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StephaneM

Unusual audio issue on DVB-T (France)

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StephaneM

Hi All,

 

In France we are in the process of giving back some DVB-T frequencies to 4G phone network and as such yesterday in the whole country all DVB-T transponders were changed to pack more channels in a transponder and also all channels are now in MPEG4 / E-AC3 (before that some MPEG2 channels still existed).

 

Since then I noticed some strange high pitched noise from time to time an all DVB-T channels : on two different computers, with two different DVB-T devices, with two different antennas (both directed toward the same emitter though, both are brand new as well as the cables), these high pitched noises are happening at the exact same time.

 

When this happen DVBViewer (DVBSource) doesn't see any discontinuities in the signal, and the video doesn't have any artifact whatsoever.

 

Have you any idea of what may be causing this? Or any idea on how troubleshoot this issue?

 

I'm really puzzled, is this an error correcting going wrong, is this an audio codec issue...

 

Best Regards,

Stéphane

 

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Griga

Can you record such a piece of audio (best as TS) and upload it somewhere?

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StephaneM

Can you record such a piece of audio (best as TS) and upload it somewhere?

 

Ok, I'll do in a few minutes and post back the link for the sample (and as to where the glitch is happening).

 

I also made some test, and it seems to me that it is most probably related to the audio decoder : both FFdshow and LAVAudio are hissing, whereas the MS DTV decoder doesn't quack at all (within DVBViewer itself only changing the codec)

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StephaneM

Ok here is the link of a video sample with the audio glitch (recorded by DVBViewer).

 

The audio glitch occurs near the end about 00:01:16 (there is only one audio stream)

 

If you playback with ffdshow you'll hear the glitch (you can somehow have it filtered with FIR) and you'll not hear it with the Microsoft DTV-DVD Audio Decoder (at least on Windows 10)

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Griga

Confirmed. It happens with all freeware decoders: AC3 Filter, LAV, ffdshow. With VLC as well.

 

I've informed the LAV developer about the issue. Maybe he can find out more...

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StephaneM

Well at least it's not hardware related so I'm releaved. Time to find an audio decoder that can decode those audio streams properly. I'm guessing FFmpeg devs will soon adress this issue now that all french DVB-T channels are concerned (before it was only six channels that were exposing this).

 

Tanks for looking into this.

 

Regards,

Stéphane

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nuts

Microsoft Decoder should work (follow the link posted by Griga ;) ).

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Griga

Already known and posted by StephaneM above :rolleyes:

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StephaneM

Microsoft Decoder should work (follow the link posted by Griga ;) ).

 

Yes the Win 10 version is working width DirectShow players, on Win 7 it is not however (no sound). So that's why I'm searching something else (I also want something that can expand stereo with DBPL II)

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Griga
on Win 7 it is not however (no sound).

 

Due to licence restrictions. AC3 only works in MS software.

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StephaneM

Despite having tested all software I had purchased over the years (PowerDVD, Arcsoft TotalMedia Theater, Win DVD) I was unable to make any of these codecs works with DVBViewer for decoding the EAC3 properly. It's really a shame.

 

So in the end I upgraded this Win7 PC to Win10 and can make use of the basic MS decoder :D

 

If anyone knows a trics to make WinDVD 11 (because it's the one I currently use for BluRay playback on this machine) codecs works in DVBViewer let me know (the WinDVD does have a nice dolby PLII upmixing)

 

Regards,

Stéphane.

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