Re: [Jack-Devel] About ALSA drivers for Firewire sound devices

>> >With non-clock-synced devices these days, it is better to use JACK's own
>> >capability for handling multiple devices. But since all the firewire
>> >devices on a chain share the same clock, this seems right.
 >
> While the firewire bus provides a synchronous bus clock (primarily used for
> timing data transfers), very few firewire audio devices can make use of this
> to derive an audio clock.  In a vast majority of cases, to achieve clock
> sync two firewire interfaces on the same firewire bus still need to be
> synced either via wordclock (best) or optical ports (the fallback in the
> absence of wordclock I/O).

My drivers don't support this type of synchronization: some devices in 
the same IEEE1394 bus, drivers decide a sync master from the devices 
then the others are sync slave, the drivers receive timestamp in packet 
from master and transmit the timestamp in the packet to the others.

And my drivers don't support this type of synchronization: some devices 
in the same IEEE1394 bus, drivers connects between them to transfer 
synchronization packets each other.

The reasons are:
1.I have never seen public specifications which describe this type of 
synchronizations.
2.I have never seen devices which support this type of synchronizations.

I guess that it was difficult for hardware vendors to implement this 
ideal synchronizations correctly, or sellers were not interested in.


Regards

Takashi Sakamoto
[hidden]

1391617195.27701_0.ltw:2,a <52F264A2.90903 at sakamocchi dot jp>