[linux-dvb] Re: driver switches back to PAL mode after 2 hours?

[Johannes Stezenbach <js@linuxtv.org>]

bob wrote:
> C.Y.M wrote:
> >bob wrote:
> >
> >>If I szap to a NTSC video channel and then to an audio channel and 
> >>exit szap I notice that the video (blank screen) goes back to PAL 
> >>mode, I think because I can see the blank screen "rolling". Szapping 
> >>to the NTSC channel will put it back into NTSC for another 2 hours.
> >>
> >>Has anyone else noticed that and is there runtime or compile time 
> >>option to keep that from happening? Or it is hardwired in the dvb card?
> >With this patch, once you lock on to an initial NTSC signal, it will 
> >stay that way.
> >
> >--- dvb-kernel/linux/drivers/media/dvb/ttpci/av7110_av.c.old 
> >2004-03-23 09:56:53.000000000 -0800
> >+++ dvb-kernel/linux/drivers/media/dvb/ttpci/av7110_av.c 2004-05-04 
> >01:58:45.000000000 -0700
> >@@ -1424,7 +1424,7 @@
> >
> > int av7110_av_init(struct av7110 *av7110)
> > {
> >-       av7110->vidmode = VIDEO_MODE_PAL;
> >+       av7110->vidmode = VIDEO_MODE_NTSC;
> >
> I have this patch in and it still doesn't seem to start up in NTSC mode. 
> I event added a printk after the line av7110->vidmode = 
> VIDEO_MODE_NTSC;  to make sure that it was executing this (it was). I 
> can easily szap it into NTSC however.

The firmware sets the video mode based on the framerate field from
the last decoded MPEG frame, and it defaults to PAL (hardwired).
When the MPEG decoder is idle, the driver can use av7110_set_vidmode()
to set the video mode. Maybe you can come up with a patch to call this at
the right time during initialization to force NTSC.

As to why the mode changes back to PAL after two hours: I've no idea.

HTH,
Johannes