[vdr] Re: addign STB-style timeshifting to VDR

[Lauri Pesonen <lauri.pesonen@firsthop.com>]

Emil Naepflein wrote:

>>I'm interested in implementing STB-like timeshifting features to VDR. 
>>What I have in mind is two features:
>>
>>* pausing live TV (and resuming it later on)
>>* configurable length instant replay (I.e. watch the last 10 seconds again)
>>
> 
> Good idea! But you probably opened pandoras box. ;-)


I'm getting that feeling ;) I think I'll write a requirements document 
based on all the ideas posted to the list and the list can then comment 
on that document. That way I can prioritize all the features and get at 
least something done.

> Everything below are ideas that would be nice.

> 
> 
>>I've being going through the VDR source now and then and I have a faint 
>>idea how to do this. What I don't know is how the features should work 
>>on a more detailed level. I have no experience with STBs that have these 
>>features, so I don't know how these features should work.
>>
>>A few questions:
>>
>>1. If you pause live TV
>>	- will the pause mode quit at some point, e.g. after 10 mins?
>>
> 
> There should be some user selectable time (preselected in setup). This
> also depends on the available disk space.


A user configurable setting sounds good. I think the current disk 
writing routines in VDR will take care of the latter suffestion.

>>	- is the stream recorded permanently (can replay the stuff later 	on) or is 
>>the recording lost after watching it?
>>
> 
> There should be an option to store it as permanent recording. The
> recording itself should run permanently on the currently selected
> channel. If I switch channel there should be an option to continue
> recording probably with a selection when the recording should be
> terminated. On the new channel the permanent recording should start
> again if a card is free of course. The priority of this permanent
> recording should be selectable just like for other recordings. So when a
> timer fires it may interrupt the permanent recording or not depending on
> the priority. May be permanent recordings can be setup just like timers
> with all the important parameters and kind of moving start and endtimer.


Ok. Should the recording be scheduled according to EPG info? That is, is 
I press pause while watching the news and the news broadcast ends before 
I start replaying the recording, should the recording stop when the news 
broadcast stops? I think it should, otherwise we will record live tv 
untill we run out of disk space...

 
>>	- can you move forwards and backwards while watching a
>>	timeshifted show?
>>
> 
> Yes.


Can you move backwards beyond the pausing point? I mean, should the 
instant replay buffer be added to the beginning of the recording?

 
>>	- What happens when you catch up with the live braodcast, e.g. 	
>>	by fast forwarding commercials? You should switch back to live
>>	tv, but do you notice it?
>>
> 
> When activating this mode you should always view the recording and not
> live. Passing past the end isn't possible. Only when stopping this mode
> or switching to a different channel you go into live mode. Switching
> channel is effectively a pause for the current channel. 


I think VDR should definitely switch back to live tv if you can catch up 
by fast forwarding during commercials etc. I mean that the switch should 
be transparent to the end user if possible.

>>	- The will have to be written to disk...?
>>
> 
> Yes, this will allow to keep the recording.


Ok. I was just wondering do people really want to keep recordings that 
start halway through the film/show/... But they might want to at some 
time...

 
>>2. Instant replay
>>	- do STBs have such a feature?
>>	- how long is the replay, e.g. 10 secs, 15secs?
>>	- since pressing the instant replay button is a basically the
>>	same thing as pressing the pause button, should the data
>>	buffered for the instant replay be saved to the beginning of the
>>	recording?
>>
> 
> Instant replay could be implemented just like the Pausing. The only
> difference would be the amount of time you go back.


I think that in order to do instant replay we need to store a buffer of 
the program stream in memory during transfer mode. When the end user 
presses the instant replay button, we go the to "pause live tv" state. 
The only differenc is that we begin playback from the beginning of the 
buffer and from the time we pressed pause. I think the buffer content 
could be dumped to the beginning of the 001.vdr file and the recording 
would then be appended to the end of the file. When showing an instant 
replay, playback should start from the beginning of the file. When 
showing a paused tv show, playback should start from the point where we 
pressed pause. Once playback starts after the instant replay or the 
pausing we are in replay mode from VDRs point of view and we can do all 
the things that are possible in replay mode. When the recording ends 
(i.e. we catch up with live tv or the shows has stopped), we move back 
to live tv.

the replay mode gets me to my next question: is it a problem that the 
remote controller goes to the replay mode as well? In the replay mode 
the up/down/left/right keys are used to control the playback and not 
channel switching as in transfer mode...

 
>>3. VDR buttons
>>	- should I introduce new buttons to VDR as a whole?
>>	- which ones of the old buttons couls I use (pause and rev are
>>	out of the question since they are already in use in transfer
>>	mode)
>>
> 
> The buttons should be usable just like in play mode. May be you must use
> one of the color keys to activate the pause mode from live mode.


here's my answer ;)


> I hope I didn't overwhelm you with ideas. ;-)


Not yet, I just have to write everything down.

> The most important thing for this is that it is easy to use.


I agree fully.

 
> Emil

Br, Lauri