no centre sound from my surround audio system for 5.1 audio

[KaiTa]

I have got new sky puck, and tried auto/PCM/pass-through in the setting. I have used a 5.1 audio extractor to get audio through optical cable and connected it to Sony DAV-DZ810W home theater system. There is no sound but static noise from centre speaker when watching 5.1 audio netflex movie. The sound system is set to multi-channel. But if set to Dolby Digital or other modes, I can hear centre sound. I am not sure which one is faulty. the sound system , the extractor or the sky puck. has anyone have this issue?  

[CoffeeDrinker · Accepted solution]

@KaiTa  The Passthrough setting will attempt to pass an undecoded Dolby Digital Plus signal out from the Puck via HDMI. Your Sony system cannot understand DD+ but does support Dolby Digital (the 5,.1 sound format from the 90s). Despite there 'only' being the 'Plus' change in the name, Dolby Digital Plus and Dolby Digital are very much different sound formats.,

If you set your Puck to output Dolby Digital (not DD+) via HDMI, this will ensure that your Sony system is getting a sound format it can understand. As long as your audio extractor is working properly, it should extract the Dolby Digital 5.1 sound from the HDMI and output it via the optical/SP-DIF connection to your SOny unit. As long you have the Sony set to AFD Multi, it should  decode the incoming 5.1 signal; and reproduce it properly through your 5.1 speakers ( page 55 of the Sony manual at https://www.sony.com/electronics/support/res/manuals/4165/41654861M.pdf )

The manual does mention that your Sony device supports ARC (audio return channel) on it's HDMI connection. If your TV also supports ARV on one of its HDMI ports, connect the Sony device to this port via a HDMI cable, connect the Sky Stream puck directly to the TV and ensure your select TV as the source on the Sony box. The Dolby Digital sound should then flow from the Sky Stream puck, through your TV and then into the Sony box for decoding and amplification.

Let us know how you get on.

[KaiTa]

Thanks! It works with DD. I assumed DD generates a virtual 5.1 audio. So PCM stereo just outputs 2 channel audio instead of 5 channel in audio stream? Why doesn't the puck outputs PCM 5.1 audio?

[CoffeeDrinker]

PCM stereo, at CD quality, takes around 1.5 megabits per second (1.5 Mb/s) of datarate/bandwidth. PCM stereo fed into a 5.1 processor will apply some form of processing, usually some form of Dolby Pro-Logic/Dolby Surround, to spread the two channel stereo around the 5.1 channels, making sure that dialogue still comes out of the centre channel (I'm simplifying massively).

PCM 5.1 would take around 5 to 6 Mb/s. By comparison Dolby Digital and Dolby Digital Plus are designed to carry 5.1/7.1/Atmos sound between 384 to 640 kilobits per second, around a third or less than even PCM stereo.

The PCM Stereo output of a Sky Stream puck is the Dolby Digital Plus compressed data from Sky, downmixed to a 2.0 format then outputted as uncompressed stereo - this is offered as just about any TV or sound system ever made will support PCM stereo as an absolute minimum. If PCM stereo doesn't;t work then nothing will.

Dolby Digital Plus can carry 1.0 (mono), 2.0 (stereo), 4.0 (quad), 5.0, 5.1, 7.1 and Atmos.

Dolby Digital can carry 1.0 (mono), 2.0 (stereo), 4.0 (quad), 5.0, 5.1, with anything less than 5.1 decoded and upmixed by your sound system to 5.1.

PCM Stereo can carry 1.0 (mono), 2.0 (stereo) and the older Dolby Surround matrixed stereo format (don't ask!)

With your puck now set to output Dolby Digital, 5.1 will come through as 5.1 and older stereo or Dolby Surround encoded content will be upmixed to a sort-of 5.1 format. 

Hear endeth the lecture 🙂 Good to hear everything is now working - happy viewing!

[KaiTa]

Thank you for your info. Just google the internet, there is no uncompressed audio like PCM 5.1 in broadcast. All 5.1 audio are compressed including those in Netflex.