> protocols used on 1394 re-implement synchronization).
>
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