[mythtv-users] Firewire Channel Changing on SA 4250HDC?

Rob Burton phantom1000 at gmail.com
Thu Oct 4 01:30:20 UTC 2007

Has anyone had any luck with getting this STB to recognize channel change

I've tried the firewire_changer code that Jim provided, and I'm getting
exactly the same results that Brian got; failure on the individual buttons,
and reported (but not actual) success on the the tune method.

I've modified the sa3250ch code to allow me to send hex commands to the STB
and have been using the (admittedly old, but freely available) AVC 3.0 spec
(http://pbx.mine.nu/dvhs/AVC_30.pdf), the avc1394.h file, and various web
pages as guides.

I've been tinkering away at this for the last week, and so far the only
thing that has worked is detecting the current power state of the STB:

When power is off (via the power button on the STB):
AV/C Command: cmd0=0x01ffb27f cmd1=0x00000000
Response: 0x0CFFB260 cmd1=0x00000000
* *
When power is on (via the power button on the STB):
AV/C Command: cmd0=0x01ffb27f cmd1=0x00000000
Response: 0x0CFFB270 cmd1=0x00000000

I believe this box is supposed to meet the requirements of FCC-03-225 (
which  requires STB's to support the pass through tune command as described
in the non-freely available CEA-931-A spec. I am willing to purchase
CEA-931-B (which superseded CEA-931-A) in order to try to go further.

I can't believe that I'm the first person to work though this (I'm not that
original ;) ). Does anyone already have this spec? I am aware that the spec
is copyrighted, and I'm not looking for a free copy, but does that prevent
implementing it? What am I missing?

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