[TVHeadEnd] Hint - Timeshift while recording !

If it helps to know, I'm also very interested in timeshifing in general, not only during recording, and yes, the person who I'm interested in the feature for is my lovely wife :-)

I'm not sure if timeshifting using the back end will ever be effective as through XBMC. Basically, a timeshifting mechanism writes the incoming stream to the disk
* Each packet is appended to the file
* When reaching a certain time limit, packets from the beginning of the file are overwritten (rotational data file)
* Every time the channel is changed, the file is removed

The file doesn't have to be compressed at any time as you might want a recording to be. It's very similar to moving back on a file played on YouTube, but with the rotational behavior.

I think the basic use cases are fairly well understood and the high level concepts of how it would work etc...

What's trickier is how it needs to be implemented in practice. This is where my current knowledge falls down.

There also needs to be interaction between XBMC and the backend's to control how this will happen etc.. Since current model (at least for TVH) simply doesn't include the concept of going backwards/forwards in a live stream, its treated very differently to a recording.

Just out of experience (from vdr project), there are 2 things what people are referring to as Timeshift.

1.) pressing "Pause" during live-tv, which starts a recording, and gets seemless played. Or watch any still ongoing recording. (VDR with its own frontends is capable of this, i.e. its one of VDR's features) - in XBMC-PVR is missing:
- the Pause-Key functionality
- not all pvr addons refresh the recording index - so playback of the recordings ending too early (at least last time i tried xvdr/vnsi)

2.) constant Buffer of x minutes running on harddisk, which enables you to pause/rewind x minutes if you watch that station long enough. The request for this one constantly pops-up and there is some patch in development for VDR. Here the community normally divides in 2 halfs. One group thinking its a must have, the other group thinking its a waste of resources (hard disk wear, electricity, cpu ....) - also handling of this is a constant point of discussion (should this be handled like live-tv, should it be handled like a recording, should a new handling in user interface be introduced). Such a buffer would also introduce a lot of buffers to the live tv - which does not help in getting the best usability.

The first one could be fairly easy - though i don't know the dev schedule of xbmc pvr - i hope its being worked on after xbmc-pvr is in xbmc core (i mean we are waiting 2-3 years now - extending scope is nothing which will help to change this) - the second one - is nothing i care about - if it will be implemented, i hope its done being optional feature.

@cubicle: i think no pvr backend is compressing ANY recording at any time - its writing to disk whats coming from the stream - as we are mostly talking about digital tv here. It gets compressed before distribution happens.