Different channels and recordings playing at different volumes

[Juichi]

Hi,
I updated our T4 unit to version 17.5 a few weeks ago and since then different channels and recordings will play at significantly different volumes. Initially I thought it was HD channels that played at a lower volume but this is not the case as different HD channels definitely play at significantly different volumes.
Even different recordings from pre update will play at different volumes. It's not just a minor difference, I will need to double the volume for some tv channels which then scares the crap out of us when changing to another channel.

I contacted support but they suggested I put this in the forum.
Any suggestions?

[MrQuade]

Any suggestions?

The new 17.5 update includes a big update to the way that the audio is downmixed.

Prior versions were limited to downmixing audio to a stereo signal, no matter if the audio track on your media or from Live TV was multi-channel or not.

The new firmware is smarter, in that it can detect if your audio equipment is capable of receiving multi-channel PCM audio and will instead downmix multi-channel soundtracks, to a multichannel PCM stream for playback. This is especially useful for any multi-channel AAC soundtracks, which were previously impossible to play back as multi-channel (as no audio equipment can accept raw-bitstreamed AAC audio over HDMI).

I suspect what is happening here is that your audio equipment is advertising that it can accept a mutlichannel PCM audio stream, when in may in fact not be properly set up for one. Some Dolby shows on live TV have soundtracks in Dolby stereo, and some come in Dolby 5.1, which may explain why some Dolby channels are louder than others on your equipment.

My guess is that when your audio equipment tries to play back mutli-channel audio, it is trying to send the centre and rear audio to speakers which are not present. Are there any settings on your amplifier or TV than would be affecting this? Can you tell us what audio equipment you are using?

You can also try disabling the downmixing option for Dolby audio, as long as your audio equipment can accept raw Dolby via HDMI. It may do a better job of working out what to do with a raw bitstream,

Another alternative would be to hook up your audio over optical SPDIF, as this is naturally limited to stereo PCM, and should cause your audio equipment to deal with the audio in the same manner as the prior firmware.

[peteru]

Make sure that your Beyonwiz volume control is set to around 90-95%.

[Juichi]

Thanks Mr Quade,

Thanks very much for the in depth response. Not sure I understood all of it but I get the general idea. I am basically running the Beyonwiz T4 through a Marantz amplifier via HDMI. The Marantz is outputing to 5 speakers by I assume 5.1. The speakers do work in 5.1 when playing bluray's but I will now pay more attention to what it is doing when playing the beyonwiz.

Your comment "You can also try disabling the downmixing option for Dolby audio", are you referring to a setting in the beyonwiz or the marantz amplifier?

I'll have to have a look at the back of the amp re the optical SPDIF suggestion to see if this is possible.

Thanks and will get back you once I have further info.

Juichi

[MrQuade]

If you press the AUDIO button from live TV you will get the audio menu.

Front there you can disable Dolby downmixing or DTS downmixing.

[gra]

there is no need for a connection through the optical SPDIF as your Marantz is receiving the audio signal through the HDMI cable
and will decode Dolby 5.1 from 9HD (ie ch80 in Newcastle)
if you have the [press the audio button on wiz remote] 'Dolby Digital / AC3 downmix' turned OFF
and you can only control the sound level with the Marantz

9HD Dolby 5.1.PNG (299.61 KiB) Viewed 1204 times

If you have 'Dolby Digital / AC3 downmix' turned ON you can control the volume on all channels with the wiz remote
and they should be very much the same

[MrQuade]

there is no need for a connection through the optical SPDIF as your Marantz is receiving the audio signal through the HDMI cable
and will decode Dolby 5.1 from 9HD (ie ch80 in Newcastle)

Do you have an alternative explanation as to why some HD channels are wildly different volumes compared to other HD channels?

I am suggesting the SPDIF connection to force the Marantz to receive the audio in stereo to see if the same volume issues continue.

I would also like to see the result of disabling downmixing though.

[peteru]

Not all HD channels use AC3.

[gra]

my config
T4 HDMI out > Yamaha HDMI in - HDMI out > Sony HDMI in
my FTA here is off Mt Sugarloaf https://ozdigitaltv.com/transmitters/NS ... t-Wallsend
My normal viewing is 'Dolby Digital / AC3 downmix ON' with TV speakers.
TV volume set and adjust sound with wiz remote.

test
set Yamaha to Straight sound program
looked at Yamaha input information
changed Wiz 'Dolby Digital / AC3 downmix' to OFF and ON to test
also listened for sound variations on all channels through TV and Yamaha (sound level by ear)
in each 'Dolby Digital / AC3 downmix' on/off state

observations
Dolby Digital 2.0 only on Channels 50 and 60.
Dolby Digital 5.1 only on Channel 80.
All other Channels are PCM Stereo.
Listening through TV speakers with 'Dolby Digital / AC3 downmix' ON
Channels 50, 60 and 80 sound a little louder than Ch 5, 6 and 8, etc.
Listening through TV speakers with 'Dolby Digital / AC3 downmix' OFF
Channels 50, 60 and 80 the sound is a little lower than Ch 5, 6 and 8, etc.
All other SD channels sound the same level.

--------------
Yamaha Input Information
with 'Dolby Digital / AC3 downmix OFF'

Channel 50
Format: Dolby Digital
Channel: 2.0
Sampling: 48khz
Bitrate: 128kbps
Dialogue: -4db

Channel 60
Format: Dolby Digital
Channel: 2.0
Sampling: 48khz
Bitrate: 256kbps
Dialogue: 0db

Channel 80
Format: Dolby Digital
Channel: 5.1
Sampling: 48khz
Bitrate: 384kbps
Dialogue: -3db

Channels ALL SD
Format: PCM
Channel: 2.0
Sampling: 48khz
Bitrate:
Dialogue:
----------------
with 'Dolby Digital / AC3 downmix ON'
Channel 50 & 60
Format: PCM
Channel: 2.0
Sampling: 48khz
Bitrate:
Dialogue:

Channel 80
Format: PCM
Channel: 5.1
Sampling: 48khz
Bitrate:
Dialogue:

Channels ALL SD
Format: PCM
Channel: 2.0
Sampling: 48khz
Bitrate:
Dialogue:
---------------

[prl]

The Marantz is outputing to 5 speakers by I assume 5.1.

A 5.1 setup will typically have 6 speakers: front left, front right, front centre, rear left, rear right & subwoofer.