[mythtv-users] Changing channel delay theory

[Bob Wiegand]

Alberto Alonso wrote:
> OK, I read the docs that say that the buffering of 4 seconds
> is needed so that fast forward and rewind work.
> 
> I am hoping that someone will help me understand why. If the
> buffer doesn't have any back data I can understand the operations
> to just leave the viewing cursor at the present position. However
> if during the viewing they user decided to pause this would start
> filling up the cache. This would then have the effect of being
> able to forward/rewind as needed.
> 
> Any explanations?
> 
> Thanks,
> 
> Alberto

When you watch TV what MythTV is actually doing is:

- Encode TV signal
- Save encoded data to disk
- Read encoded data fom disk
- Decode data
- Display decoded data on TV

All this processing takes time - that's why there is a few second
delay when you change channels.

If the live TV signal was displayed directly without delay then you
would have a problem when you tried to pause, fast forward or rewind.
There would be a delay waiting for the decoder and the time would skip
backwards a few seconds.

Putting the delay at startup avoids a discontinuity during playback
and it was also probably easier to implement.

--
Regards,
Bob