How much compression happens with HDMI ARC and high-bitrate content?

ClementNerma

Novice Member
Hi there!

I currently own a TV with only an HDMI ARC output (not eARC). The soundbar I'm using it with as an eARC port, as well as two pass-through HDMI ports, which are unfortunately limited to HDMI 2.0.

So I'm currently using the soundbar with the HDMI ARC output with my inputs directly connected to the TV's HDMI inputs, and I read that HDMI ARC compressed high-bitrate signals like some Dolby Atmos content.

Now the question is: is there really that much of a difference? If you have a high-end home theater, I'm sure the difference can be heard, but with a $1000 soundbar with no physical surround speakers, I'm not sure I can actually tell the difference between the compressed and non-compressed version.

Is it just me or is the difference really small?
 

next010

Distinguished Member
HDMI ARC itself doesn't compress anything.

ARC supports compressed Dolby Digital 5.1 and DTS 5.1 audio formats, it supports uncompressed PCM 2.0 (stereo) and that's all you get.

Dolby Digital Plus 5.1 is an Atmos enabled variant of DD that can work over ARC were supported by the TV.

Anything other than the above will get downmixed to stereo PCM by your media player and then sent via ARC to the sound system.
 

ClementNerma

Novice Member
HDMI ARC itself doesn't compress anything.

ARC supports compressed Dolby Digital 5.1 and DTS 5.1 audio formats, it supports uncompressed PCM 2.0 (stereo) and that's all you get.

Dolby Digital Plus 5.1 is an Atmos enabled variant of DD that can work over ARC were supported by the TV.

Anything other than the above will get downmixed to stereo PCM by your media player and then sent via ARC to the sound system.
Ok, thanks for your answer :)
 

lgans316

Distinguished Member
Most importantly ARC is limited to 1 Mbps. Max we get via ARC is 768 Kbps (Atmos).
 

lgans316

Distinguished Member
I don't think that's quite important, it's more intuitive to think about what formats are supported instead of thinking of the bandwidth itself.

If it wasn't then we wouldn't be having e-ARC which opens up the possibility for streaming providers to switch to lossless streams than lossy streams due to ARC limitation of 1 Mbps. Chances of this happening in 1 in a million.
 

ClementNerma

Novice Member
If it wasn't then we wouldn't be having e-ARC which opens up the possibility for streaming providers to switch to lossless streams than lossy streams due to ARC limitation of 1 Mbps. Chances of this happening in 1 in a million.
To hear the difference between a 1 Mbps stream and a >1 Mbps one requires a really good equipment, that's already more than the bitrate of most audio CDs.
 

lgans316

Distinguished Member
To hear the difference between a 1 Mbps stream and a >1 Mbps one requires a really good equipment, that's already more than the bitrate of most audio CDs.

This is a very interesting point though. Some claim even the 768 Kbps Atmos on high quality streaming platforms sounds heavily compressed than the Atmos on disc. I experience this sh*tTy compressed sound with only 1 film on streaming and for the rest, they sounded very close but to each their own.
 

ClementNerma

Novice Member
This is a very interesting point though. Some claim even the 768 Kbps Atmos on high quality streaming platforms sounds heavily compressed than the Atmos on disc. I experience this sh*tTy compressed sound with only 1 film on streaming and for the rest, they sounded very close but to each their own.
This is likely more due to a bad compression than to the fact it is compressed in itself.
 

The latest video from AVForums

Podcast: Sky Glass, Epson Laser Projectors plus Home Cinema Subwoofers and More…
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom