PCR Check taking too long

Begonnen von jaydear, Oktober 16, 2017, 23:41:56

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jaydear

I'm using v2.0.96 and it is taking over 3 minutes to scan a 16GB recording consisting of 4 x 4GB files. I only need to know whether there's a PCR problem, not always the details, so a quick scan is good enough for me most of the time.

I've un-checked "Enhanced PCR Check active" and selected "Ask is needed" in "Timer Correction (patch to start with 0)", but it's still doing a full scan. How do I stop it please?
The.Doctor is the ants' pants :)

Cypheros

How long is the duration of the recording?

Scanning speed is depending on the source media drive. Is it a network drive, maybe?

jaydear

It's a USB3.0 drive plugged into the PC and the recording length is about 7.5 hours of MPEG2 TS. With a normal recording of the same length it takes about 20 seconds all up, but if there's a PCR problem it does a full scan which takes over 3 minutes. The irony is that the PCR problem is usually in a 4GB segment I don't need anyway.

The.Doctor is the ants' pants :)

Cypheros

Sorry, TS-Doctor doesn't know what part of the recording you need and what not. PCR problems are often the cause of many errors.

jaydear

OK, you are correct, I agree. Sorry to be a nuisance, but there are a few different things TSD does when it encounters PCR errors.

Usually I have no PCR problem, probably because I have good DVB-T reception, but I've occasionally seen (minor?) PCR errors found by the normal quick TSD scan: The green pulse symbol that appears in the PCR check icon with no further action required, the 'wrap-around' error that asks if it should be patched, and one that reports that there are PCR errors and asks if it should make a new corrected file. Then there is the really s-l-o-w one I've just encountered that causes TSD to scan the entire file in fine detail (I assume).

Just my opinion, but I think it'd be good if TSD asked before starting a scan that will take so long, e.g. "Major PCR errors. Scan and repair the whole file? Yes/No", or at least be able to stop it elegantly, perhaps with the Escape key. Or maybe just have a red pulse symbol in the PCR check icon as a 'major' warning?

If a USB3.0 connected 1TB hard drive takes 3 minutes for a 16GB file (4x4GB), I hate to think how long it would take over a Gigabit network connection, let alone 10/100MB/s or WiFi.
The.Doctor is the ants' pants :)

jaydear

#5
Update... I've just had it happen again - it is "Finding PCR switch position" that is taking 3 minutes on a few recordings so far. Usually this part of the scan only ever took a couple of seconds, even if there was a wraparound fault.

Is it this version of TSD that has changed or is it a new PCR fault in some recordings?
The.Doctor is the ants' pants :)

Cypheros

I don't know that they are doing in the broadcast center but the source of the PCR problems are over there:

Strange PCR Jump: 21:17:50.437 [05:03:25.999] -> 00:00:26.141 [10:16:45.421]
                  51598267  -> 52430506
Strange PCR Jump: 00:20:58.523 [10:37:17.803] -> 00:01:29.302 [10:17:48.582]
                  56591698  -> 57423947


Wraps are easier to handle because the timers overflow and restart at zero (+- some seconds). This can easily be corrected but a random jump needs a detailed scan of the larger area, because you don't know at which point the timers jump and to what value.

jaydear

#7
Thanks, understood.

Unfortunately, I just had another file with PCR jumps and the fixed file still has the same problem  ???
The.Doctor is the ants' pants :)

ErichV

Zitat von: jaydear am Oktober 23, 2017, 18:45:29
Unfortunately, I just had another file with PCR jumps and the fixed file still has the same problem  ???

In such cases you have to repeat the stream fixing process as long as a PCR jump isn't detected by TS-Doctor anymore.
1 x Humax ESD-160S, 1x TechniSat TechniBox S4, 2x TechniSat Skystar USB 2 HD CI, Nvidia Shield TV Media Streaming Player, TS Doctor 4.0.37, DVBViewer Pro 7.2.5.0 mit DVBViewer Media Server 3.2.5.0

Cypheros

Yes, TS-Doctor only fixes one jump at a time. Just compare the logs to find out if the number of "strange jumps" decreases after fixing several times.

jaydear

Ohhh, OK, I didn't realise that.  ::)
The.Doctor is the ants' pants :)


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