quartz: Set a default sync source on the filtergraph
chris.kcat at gmail.com
Fri Mar 14 20:37:49 CDT 2008
On Friday 14 March 2008 04:25:02 pm Maarten Lankhorst wrote:
> Use the fallback system IReferenceClock, unless the app comes up with
> its own clock.
This doesn't look right. According to MSDN, the clock used when Run is called
is chosen by the following algorithm:
1- The app called IMediaFilter::SetSyncSource
2- A live filter source is connected to the graph and supports the
3- Any filters support IReferenceClock, starting with renderers and
going "upstream" (following pin connections to the source), and falling back
to disconnected filters if still nothing. Normally, an audio renderer would
be selected here.
4- If still nothing, use the system reference clock.
I don't think SetDefaultSyncSource should should just jump right to the system
clock. As far as I can tell, you need to hold a reference to a clock, and a
bool saying if it's custom set (as even NULL can be a valid custom override).
When Run is called, if no custom override is set, it would release the
current set clock (if any) and check as steps 2, 3, and 4 describe.
So really what the function needs to do is release the current set reference
clock (if non-NULL), clear a custom-override flag (while SetSyncSource sets
the custom-override flag and holds a reference for non-NULL filters), and
check steps 2, 3, and 4. So something like:
this->ref_clock = clock;
this->custom_clock = TRUE;
this->custom_clock = FALSE;
...do steps 2, 3, and 4...
this->ref_clock = selected_clock;
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