[mythtv-users] Why does going to live TV take so long?

[Marco Nelissen]

>Tivo's buffer is about 7 seconds as well. From memory, my Series 1
>Tivo had a 7second buffer. The difference is in how MythTV and Tivo
>handle the channel change from the perspective of the user. Tivo would
>change the channel on the tuner while still playing the current show
>until the new channel change had completed and then begin playing the
>new show.

That may have been the case with the Series 1, but it's definitely
not the case with Series 2. My Series 2 DirecTivo stops playing the
current channel right away, and shows the new channel program info.
Then about a second later, the new channel's video is shown.
I haven't used my standalone Series 2 Tivo in a while, but I remember
it being similar. Definitely no 7-second wait to change channels.

> MythTV orders this differently. When you tell Myth to change
>a channel it stops the currently playing channel, changes the tuner
>and when it gets a stream begins to play. One could alter this
>perception of time by making Myth continue to play the current channel
>until the next channel's mpeg file begins filling up with data. The
>only issue will arise when the time buffered in the current channel is
>not enough to make up for actual tuning time. ie if the tuner takes
>6seconds to change channels, lock and begin writing an mpeg file but
>you only have 3 seconds of buffer in the current channel then you will
>still have 3 seconds of "dead" time.

Well that's the question then: does it really take 6 seconds for the
tuner to tune to a channel? The time to change the channel on a DVR
should be only a fraction of a second longer than the time it takes
the tuner to tune to a new channel, but If PC-based tuners are that
much slower than the tuners you find in TVs (or Tivos) then that would
certainly explain why MythTV takes so long.
I doubt that's the case though, since someone mentioned earlier that
MythTV has a 3-second buffer of data. If that's the case, it would
account for the bulk of channel change time.

Marco