[alsa-devel] [PATCH 10/39] firewire-lib: Add transfer delay to synchronized duplex streams

Takashi Sakamoto o-takashi at sakamocchi.jp
Mon Mar 10 14:43:26 CET 2014

(mar 10 2014 06:13), Clemens Ladisch wrote:
> The transfer delay is the offset between the frame in which the packet
> is transmitted and the intended presentation time.  This delay was
> already added by the device when it sent the input packets, so we
> don't need to send it again.

Exactly. Adding TRANSFER_DELAY for out-packets is needless...

IEC 61883-6 said:
"If a function block receives a CIP, processes it and subsequently 
re-transmits it, then the SYT of the outgoing CIP shall be the sum of 
the incoming SYT and the processing delay."

> The frame in which the out-packet will be sent is QUEUE_LENGTH
> frames later than that of the in-packet, so we need to adjust the
> SYT by that amount.  (However, 48 % 16 == 0.)

So basically we need to add nothing to SYT for out-packet.
This patch should be removed.


Takashi Sakamoto
o-takashi at sakamocchi.jp

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