Problems recording Lost on C4 Freeview in the UK

[neilraymond]

Hi

Just wondering if anyone had problems recording the last 2 episodes of Lost on C4 in the UK last week. They were broadcast on wednesday and sunday and I saw the same problem both times (4 recordings in total).

Looking in the logs it looked like recording was successful, and the start and end log entries appear at the correct times, but when I actually tried to watch any of the recordings each one was only about 10 minutes long. All slightly different, but all between 10 and 11 minutes. The files were about 200MB, which is what I'd expect for a 10 min recording.

I opened the recordings in windows media player and it shows that they were the correct length, but when it got about 10 minutes in it stopped playing, although I think the sound continued.

I processed the files with videoredoplus's quickstreamfix function and then re-opened them in windows media player, and the length was now showing as the actual length of the recording e.g. about 10 minutes.

Has anyone else seen anything like this, or got any ideas as to why it might be happening? I've never seen this behaviour before or since and I've done a number of recordings since then to try and reproduce it.

I've got an AOpen i915GMm-HSF mboard with a Pentium M 740, and a Nova-T 909 capture card.

Please help me avoid getting lynched by my other half :mad:

Cheers

Neil

[djtaylor]

As I iron out the bugs including what I think is an underrated PSU for the 6 hard disk based machine i'm running, one of my other things I need to change is the aerial feed.

I won't bore you with detail but I have had corrupt recordings where recordings have ended short or that the time appears correct but there are simply so many frames missing or corrupt that even running them through videoredo just doesn't help. It fixes the stream corruption but can't fix the general lack of data.

I have done a few tests here that confirm that it's a lack of signal although only just, maybe you have a similar problem? Are you feeding the TV card direct off the aerial with no other feeds going elsewhere?

I had no problems recording either of the final episodes on Sunday, in fact I chose to record both finale's on Sunday because my recording on Wednesday crapped out.

David.

[PhilW]

I too missed those episodes ! With exactly the same outcomes (ie video files 10 mins in duration or missing video after 10-15 mins into the recording, with audio OK).

My antenna goes through a mains powered signal amp, and then to two tvs.

Is this a signal problem ? How can I find out the signal strength available ?

[neilraymond]

Interesting to hear that someone else has had exactly the same problem as me. What capture cards are you guys running?

In terms or aerial I've got a similar setup to PhilW, with the aerial feeding an amp which then feeds the TV and the DVB card. I've suspected for a while that there's a problem with the signal or there's interference being picked by the leads somewhere. The cable is pretty old, and I don't imagine it was the best quality stuff in the first place.

The annoying thing is that the TV picture is almost always perfect and the TV shows good signal strength, but it seems that the DVB card can't cope with any temporary dropout in the signal when it happens. I don't know if it's a hardware thing or a driver thing, but I can't imagine that commercially available freeview PVRs suffer from the same problems or the companies making them would probably go bust. Shame these things can't be made more resiliant of temporary signal faults. Guess I'd better get to work replacing the aerial cables etc.

As I said in my original post, I haven't been able to reproduce it so far, but the odds are it'll happen tonight as Touching the Void is on again and that's failed to record properly about 3 times so far (although with different symptoms)! :confused:

Neil

[djtaylor]

Well ok then just so you can compare, I have a Freecom stick and a Nova-T PCI.

I have a less than optimum aerial on a long run down and round the house to a TV. That was supposed to be the only one that I was running off that aerial, the cable is CT100 so that's better than typical "low loss" TV downlead.

However, then the PVR project started so that gets split and then onwards via another fairly lengthy run to my office where of course, it's split again to the two TV cards. I tried running the Freecom from the output of the Nova-T but there wasn't enough signal to drive the Freecom at all.

At present, there's a plug in amp to feed both but this is about the worst way of doing it possible. Amps should be at the head end to overcome distribution loss, not at the final destination where they amplify interference!

I'm 29 miles from the transmitter so my plan is to have a very high gain antenna such as the Televes DAT75, very close to the PVR so short downleads and use a suitable device such as the MRD to split the signal at the right place.

The biggest effect that I noticed was when playing live TV to an MVP, there was loads of blocking and break up but when I simplified the signal path as a test, this went away. That's as good an indication of poor signal as I need, when playing back on the PC it's not as bad but I think that shows that the MVP isn't too happy with a corrupt stream being sent to it.

[neilraymond]

Ha. It did happen again with Touching the Void. Does anyone know if there's a way to set logging or something on either the drivers or the mux (I'm currently using showshifter) to try and work out where the errors are coming from?

[sub]

Try the DVR-MS mux. It seems the most resilient to gliches, or changes in timestamp continuity.

[neilraymond]

Ok, will give it a try. I tried it in the past and stopped using it, although I can't remember why. Guess I'll find out soon enought if it was a good reason...

cheers

Neil

[djtaylor]

If using the MS-DVR mux, doesn't that then require a realtime transcode to play out to MVP's? Or is it a fairly easy process from the MS-DVR process compared with say transcoding divx encoded?

David.

[sub]

Thats correct. DVR-MS is a bit of pain if you intend to use it with an MVP, but it does depend on how you use things. If you generally just do recordings (ie, not watch live tv), then you can set the post processing to automatically convert from dvr-ms to .mpg when the recording completes. This only taks a minute or two to process after each recording, since its just really remuxing the recording.

If you're not using an MVP, then DVR-MS is pretty good choice.