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TS recording recording problem


Roy Brooker

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Roy Brooker

We have DVBViewer version 5.0.0.0 working with a PCTV USB DVB-T2 tuner and a high spec HP laptop. We want to use the system to capture complete transport streams (.ts files) from the DVB-T2 service in the UK.

 

We are able to capture a streams but there are a couple of problem. Firstly we found we can only capture the complete TS if the recording is done via the "timer function" and select "transponder dump". (we have selected .ts as the required file format in the options menu).

 

The main problem is more serious: when playing back the streams, via a Dektec T2 modulator, the sound is either randomly out of synch with the picture or it breaks up. Searching your web forums we found references to a "Video Recorder plug in" which suggested it tackled both these problems, but we cannot find this plug in to download it. The details of this plug in suggested that it has more customisable options and that the sound breakup problem may be due to PCR (clock reference) issues which seems plausible.

 

Support.zip file attached as required support.zip

 

Any ideas

 

 

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Firstly we found we can only capture the complete TS if the recording is done via the "timer function" and select "transponder dump".

An alternative is using the TransEdit Analyzer -> right-click the PID List -> Select All -> click Start Recording. Download TransEdit from the members area, read the ReadMe and more in the TransEdit Manual.

 

The Videorecorder Plugin is outdated and not available anymore. It wouldn't help anyway in your case, as far as I can see.

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First: Check with the transedit analyzer, if there are all expected channels/streams present and if there are disconties reported in the TS-Dump.

If all channels/Stream are present and no disconties are reported, please check you playback chain for problems.

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Roy Brooker

Dear Griga and Lars: Thanks for the suggestion to use TranEdit that has solved the problem of being able to do an instant record and gives us a lot more information to work on. However it has not solved the variable audio synch problem but it has given us a few clues:

 

  • Recording and playing back DVB-T standard definition) streams works fine. The problem only occurs with recording from a DVB-T2 service.
  • Our playback chain is a Dektec DTU-215 (modulator designed for DVB-T2) which works perfectly when fed with DVB-T2 transport stream test files supplied to us by the broadcaster (BBC), it only has problems from our recorded files.
  • The recorded T2 transport streams do playback correctly using the media player on the laptop.
  • TransEdit analyser does not report any problems with the recorded files but we do notice that the reported “Signal Quality” (bottom right of screen) is only around 40% when recording DVB-T2 but it is 100% when recording DVB-T. This is very strange because all signals are from the same transmitter and at the same power level.

 

So at the moment our suspicions are with the quality of the signal being received by DVBViewer rather than the playback chain. Our receiver is a PCTV USB device with the latest drivers.

I intend to carry out some tests using a different transmitter site where we can guarantee a better quality signal to see if that solves it. I will keep you posted.

 

In the meantime thanks for your help

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(Off-topic post by jhrdlicka moved to the Recording Service section - the next completely-out-of-place-post will just be deleted :mad: )

 

but we do notice that the reported “Signal Quality” (bottom right of screen) is only around 40% when recording DVB-T2 but it is 100% when recording DVB-T.

 

Don't rely on signal quality / strength reported by DVB device drivers. Mostly the values are only rough indicators, if at all. If there was a problem with the signal quality, you would see it in TransEdit as "Missing Packets" and/or corrupted streams with random PIDs appearing in the PID list..

 

Our playback chain is a Dektec DTU-215 (modulator designed for DVB-T2

 

What else? A modulator creates a modulated signal, but doesn't play anything.

 

the sound is either randomly out of synch with the picture or it breaks up.

 

I would rather assume that under certain circumstances your modulator plus whatever can't cope with the LOAS/LATM packaged variable bitrate AAC audio that is used in British DVB-T2 broadcasts. Do you have some space to upload a BBC test file and a recorded sample? Then I can have a look at it.

 

BTW: Does the TS delivered by your DVB device include null packets with PID 0x1FFF? Some devices drop them in order to save bandwidth, thus delivering an incomplete TS.

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