[mythtv-users] DVB issues

Brian May bam at snoopy.apana.org.au
Sun Mar 21 16:28:47 EST 2004

>>>>> "Ville" == Ville Vehvilainen <buddha at cs.tut.fi> writes:

    Ville> The frontend does not cope well with this situation. It
    Ville> does not accept any keyboard input during the tuning
    Ville> attempt, and eventually returns to the menu. Subsequent
    Ville> attempts to watch liveTV result in the same behavior.

Hmmm... Wondered what happened if you waited long enough... Normally I
get impatient and abort with Ctrl+C at the console.

    Ville> Because of that, and since the backend is fixated on that
    Ville> channel, there seems to be no easy way to tune to another,
    Ville> working one!

    Ville> To get the system back running I have to use the channel
    Ville> editor or hack the database so that the channel in question
    Ville> is one that is actually showing some programming.

Been there, done that!

Another way is to:
1. stop backend.
2. change "first channel" for DVB card, with mythtv-setup or database editor.
3. restart backend.

However, killing the backend like this is rather inconvenient... (I
have the TV in my lounge room display live from my analog card,
forcing MythTV to allow me to show live from the DVB card in my
bedroom; when ever I reset the backend I have to reset everything
else, too).

There should be some way of changing the channel (eg. with command
line utility) via the backend without trying to receive a video

Also, on the topic of DVB:

* we have radio feeds broadcast via DVB here. I stupidly tried to
  setup one with no video PID but an audio PID. Same problem
  reoccurred as above.

* MythTV needs to realize that things can go wrong, and it shouldn't
  die in a heap if for some reason it can't get any signal. Just
  display a message "No signal received" and try to go back to a
  working channel. Obviously there will be cases where no channels
  work (eg. some fool unplugs antenna), it needs to be able to
  gracefully cope with this too. I am using 0.14, this might be fixed
  in CVS?

* Same DVB channels have no analog equivalents and some analog
  channels have no DVB equivalent. I suspect MythTV can't cope very
  well with either case. eg. I have a suspicion that MythTV would try
  to record channel 31 on DVB, as DVB is preferred for recordings,
  even though channel 31 doesn't have any DVB settings defined (not

* MythTV *really* needs to be able to load DVB channels directly from
  channels.conf file; this could be loaded directly into the database
  (some table may be required to map channels from channels.conf into
  MythTV channels) or by the backend directly reading the
  channels.conf file. Probably the first better fits into the existing
  MythTV model, I would image it shouldn't be too difficult either. Is
  anybody doing anything like this? I don't want to re-invent the

* Aspect ratio. DVB is wide aspect ratio. This displays fine on a
  computer screen. When displaying it on TV using the decoder in a
  PVR350, the decoder "squashes" the image up to fit into standard
  4:3, which is obviously wrong. Pushing "W" cycles through modes
  without any effect. Ideally I would like 2 modes:

  1. which leaves the height as is, but chops of the sides (ideal for
     shows which are broadcast in wide format, but really only 4:3 and
     the sides are black).

  2. Reducing the height to prevent picture distortion when showing
     full image.

  I have no idea of the capabilities of the PVR350, but I would hope
  that at least 2 is possible.

* Issues with not being able to change channels need to get fixed in
  latest DVB driver code (assuming they haven't already been fixed in
Brian May <bam at snoopy.apana.org.au>

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