Audio output always PCM when set to Automatic

[lubo68]

Hello,
I’m experiencing an issue with my new Google TV / Google Streamer device.

When the audio format is set to “Automatic”, the device always outputs audio as PCM, even with content that supports Dolby Digital, Dolby Digital Plus, DTS, or Dolby Atmos, and even though my AV receiver supports these formats.

My receiver is a Yamaha RX-V6A, connected directly via HDMI.
If I manually set the audio format to Dolby Digital, the multichannel signal works correctly.
So the issue seems to affect only the Automatic mode, which never switches to Dolby or other formats.

The same behavior occurs across multiple apps, including Prime Video and YouTube.
Could you please confirm if this is a known issue, and whether a fix or update is planned to improve the automatic audio format detection?

Thank you,
Luca

[branches78]

This is not an issue but the way how the "Automatic" option works where all dolby codecs get decoded to PCM internally by the device before it's output to the receiver, this is because the "Automatic" option uses something called "Dolby MAT".

If you want to see the Dolby logo popping up on your receiver, you can use the Dolby Digital Plus option, which it's just a stream method rather than a conversion of Dolby Digital and PCM to that codec, with the Dolby Digital Plus option you will also get Dolby Atmos inside Dolby Digital Plus.

[lubo68]

hi branches78,
thanks for your reply. so, you're saying it's just a logo issue — meaning the signal reaching the amplifier has the same quality as if it were dolby digital?
appreciate your help and clarification!

[branches78]

No, there is no issue at all, what happens is, Dolby created this "Dolby MAT" thing to decode Dolby Digital, Dolby Digital Plus (with and without atmos) and Dolby TrueHD (with and without atmos) to be decoded internally or inside the device instead of passing through the codec to the AV receiver for decoding.

Dolby says this method reduces delay in the audio and it provides other features such as audio leveling.

If you don't want those codecs to be decoded that way, then switch to the Dolby Digital Plus option in the device's audio settings, unfortunately, the Google TV Streamer doesn't have a passthrough option, otherwise that would be the best option to choose.

Did you test the Dolby Digital Plus option already?, that's the one I use with my Streamer.

[lubo68]

hi,
yes, I tried setting Dolby Digital Plus manually, and indeed my amplifier correctly shows the signal as Dolby Digital Plus.
what I was looking for was a way to keep the audio signal exactly as it is at the source.
I was wondering what happens when an audio track in dts format is played — I don’t really like the idea of converting one format into another.
passthrough would have been the ideal solution.
anyway, I’ll leave the setting on “auto” since your explanation about Dolby Mat makes sense to me.

thanks!

[branches78]

"what I was looking for was a way to keep the audio signal exactly as it is at the source"

Yes, I know and that's something a "passthrough" option would do but since it's absent then you don't have other option than to use the Dolby Digital Plus option, besides, the codec is not modified, the Dolby Digital Plus option is more like a transport method rather than a conversion method.

"I was wondering what happens when an audio track in DTS format is played"

It will play as DTS, no transcoding or conversion will happen unless you connect the device to a TV or soundbar without DTS support, however, DTS will not be converted to Dolby Digital Plus directly but it will decoded to PCM and it will be transported through to that Dolby Digital Plus output as well.