Huge quality drop when timeshifting or recording

[Niels Hansen]

Hello,

 

I have a Pinnacle PCTV 200e USB DVB-T tuner. When I view a stream (Danish public-service free to air TV) without using the timeshift or recording functions, the quality is prefect, no dropouts in either video or audio. But, as soon as I start timeshifting or recording it looks like large parts of the stream are lost, resulting in massive frameskipping and sometimes also audio drop-outs, both in the live playback as well as the recorded content.

 

I haven't yet tested recording without simultaneous live playback. I am using version 3.5.0.

 

Using other software, I have experienced slight dropouts constantly, even when not recording, but the dropouts in the recorded streams weren't as bad either, which leads me to believe this is a software problem.

 

OS: Windows XP Pro SP2

CPU: Dual Opteron 248 (2.2 GHz)

RAM: 2.48 GB

Tuner: Pinnacle PCTV 200e attached to High-Speed USB 2.0

Software:

DVBViewer 3.5.0

Tried two different MPEG2 decoders: Gabest MPVDecoder and DScaler 5 MPEG2 decoder 0.0.0.8

Audio decoder: ffdshow audio

Tried both Overlay and VMR7 renderers

Using the (to my knowledge) latest drivers for the tuner

support.zip

Edited November 9, 2006 by Niels Hansen

[Guest Lars_MQ]

Well you excatly tried the worst decoders. try cyberlink. Most likely a system and/or reception problems.

[Niels Hansen]

I believe it's not a decoder problem, because the TS file resulting from recording is in fact corrupted. Playable, but missing lots of frames and many frames have massive block-outs. Also, CPU usage during regular viewing (not recording at the same time) rarely reaches even 25%, and the I/O subsystem shouldn't have trouble coping with the amounts of data (about 4-7 Mbit/s per channel).

Edited November 9, 2006 by Niels Hansen

[Guest Lars_MQ]

No the decoder has nothing to do with the recording. this is independent. But ifyou use a not so good decoder for livetv and the same for watching a recording, it may be of importance. The cyberlink is a comonly confirmed good decoder, so if you use this we can nearly sure exclude decoderproblems.

 

What kind of antenna do you use? the fact, that other programms also have problems indicates a reception issue.

DVB-t is no wonderTV as promised everywhere. In fact if you have a bad reception, it works far worse than an analog TV receiver on the same antenna.

[Niels Hansen]

I just tested the CyberLink decoder from PowerDVD 7, and it results in the same problems. (In fact it seems to have worse video/audio sync than the other two decoders.)

 

For antenna I have a roof antenna with amplifier. As I also explained before, if I do not record or use timeshift functions, but only view TV live, there are no dropouts or other visible/audible corruptions at all, ie. "perfect" reception.

As soon as I press the Record button, the video and audio in DVBViewer starts skipping and stuttering, no matter which of the decoders or renderers I use.

 

I also tested recording with live display turned off, ie. start recording, then View -> Close Graph. The resulting TS file was still corrupt all the way through.

[Klaus_1250]

What kind of setup do you have as to your harddisk? (model, IDE/SATA, DMA On, etc). How are its SMART-attributes? Have a heavy virusscanner? From what you describe, the issue seems to occure whenever redirecting data to the HD, so it might be fruitfull to investigate there.

 

I have a totally different setup, but absolutely no problems with Timeshift or recording.

[Niels Hansen]

Yes, I just discovered that. If I have anything doing heavy disk access the video starts to lag. (This usually doesn't happen in other applications.)

 

In fact, the problem might be my motherboard. The harddisk I use for recording/timeshifting is a WD SATA disk. (It's the only disk with enough free space.) Now, the thing is, my motherboard has neither SATA nor USB 2 on-chip, meaning both go over the PCI bus, so it might be some bandwidth congestion there. I'm trying to defragment the disk in the hope it'll solve the problems, but in the end a motherboard replacement might be the only solution.

 

And no, I'm not running any software that monitors file accesses, such as virus scanners or "personal firewalls".

I'll try to make space for recording to a different disk though, one on either the on-chip PATA controller, or my PCI PATA RAID controller.

 

(Maybe this thread should be moved to a general support forum instead?)

[Klaus_1250]

Do the PCI USB2 and PCI SATA card share the same IRQ? PCI bus bandwidth shouldn't be a problem.

Edited November 9, 2006 by Klaus_1250

[Niels Hansen]

Hmm yes, indeed they do share IRQ. I'll look into a way of changing that and report back if I'm successful.

[Klaus_1250]

OK, could or could not be a problem. You might also try to see if recording just the program stream (.ps) makes a difference and if both cards support bus-mastering.

Edited November 9, 2006 by Klaus_1250

[Niels Hansen]

I think it's confirmed it's the IRQ problem, I tried recording a short clip onto another disk on a controller with a different IRQ, and there were no problems whatsoever.

Unfortunately, neither Windows nor the BIOS setup offer any way of changing those IRQ assignments (apparently by design, see this) so there's no real solution. Maybe set up a separate machine to act as "TV server"...

 

Thank you very much for your help and time, and sorry for blaming it on the software first