Hi Johannes,
On Tue, 2005-07-26 at 11:23 +0200, Johannes Stezenbach wrote:
> Andreas Oberritter wrote:
> > if you have multiple displays and/or Picture-In-Picture decoding, then
> > you have to define one PCR per display as master for vcxo control.
> >
> > Therefore I propose the following simple interface:
> >
> > struct dmx_stc_mapping {
> > unsigned int clock_num;
> > unsigned int pcr_num;
> > }
> >
> > #define DMX_SET_STC_MAPPING _IOWR('o', 51, struct dmx_stc_mapping)
>
> I think the naming is a bit misleading, because in your first
> sentence you say that this is about setting the "master for
> vcxo control". I.e. (if I get it right) you have one 27MHz
> crystal, but two PCR/STC. Obviously the vcxo can be synced to
> only one of them, so you have to choose (for PiP usually the
> one with the bigger picture).
>
> How about:
>
> struct dmx_vcxo_control {
> unsigned int vcxo_num; // in case you have more than one vcxo
> unsigned int pcr_num; // which PCR to sync the vcxo to
> };
>
> #define DMX_VCXO_CONTROL _IOWR('o', 51, struct dmx_vcxo_control)
>
> or maybe DMX_SET_VCXO_SYNC_SOURCE?
You are right, "stc" was quite confusing.
I've been told that using a VCXO is not the only way to synchronize the
transmitter and receiver clock, so how about your proposal with "vcxo"
replaced by the more generic "clock"?
Regards,
Andreas
