Virgin Media Community

[Mattg68]

Dolby digital set to always convert but no sound from centre speaker unless true 5.1. Suggests the conversion from stereo to Dolby surround isn't working. I can manually set the amp to surround but this shouldn't be necessary. Any suggestions other than changing the surround mode on the amp each time ?

[Roger_Gooner]

I think you need Dolby Digital and "Follow Content" which, if my understanding is correct, will effectively bitstream the audio so that Dolby Digital 5.1 and 2-channel PCM will be passed through to the AV receiver/amp.

[Zach_R]

Hi @Mattg68,

Thank you for your post and welcome back to our community forums. We're here to help.
 

I am sorry to hear you've been having a bit of trouble with your audio recently. Have you followed the advice provided by @Roger_Gooner yet? If so, have they helped at all?

Thanks,
 

[Mattg68]

Hi Zach,

Yes, if I set it to Follow content then the output is 2.1 and I can convert to Dolby surround on the amp. 

But surely setting to always convert should output in surround 5.1 from the source.

The amp shows the output as Dolby digital plus but no sound from the centre speaker unless I set the amp to convert to Dolby surround.

This suggests to me that the conversion is not working properly.

[Roger_Gooner]

Dolby Digital does not mean that you always get 5.1 as some are broadcast in stereo, and some HD channels such as ITV HD and E4 HD are also broadcast in stereo. Incidentally I don't see why you'd want to convert stereo to surround sound as I think it's best to hear what is broadcast.

[Mattg68]

Hi Roger,

Thanks for the reply. I'm certainly no expert but my understanding was Dolby digital gives 5 channels

https://whatis.techtarget.com/definition/Dolby-Digital

The amp info for the input/output would also seem to support this as it shows 5 channels from the virgin box.

If I set the Virgin output to Follow Content and let the amp convert to Dolby surround I get sound from the centre speaker. 

Maybe the conversion performed by the virgin box doesn't work in the same way.

Recently the sound quality seems impaired and I wondered if there'd been a recent firmware update that might be the cause.

Its not a major issue other than I have to manually select the surround mode on the amp depending on the source output.

[Roger_Gooner]

Dolby Digital has the capability of providing five channels but is not required to do so, indeed it be entirely wrong for DD to produce fake 5.1 from stereo input. There's no shortage of stereo from DD, look no further than BBC1 HD, BBC 2 HD and Sky Witness HD.

[Mattg68]

I'm not sure what Virgin are trying to achieve then.

These are the input/outputs from the AV amp with each setting.

 

 

 

 

[SpookyElectric1]

Since the weekend I too have lost centre speaker sound on some TV channels (notably C4) using any Dolby setting except ‘Disable’. Nothing has changed on the Amp.

[Roger_Gooner]

---

@Mattg68 wrote:

I'm not sure what Virgin are trying to achieve then.

These are the input/outputs from the AV amp with each setting.

 

---

This looks right. Always Convert outputs 5.1 (a better test is BBC 1 HD which is DD stereo) and Follow Content outputs 2.1 from PCM 2.0 stereo.