PCM Displaying On My Receiver

[+Mystic MVC]

I had my computer hooked up to my TV through a DVI to HDMI connector as well the a SPD/IF cord going from my GPU to my sound card.

When I play video files off of my computer (on my TV), PCM lights up on my receiver. Can somebody explain what the benefit or what it does?

[Phantom Helix]

PCM is completely uncompressed audio (Like WAVE files for CD's) if you get a Blu-ray movie and it has PCM uncompressed 5.1 as an option it is a better version of the audio than even DTS HD MA.

However when you see that on your receiver all it means is that is that the audio signal coming from your computer is not being pre-processed into a format that your receiver can output (Such as Dolby Digital) ,

Because it is capable of outputting the RAW audio on it's own, or processing it into Dolby Digital inside the receiver instead of the source it is coming from.

Did that help ? im a lil tired and not sure if i explained that correctly

Basically it means the audio has not been changed in anyway from your computer to your receiver

Edited November 23, 2009 by Phantom Helix

[Joel]

if you get a Blu-ray movie and it has PCM uncompressed 5.1 as an option it is a better version of the audio than even DTS HD MA.

Better in what way? It's an alternative, yes, but better? I'd like a source on that, please.

[+Mystic MVC]

PCM is completely uncompressed audio (Like WAVE files for CD's) if you get a Blu-ray movie and it has PCM uncompressed 5.1 as an option it is a better version of the audio than even DTS HD MA.

However when you see that on your receiver all it means is that is that the audio signal coming from your computer is not being pre-processed into a format that your receiver can output (Such as Dolby Digital) ,

Because it is capable of outputting the RAW audio on it's own, or processing it into Dolby Digital inside the receiver instead of the source it is coming from.

Did that help ? im a lil tired and not sure if i explained that correctly

Basically it means the audio has not been changed in anyway from your computer to your receiver

So if I'm watching a movie through my PC and it is showing PCM, what should I set my receiver to? Something like All Channels, Stereo, one of the PLII settings/Neo?

[Phantom Helix]

Better in what way? It's an alternative, yes, but better? I'd like a source on that, please.

It is the Raw Audio source, why is that hard to explain?

The bit rate is higher than compressed audio such as Dolby Digital, AC3, Dolby TrueHD and DTS/DTS HD MA, PCM is around 4.6mbps while DTS HD MA is around 1.9mbps

http://en.wikipedia.org/wiki/PCM

http://en.wikipedia.org/wiki/DTS-HD_Master_Audio

http://en.wikipedia.org/wiki/TrueHD

So if I'm watching a movie through my PC and it is showing PCM, what should I set my receiver to? Something like All Channels, Stereo, one of the PLII settings/Neo?

If your receiver is showing PCM that means it is not resampling the audio and you are getting it the way it was truly intended, Changing your receiver to DD ProLogic/ProLogic II MOVIE or ProLogic II MUSIC is forcing the hardware to resample it before outputting to your speakers.

The "Gain" on PCM is standardized thought so you may notice that a DTS, TrueHD or other audio encoding may be louder than PCM, that is caused by the gain level being digitally (generically) increased when it was encoded, which is a common if not guaranteed result of the process.

as for setting your speakers that is up to what your system has, is it a 5.1 surround? if yes than all channels will be fine to get surround.

I have an older Sony 5.1 surround system and i can A.F.D Auto which is an auto-select setting based on what it can read on the audio it gets, or i can choose any of the Dolby settings (this however is forcing the re-sampling in the receiver's hardware)

My preference thought is C.ST.EX__C Which just changes how the audio levels are for certain speakers, it is a more "Movie theatre" type configuration than normal Surround.

Really though unless you are a serious AudioPhile like me you will never notice the quality difference. in fact My Logitech Z-5300 THX 5.1 speakers for my Computer have a far superior sound output quality than my 10 year old Sony Receiver, so equipment is a major factor.

And since your OP was about playing stuff from the computer to the receiver unless the video/audio player is genuinely passing the raw audio source for the audio or video you are watching to the receiver is not always a feature, depending on the player software.

I suspect that your computer setup is simply passing on the audio signal in a PCM format since you are using a SPD/IF connection, now what happens from the "Source" to the audio/video player to the SPD/IF is dependent on the the features/functions of your player software.

DVD player software should have all the correct features as long as you have the settings in place correctly.

Players like VLC have Audio Pass-Through in the advanced settings, however that relies on the "Source" file having the correct encoding.

My final suggestion to your OP is just to play around and choose what "You" think sounds best, in the end that is all any of us can do anyway, thats why it ****es most of us off when others play with the radio in our cars lol

[Joel]

It is the Raw Audio source, why is that hard to explain?

The bit rate is higher than compressed audio such as Dolby Digital, AC3, Dolby TrueHD and DTS/DTS HD MA, PCM is around 4.6mbps while DTS HD MA is around 1.9mbps

http://en.wikipedia.org/wiki/PCM

http://en.wikipedia.org/wiki/DTS-HD_Master_Audio

http://en.wikipedia.org/wiki/TrueHD

A TrueHD or DTS-MA track, once decompressed, is bit-for-bit identical to the same movie's PCM track. PCM just takes up more space to accomplish the same thing.

It's hard to explain because you're just plain misinformed.

[Phantom Helix]

A TrueHD or DTS-MA track, once decompressed, is bit-for-bit identical to the same movie's PCM track. PCM just takes up more space to accomplish the same thing.

It's hard to explain because you're just plain misinformed.

That is true only depending on how your audio system operates, however PCM is included on some Blu-ray discs along with DTS HD MA so you have an option of no hardware or software level decoding/decompression, which depending on your system can cause degradation on the final output.

[+Mystic MVC]

Thanks for the informative post Phantom. For the most part I have just been using WMP or Media Player Classic to watch movies but I'll stick to using All Channels.

[Joel]

That is true only depending on how your audio system operates, however PCM is included on some Blu-ray discs along with DTS HD MA so you have an option of no hardware or software level decoding/decompression, which depending on your system can cause degradation on the final output.

CAN, maybe, never proven to. But you said outright that PCM was better than TrueHD or DTS-MA. That's not what you're trying to say now, and that's where I'm having an issue with your statement. You may have a personal dislike for all things compressed or not, it really doesn't matter. But you can't make a blanket statement like that as if it's a fact.