How does 'delayed viewing' work?

[Steerpike]

Just a technical curiosity question, I guess.

If I "pause" live TV, then resume, I'm actually watching from the buffered data on the hard drive. This suggests that the recorder application is writing data to the buffer, while the viewing application is reading from the same buffer (different location within the buffer, obviously). From a technical standpoint, how is this achieved - how does the process avoid running into file locking issues?

I imagine the recording application would have to have some kind of a write lock on the buffer file, and also that the written data may be buffered in memory and not flushed to the actual disk right away; both of which could cause problems with the viewing application. Obviously, if you are designing the recording program, the viewing program, and the file buffer, you take all this into account and 'make it work' ... just curious how it's done, at the conceptual level!

[AndersNolberger]

The writing "applicaton" only have exclusive lock for writing but is alowing others to read the same file. So there is not problem since only one thread is writing to the file at a time.

Anders

[Dekard]

I'm by no means an expert, but I'll take a stab at this.

In the example you present the reading and the writing is being done by two different applications. In the actual product its being done by one app, which controls the file lock as needed and forwards the needed info to the client. Since the read\write app is one and the same there really isn't any complication.

This is in the client\server setup. In the standalone install its even easier since one app is controlling all use of the file in question.

Make sense?

[Dekard]

Originally Posted by AndersNolberger

The writing "applicaton" only have exclusive lock for writing but is alowing others to read the same file. So there is not problem since only one thread is writing to the file at a time.

Anders

So this is a view within the application where my explanation is from outside the application.

[Steerpike]

Can Sage be configured (with suitable licenses, etc) so that I can setup to record a show on 'computer 1', and then start watching that show on 'computer 2' while computer 1 is still recording it? This would be ideal for me. I have a suitably fast network to support this; I've already tested 'viewing' a (closed) MPEG file over the network, using various viewers.

I assume apps such as media player, and WinDVD, will not play the MPEG file while it's still being written because they 'assess' the total size on startup. Actually, Media Player should handle this, as it can handle streaming video ... but I guess we are also getting into the realm of program stream versus transport stream?

Thanks for your insight.

[Opus4]

Originally Posted by Steerpike

Can Sage be configured (with suitable licenses, etc) so that I can setup to record a show on 'computer 1', and then start watching that show on 'computer 2' while computer 1 is still recording it?

Yes, that's exactly what it does on the client when you are watching live TV -- it is playing what the server is recording, same as watching it on the server 'live'.

- Andy

[Dekard]

Originally Posted by Steerpike

Can Sage be configured (with suitable licenses, etc) so that I can setup to record a show on 'computer 1', and then start watching that show on 'computer 2' while computer 1 is still recording it? This would be ideal for me. I have a suitably fast network to support this; I've already tested 'viewing' a (closed) MPEG file over the network, using various viewers.

I assume apps such as media player, and WinDVD, will not play the MPEG file while it's still being written because they 'assess' the total size on startup. Actually, Media Player should handle this, as it can handle streaming video ... but I guess we are also getting into the realm of program stream versus transport stream?

Thanks for your insight.

Just to let you know, technically a 10 Mbs network could handle this. You'll get best results with a 100 Mbs network though. You wouldn't need to think about a faster network untill you looked at 10+ streams at highest quality... Sage is very low impact.

[Steerpike]

This all sounds great!

I haven't built my HTPC yet - just decided on CPU, mobo, case, etc - but I'm playing with the basic concept on an old PC that has a Hauppauge 250 card, and I'm recording/playing back on it using basic wintv2k.

When I buy the Sage software, would I need to buy Sage TV Client (to view on a 'remote' computer), plus Sage TV Media Center (to record and view on the main computer, and use stuff like program guide, etc)? <edit> or do I need the media extender?

In order to test the configuration mentioned above (record on one, play back on another computer), can I downlaod 15-day eval. versions of both products so I can play around with this configuration on 2 PCs?

Thanks!

[Opus4]

Originally Posted by Steerpike

When I buy the Sage software, would I need to buy Sage TV Client (to view on a 'remote' computer), plus Sage TV Media Center (to record and view on the main computer, and use stuff like program guide, etc)? <edit> or do I need the media extender?

You can use a server + client, or a server + (extender (MVP) or placeshifter client). For a non-portable PC, I think the Client is still better, but if you want to use an extender, the MVP extender works nicely... though I've heard they are almost impossible to find until the new version from Hauppauge starts hitting the stores.

In order to test the configuration mentioned above (record on one, play back on another computer), can I downlaod 15-day eval. versions of both products so I can play around with this configuration on 2 PCs?

Yes, SagetV & the client both have 15 day trials. I think the extender is a 7 day trial.

- Andy

[Steerpike]

15-day trial - do you happen to know, is it set from date of download, or, date of first install? I have a nasty habit of downloading stuff before I really have the time to test!

Extender ... interesting! I have an old Hauppauge Media MVP which I never put into service ... it's been a piece of shelf-ware for over a year. Seems like I can put it into service with Sage - great! Will my old version work OK? My MVP has model number 86001, Rev 03A, Lot 4803. I can't see any place to download the extender trial software ...

[Opus4]

Originally Posted by Steerpike

15-day trial - do you happen to know, is it set from date of download, or, date of first install?

The trial starts when you install the software.

Extender ... interesting! I have an old Hauppauge Media MVP which I never put into service ... it's been a piece of shelf-ware for over a year. Seems like I can put it into service with Sage - great! Will my old version work OK? My MVP has model number 86001, Rev 03A, Lot 4803. I can't see any place to download the extender trial software ...

Your MVP should work. And, there is no separate extender software -- it is built into the server installation. (I would consider trying the latest beta version. Sometimes, trials aren't available for betas, but it might be on the latest ones.)

- Andy

[Steerpike]

Awesome! Downloaded the trial, configured two machines, one ('server', one client), and it works great! I get extremely stable playback (using DVD Standard mode, 3 GB/hour) over my 802.11g wireless network! This is way better than I expected!

I'll post some 'first time impressions' as a separate post, but basically, this is an awesome program that 'works as advertised', and then some!

Thanks for all your help!

[PGPfan]

Hi Steerpike,

Glad to here things are going well for you so far! I can't add too much to what the guys have already said, except to say "Wait until you try the MVP in the mix." It really makes for an amazing system when you look at all the pieces working together.

-PGPfan

[Steerpike]

Having gotten everything else to work (and work well!), I'm now going to tackle the MVP.

Many moons ago, when I first tried the MVP, it did not support Closed Captions. Has that changed with the Sage implementation? I'm guessing not, since no software changes on the MVP itself, but I can live in hope!

Thanks!