Issue with timeshift feature

[daffy]

Timeshift is nice, timeshift is well.

 

Unfortunately, it sucks up resources like nothing... - and that has a negative impact on DVBViewer performance at large.

 

Timeshifting begins effectively recording the current channel the moment timeshifting begins. Scenario:

 

20:14: Start timeshifting

20:14: Press Pause button

20:15: Press Play button

 

Now we have this nice movie of, say, 3 hours - showing until 23:15.

 

23:14: Have a look at hard disk usage ;-)

 

After three hours of timeshifting (for a measly 60 seconds), the timeshift file has grown to (in my case) 5 GB. I fully understand *why* this is necessary in the current scheme of things (support for rewind), still, I am not too happy.

 

What I expect to happen for a timeshift of 60 seconds is a file of (60s * 7800 KBit/s - no, this is not SAT.1 :->) bytes size - and that this files only grows the moment more timeshift delay is applied. This would best be modelled by some kind of dynamically sized ring buffer and be very efficient on hard disk space.

 

Now, hard disk *space* efficiency is the most obvious thing to talk about in the presence of the current behaviour. In a different scenario, I observed video playback issues: I had a timeshift of about 45-60 minutes running on my brand-new RAID0 array (Intel ICH5R SATA onboard, so nothing fancy at all). Apparently the on-disk seek distance between recording and playback had grown so much that my picture in DVBViewer was not really smooth.

 

Solution? Perhaps a different trade-off?

 

Why not add a configuration option to switch between the current "complete recording" timeshift and ring buffer timeshift? This allows for much more space-efficient timeshifting. I understand that this will disable seeking backwards, but who uses that functionality?!

 

In order to avoid performance-inhibiting seeking on the hard disk, allow the user the choice between dynamically sized ring buffers and a statically allocated ring buffer (protection against fragmentation).

 

This is not terribly critical for me personally at the moment, but, hey, perhaps it irritates others, too. And, yes, I do think that this is an issue worth addressing :-)

[Griga]

Well, it's worth adressing, since DVBViewer Pro/GE provide a second way of timeshifting: Playing files while they are recorded. This applies to TS and MPG and will be extended to MP2 and AC3 audio files with the next DVBViewer versions resp. DVBViewer Filter version.

 

So the first method - the so-called timeshift - could be changed in the aforesaid way, even without a ring buffer yes/no option. Starting a normal recording delivers the whole file, and still provides timeshift.

 

However, in a ring buffer the write pointer must *never* catch up with the read pointer (from behind, of course), otherwise big trouble - that's clear. Unfortunately it's pretty difficult to estimate how much disk space is required for x minutes, since most TV broadcasters use a variable bit rate for video. In may vary within a wide range.

 

Let's assume, the user clicks Pause, and disk-writing starts. After a minute the user starts playback. The DVBViewer writes one more minute to the end of the file (as safety margin) and then continues at the beginning. But now a broadcast with a siginificant higher bitrate (like a sports event) starts, so that writing becomes faster than reading, at least for some time... there you are. Not so easy.

[ziadost]

"DVBViewer Pro/GE provide a second way of timeshifting: Playing files while they are recorded. This applies to TS and MPG and will be extended to MP2 and AC3 audio files with the next DVBViewer versions resp. DVBViewer Filter version."

 

how do i do this? i would like to be able to do a normal rcord and watch at rewind/forward while i am recording. the only way i can currently do this is if i timeshift at the same time, and that takes up twice the space and resources.

[Guest Oliver]

Just open the file being recorded.

 

Bye

[ziadost]

but i have to keep DVBViewer running, don't I? i dont' want to run 2 videos at the same time. is there any way to disable a/v rendering? i am using 3.0 (3.1 doesn't work on my system for some reason). also, is there any way to manually put the program in slumbermode?

[Griga]

i am using 3.0

 

For playing a file while it s recorded you need DVBViewer Pro 3.1 or DVBViewer GE.

 

is there any way to disable a/v rendering?

 

Rather poor in DVBViewer 3.0. A bit better in DVBViewer Pro 3.1. DVBViewer GE provides the best disable a/v capabilities. See here.

 

also, is there any way to manually put the program in slumbermode?

 

Yes. Create a DVBViewer shortcut on your desktop, open the properties and append the commandline parameter -c in the target input line.

[ziadost]

thanks griga, i will try again

[ziadost]

also, everytime i tune/switch to any channel, DVBViewer displays a black screen and an icon 'paused' in the top-right corner. i tried clicking the timeshift button, but still nothing. the only way i can make it display the channel is i have to right-click the window, and then click the timeshift button to disable timeshift. in other words, DVBViewer enables timeshift EVERY time i tune a channel. 'automatic timeshift' is off.

 

it gets really annoying. any way to stop it?

Edited May 24, 2005 by ziadost

[Guest Lars_MQ]

it gets really annoying. any way to stop it?

Yeah, check your userdata you received on purchasing the DVBViewer Pro and make sure they are entered correctly.

[ziadost]

do you mean my username/password that i used for installation?

[Guest Lars_MQ]

Well, you have received a email from hackbart on purchasing the DVBViewer Pro with this data, don't you?

[ziadost]

i don't have the data you mentioned, as this version of DVBViewer is actually my cousin's. i just asked him about it and he does not seem to have it.

 

what exactly is it? a series of commands, etc. maybe he can find it, cause he wont let me go through his mail

Edited May 24, 2005 by ziadost

[Guest Lars_MQ]

Well a pirated version won't work, don't bother about "finding" the data.

[ziadost]

it is NOT a pirated version. by your logic, your family is not allowed to use your version of windows because it is not under their name.

 

please do not make such assumptions. he may have trouble finding it since his only email account is a crappy 2mb (supposed to be 250mb damn you hotmail) hotmail account

 

we should be able find that email soon. thanks for your help

Edited May 24, 2005 by ziadost

[Guest Lars_MQ]

i don't have the data you mentioned, as this version of DVBViewer is actually my cousin's. i just asked him about it and he does not seem to have it.

Well, if he bought it, he must have this data.

He can always send a email to hackbart with his purchase details and he will receive the data again.

by your logic, your family is not allowed to use your version of windows because it is not under their name.

No, actually, if he uses the software, you are not allowed to use it. You're also not allowed to "share" the windows version. Have you ever read the license agreement of windows?

But maybe microsoft will be interessted about your point of view of "family" versions

 

And another point. you have the software running. You can only download it from the membersarea. You need your userdata to get into the membersarea. you can only install it with entering the userdata. I wonder where you got the installer and the data from if your cousin hasn't got the userdata.

Come on, stop bullshitting me.

 

it gets really annoying. any way to stop it?

You asked for a solution. I gave you the reason for this behavior and the solution.

 

Come back if you have valid userdata.

[Griga]

@ziadost: First you've stolen DVBViewer, and then my time. You won't get support anymore unless I can be *absolutely* sure that you've bought DVBViewer Pro.

[Mr. Bun]

Back to the original topic:

 

Well, it's worth adressing, since DVBViewer Pro/GE provide a second way of timeshifting: Playing files while they are recorded. This applies to TS and MPG and will be extended to MP2 and AC3 audio files with the next DVBViewer versions resp. DVBViewer Filter version.

 

So the first method - the so-called timeshift - could be changed in the aforesaid way, even without a ring buffer yes/no option. Starting a normal recording delivers the whole file, and still provides timeshift.

 

However, in a ring buffer the write pointer must *never* catch up with the read pointer (from behind, of course), otherwise big trouble - that's clear. Unfortunately it's pretty difficult to estimate how much disk space is required for x minutes, since most TV broadcasters use a variable bit rate for video. In may vary within a wide range.

 

Let's assume, the user clicks Pause, and disk-writing starts. After a minute the user starts playback. The DVBViewer writes one more minute to the end of the file (as safety margin) and then continues at the beginning. But now a broadcast with a siginificant higher bitrate (like a sports event) starts,  so that writing becomes faster than reading, at least for some time... there you are.    Not so easy.

<{POST_SNAPBACK}>

 

Isn't there another way to achieve low-disc-usage timeshift while avoiding the hazards of a ring buffer?

 

If DVBViewer were to automatically split the timeshift-file every 60 seconds (or so) into incrementally numbered chunks DVBViewer could then delete a chunk of the timeshift-file once it has been replayed (i.e. watched), thereby limiting disc-usage to the space you need for the timeshift-delay plus 2 minutes (at worst).

 

That would, of course, require DVBViewer to be able to automatically and seamlessly play split files as a whole. Which would be a nice feature to have anyway and should, IMHO, not be too difficult to implement. (But what do I know?)

 

One could even allow for some limited (x minutes) backward-seeking by deleting the (n)th-chunk only after the (n+x)th chunk has been replayed.

 

Greetz,

Mr Bun