[mythtv-users] MythTV questions...

Bill Chmura Bill at Explosivo.com
Wed Apr 7 16:52:30 EDT 2004


When I use my system for this there is approximately a 1-2 second delay 
between channels as the system buffers up some video to use.  I am not sure 
if you can set the amount to buffer before starting to show it.

This is on a 7200RPM drive with hardware encoding on the PVR and a 2.4 Ghz 
machine.

30 seconds sounds really long to me, but I have only run it on this system


On Wednesday 07 April 2004 04:35 pm, Dex West wrote:
> This delay between changing channels really worries
> me.  Can people please tell me approx. how long this
> delay on a working system is?
>
> On Tivo channel changing happens immediately.  Is this
> delay between frontend and backend configurable?
>
> Thanks
>
> --- Eduardo <mythtv at ease.mb.ca> wrote:
> > John Sutherland said:
> > > Hi guys/gals..
> > >
> > > I just setup and got working a basic mythtv box,
> >
> > and I have some
> >
> > > questions..
> > >
> > > First, a little about the system it its on.. I'm
> >
> > using this box more of a
> >
> > > proof of concept for myself.. It is a Pentium II
> >
> > 400Mhz, 128M, PVR-350,
> >
> > > and a "broken" 40G drive.. By "broken" I mean that
> >
> > I can not get more than
> >
> > > 2M/sec rates from hdparm -t.. The drive works, its
> >
> > just slow... I'm using
> >
> > > the 350's TV-Out, and for a distrib, Gentoo...
> > >
> > > Now for the questions...
> > >
> > > 1) I've noticed that channel changing is
> >
> > ---slow---.. Nearly 30 secs to
> >
> > > change the channel... I'm assuming its either the
> >
> > slow drive, or the slow
> >
> > > processor.. Which do you think it is?
> >
> > There is always a delay as the backend buffers up
> > some of the video (more
> > on that later). 30 seconds seems very long. Unless
> > everything is playing
> > VERY SLOW, and this is just adding to the channel
> > change time.
> >
> > > 2) What is the difference between the frontend and
> >
> > the backend? I haven't
> >
> > > seen a good description of what both of them
> >
> > really do... Does the backend
> >
> > > do the storage?? If I move my backend to another
> >
> > (much faster) machine,
> >
> > > would that solve the channel changing slowness??
> >
> > Backend controls the tuners and records the shows.
> > Even when you are
> > watching "live tv" you are really recording a show.
> > If you didn't you
> > couldn't jump forwards and backwards. All the
> > storage takes place on the
> > backend. The CPU power it needs is for doing the
> > encoding.
> >
> > The frontend accesses the backend to receive the
> > video streams. So when
> > you change the channel on a frontend, it tells the
> > tuners on the backend
> > to change. The CPU power it needs is for decoding
> > the video data.
> >
> > These rules all go out the window for all the other
> > plugins, mythmusic,
> > mythvideo, etc, which all run on the frontend and
> > don't have that nice
> > "client server" behaviour. This is why everyone
> > seems to map drives from
> > the frontends to the backends. The backend usually
> > has all the storage
> > capacity, so people put their images, videos and
> > MP3's on the backend.
> >
> > Note, the backend and frontend can be the same
> > machine. You just need the
> > CPU power to do the encoding and decoding at the
> > same time. Your 400 is
> > pobably slow, because it has to do encoding and
> > decoding at the same time.
> >
> > > 3) When using the TV-out on the 350, how's it
> >
> > really work? Does it read
> >
> > > the input from the tuner, then store it to disk,
> >
> > then read it, and send it
> >
> > > to the tv-out? (kinda related to the previous
> >
> > question I guess)
> >
> > It is encoded by the hardware encoder on the PVR,
> > stored to disk, and then
> > decoded through the hardware decoder on the PVR. The
> > PVR takes away lots
> > of CPU load on both encoding and decoding.
> >
> > > 4) Has anyone coded up a burner plugin? To burn
> >
> > DVD's, VCD's from recorded
> >
> > > video? Or even music? If not, I might consider
> >
> > writing one..
> >
> > Dunno on this one. Probably.
> >
> > > Thanks guys/gals!
> > >
> > > --John
> > > --
> > > --John
> > >
> > >
> > > _______________________________________________
> > > mythtv-users mailing list
> > > mythtv-users at mythtv.org
>
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
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>
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>
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-- 

Bill Chmura

w. http://www.fistfullofcode.com
w. http://www.explosivo.com

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