[mythtv] suggestion for rewinding in mythtv

[Derek Atkins]

Damion de Soto <damion at snapgear.com> writes:

> Hendrik,
>> It still should be possible to rewind after switching the
>> tv-channel. That makes it possible to look if there is something
>> else on tv at a different channel first, before watching a recorded
>> livestream-buffer from an hour ago.
> I've thought about this a few times, and rewinding over channel changes does
> seem a bit strange, but I think it could work.
>
> I guess you've got to then decide which channel the 'live' tv stream
> should still be on, and what then happens if you try and change
> channels again whilst in a previously rewound stream (that already
> contains a channel change).
> Does it go to the end of the current 'live recording' and change channels there,
> or should it cut-out what's currently in between what's currently
> being watched, and real-time.
>
> lots of confusing and non-intuitive decisions.

Doesn't seem confusing to me at all.. Indeed I found the existing
behavior to be non-intuitive..  If you consider the input to be a
stream, a channel change is just something that happens "upstream"
from mythtv..  I.e., it's just performing a bunch of read()s from the
video device, and a channel change is just an ioctl() to the device.
The fact that the frontend is "behind" real-time shouldn't matter.
IMHO a channel change should just continue from where in the ring
buffer it was already writing.

In other words, the videocard input should always put data at the
end of the ring buffer.  Channel changes shouldn't affect that.
Where the frontend is reading from the ringbuffer shouldn't affect
that, either.

As the channel change is just an ioctl I've always found it strange
that the ringbuffer resets itself during a channel change.

-derek
-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available