PCM or Bitstream from Blu-ray Player

Which is best, PCM or bitstream from a Blu-ray player to the A/V receiver? I have reviewed many posts on various forums, but I have not found a definitive answer. I have an Onkyo TX-SR608 AVR and an LG Blu-ray player capable of decoding DTS-HD Master Audio and Dolby TrueHD lossless audio. I view Blu-ray discs and regular DVDs about 50/50; certainly Blu-ray when available. Should I set the player to output PCM or bitstream? Why one over the other? Do I need to tell the AVR which stream is incoming?

James

In terms of audio quality, it doesn't matter; the results should be identical either way. I suppose there might be a slight difference between the decoder in the player and AVR; to find out, all you have to do is try it both ways and see if you hear a difference. I bet you won't. And you shouldn't have to tell the AVR which stream to expect; it should detect and process the stream automatically.

The main reason to use PCM instead of bitstream is that with PCM, you can hear any secondary audio that might be on the disc—things like commentaries during the movie and sounds when you click on a menu item. In most cases, if you select the bitstream output, the player does not mix the secondary audio with the main soundtrack, so it is not sent to the AVR. Some players offer a "bitstream/re-encode" option that re-encodes everything to standard DTS or Dolby Digital, and you can hear the secondary audio in this case, but I don't recommend it because the lossless audio is converted into lossy audio, lowering the sound quality.

Home Theater reviewer Tom Norton generally uses the bitstream output, because that way, his Integra pre/pro indicates exactly which format he's listening to. If he selects the PCM output, the pre/pro only indicates that it's multichannel. Your Onkyo AVR does something similar as seen in the drawing of its display above, so if you want to be sure of which format you're hearing—and you don't care about the secondary audio—use bitstream. Otherwise, use PCM so you can hear the secondary audio.

If you have an A/V question, please send it to askhometheater@gmail.com.

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COMMENTS
JayMargolis's picture

It's important to distinguish this largely academic issue (you're not going to decode Dolby Digital better in one device than another in general as it's digital and non-lossy decode) from the very real issue of how to get DTS 7.1 HD Master Audio out of the player. For that you will need something like an Oppo BDP-93 with actual on-board decoding and multi-channel outputs.

mailiang's picture

HDMI is the way to go unless your are using an older receiver. Multi channel outputs are analog, which means all the bass management is done by the player. In most cases, even with the higher end players like those from Oppo, bass management falls short in terms of flexibility and accuracy when compared to those used in most Prepro's and AVR's. Besides, It's often better to go from digital to digital, rather then from digital to analog and back to digital when listening to lossless or even lossy audio formats.

Ian

adriandeftones's picture

Also if you are using TOSLINK instead of HDMI in case of old AVR's, your PCM output from the Blu-ray player will be 2-channel only. Your only way to go for discrete surround sound is bitstream, that normally will downconvert Dolby TrueHD to Dolby Digital and DTS MA to regular DTS.

techguy378's picture

If you're using a Windows 7 PC with HDMI for Blu-Ray playback then you'll get significantly better audio with bitstreaming compared to multichannel PCM. Here's one example: If you play a Blu-Ray disc with 24-bit/96KHz audio then Windows 7 will play it back at 16-bit/48KHz if you leave the Windows audio settings at their default.

albert26's picture

Hello Sir ,,all the above comments are true,I was set the Bluerays
to PCM,it does sound better,,raise the hrz ratio to 196 if the player allows,,& always buy a Digitall uncompressed HDMI ,such as
Wireworld,STRAIGHTWIRE,MADE in Florida state,,lifetime warrantys
there's all different types of geomotry in these cables,& postivly will give you better picture & Sound,,I promise.
Brian
www.Floridahometheatersplus.com

mailiang's picture

Personally, I have found that the best deals for interconnects come from on-line dealers like Monoprice. They offer excellent build quality and will get the most out of your audio/video system at very reasonable prices. Even C-Net uses and recommends them. As far as PCM verses bitstrem is concerned, I've listened to a lot of systems both ways, and like Scott, I have found little or no audible difference in sound quality.

Ian

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