Secrets Q & A

Decoding Audio Formats

Question:
I have a Panasonic DMP-BD655 Blu-ray player connected to an Onkyo TX-SR805 receiver, with DefTech Mythos STS speakers for the fronts. I know that the Onkyo is capable of decoding losses HD audio formats sent via bitstream from the Panasonic.

My question - For best sound quality, should I have the Panasonic bitstream lossless audio and have the Onkyo do the decoding? Or, will I get better sound by having the Panasonic do the decoding?

- Venkat Iyer
Chicago, IL

Answer:
When the first Blu-ray players hit our equipment racks, receivers and SSPs hadn't quite caught up and the best of them, those with HDMI input, could only accept multi-channel PCM audio data so the Blu-ray players would decoded the soundtracks and output multichannel PCM. Consumers demanded that receiver and SSP manufacturers incorporate the HD audio decoding so that players could send the packed audio data to them and thus transpose the decoding to what was perceived as a better place in the chain. The irony is that, while a logical inclusion for receivers and SSPs for other reasons, the benefit people thought would be there simply wasn't:

- Firstly it makes no difference whatsoever in terms of audio quality. Unpacking DTS HD Master, Dolby TrueHD, etc, is not a variable, is not open to interpretation, and is not done "better" by one device or another. Any and all variable processing (EQ, THX, bass management, etc) happens after the PCM audio data is unpacked so there is no advantage to the receiver or SSP decoding the bitstream over the player. You can think of it like a Word document on your PC which you put into a Zip file: no matter who or what unzips it, that Word document will always come out the same.

- Secondly you actually loose functionality when you configure a blu-ray player to output the bitstream: it cannot deliver mixed audio such as UI sounds, PnP audio overlay, etc. Those features can only work when a Blu-ray player is setup for multichannel PCM output and as such, given there is no downside, is always our recommendation.