Losing chunk of audio in middle of file

tobyW

Member
I just ran a movie through QSF in TVSuite6 beta 836a:
Qsf reported 247750 PTS underflows; Max PTS underflow (ms) 336648.00,
and it lost a chunk of audio in the middle of the file.

Tried it again with TVSuite beta 835b:
Qsf reported simply Max PTS underflow (ms): 5620.00,
and on a quick scan the audio seemed OK .

Is there maybe a setting I need to change for 836a?
 

Dan203

Ex-Senior Developer
Setting the TS muxrate higher will eliminate the underflows. TS files stored on disk don’t actually care what the muxrate is, it only matters to broadcasters. So set it to something high, like 50 or 100 and that'll eliminate the underflows.

Not sure if that'll fix the audio issue though. Give it a try and let me know. If it doesn’t then we'll troubleshoot it further.
 

tobyW

Member
Hi Dan203.
Yes, a higher muxrate eliminated the underflows, and thereby fixed the audio issue.

Thanks for that, and thanks also for your various elucidations on this subject,
such as in the following thread started 7 years ago by lamnesik:
https://videoredo.net/msgBoard/index.php?threads/settings-output-mux-rate.35251/

I suppose the question remains, did something change between 835b and 836a to trip me up,
as I can't see any difference in the Transport Stream output profile settings?

Thanks again,
tobyW
 

Dan203

Ex-Senior Developer
Hi Dan203.
Yes, a higher muxrate eliminated the underflows, and thereby fixed the audio issue.

Thanks for that, and thanks also for your various elucidations on this subject,
such as in the following thread started 7 years ago by lamnesik:
https://videoredo.net/msgBoard/index.php?threads/settings-output-mux-rate.35251/

I suppose the question remains, did something change between 835b and 836a to trip me up,
as I can't see any difference in the Transport Stream output profile settings?

Thanks again,
tobyW
There was a change to the default muxrate in the most recent beta, so if you're seeing a difference that's probably why. This change was made for a Pro customer where the muxrate is much more important.

If you run into this a lot just go to Tools->Manage Output Profiles, edit the TS profile and change the muxrate to a higher value That will permanently change it so that you don’t have to remember to increase it every time.
 

virbing

Member
fwiw, I am seeing the same issue. I haven't had time to visit the forum or troubleshoot - wish I would have know sooner since this has been happening with a number of my recordings. I think you might want to change the default muxrate back since it might be difficult to determine how many people are running into this issue without realizing why.
 

Dan203

Ex-Senior Developer
Hi, my TS mux rate is set to ATSC -19.2Mbps. So what does that mean?
If you're having the same issue try bumping it up. For local files that you're going to use for personal use it doesn't really matter what the muxrate is. Muxrate only really matters to broadcasters.
 

Winnewup

Member
Hello,
since the last beta, muxrate set to auto on ts-files works much better than before. Have you tried out this? If stored on local disk, you don't have to choose ATSC. And yes, high pts underflows can cause audio playback issues (depends on player).
But I am wondering about that high pts underflows. I am using VRD almost only with ts-files. And if I get that high pts underflows, I nearly almost find issues in the source file (see log file: set diagnostic option to middle). Sometimes there is a frames issue near the beginning of pts underflows. If so, just cut out one frame so that VRD recodes some frames. This might help if the ts-file is a bit "stubborn".

Regards
Frank
 

tobyW

Member
Hello,
since the last beta, muxrate set to auto on ts-files works much better...
Regards
Frank
Thanks Frank,
Fwiw, I did some comparative tests of muxrate settings on my problem file and others,
using the current TVSuite6 Beta 836a.

The following settings
ATSC mode 19.2Mbs, Auto at 8 or 32 samples, Manual at 5Mbs or less
all failed to solve the problem, but settings of
Manual at 10 or 20 or 30Mbs
all worked OK.

So I settled on choosing Manual and accepting the default 10Mbs, and since then
all my QSF's using that TS profile have been clear of PTS underflows. (So far!)

I suspect there is more discussion yet to be contributed to this subject. Anybody?
TobyW
 

Winnewup

Member
Hello Toby,
the setting with the lower manual bitrate sounds very unusual... Normally the manual bit rate has to be set higher if it doesn't work on auto and if there is no error in the file.
Maybe Dan is interested in taking a look at the problematic file?

Regards
Frank
 

tobyW

Member
HI Frank, yes it's a bit of a mystery to me. Unfortunately I've deleted that file due to disk space, but glitches are common in my free-to-air files.
Anyway the mux rate dialog initializes to 10Mbs, experience has taught me to favour VRD defaults, and my problem seems to have gone away.
Regards
TobyW
 
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