Could someone explain to PCM sound to me?(sorry if old) - High-Def Digest Forums
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Old 02-19-2008, 10:16 PM
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Default Could someone explain to PCM sound to me?(sorry if old)

I haven't been able to figure out what PCM sound means. What type of receiver would I need to use this feature and what exactly is it? Thanks in advance.
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Old 02-19-2008, 10:23 PM
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technically it is "pulse code modulation" I believe. It is basically the digital equivalent of the analog source after it has been converted by a DAC (digital to analog converter) I believe. So it is what your music becomes in the digital realm. So if you have a receiver that has digital connections and such you would be dealing with pcm. Receivers that have optical jacks or hdmi etc. etc.
the newer hd audio codecs are either delivered as pcm or bitstream by the Blu-ray or HD DVD players to your receiver. You also have discs that have the 5.1 soundtrack as simply PCM 5.1 instead of having a TRuehd or dts-ma track.
This simply means the sound doesn't have the bandwidth of those lossless tracks I believe. The sound will not quite be of that quality, but will still be very good. So the phrase "pcm" can be used in a couple of different ways.
I am sure other members can explain it a little better.
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Old 02-19-2008, 10:29 PM
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Ah alright, then I should be able to use this then? I have my blu ray player using an optical cable for sound.
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Old 02-19-2008, 10:31 PM
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yeah the optical cable though doesn't give you the best hd sound unfortunately because it doesn't have the bandwidth needed for the Truehd or dts-ma. Not sure what happens with the discs labelled just "pcm." not sure if this sound is compromised or not.
someone else will have to answer that part.
you'll get something, but I just don't know if it will be the best you can get or not.
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Old 02-19-2008, 10:35 PM
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w/ optical cables you'll get 2 channels in pcm, I'd stick with the 5.1 dd or dts track instead of the pcm through your optical cable.
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Old 02-19-2008, 10:48 PM
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Yeah I have it set to those two options because I figured taht I couldn't use PCM since I didn't know what it was.
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Old 02-19-2008, 11:13 PM
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an instrument makes a sound and the sound is an anolog sine wave. the analog wave is digitized via Pulse Code Modulation (a digital representation of an analog signal) and then can be compressed into one of the familiar codecs - DD, DTS, lossy or lossless. it is recorded in this format onto whatever media storage disc - dvd, hddvd, bluray. you pop the disc in your player and decoders (DD or DTS, lossy or lossless) decode/decompress the codec back into PCM which is then converted back into analog by a DAC (digital to analog converter). the analog signal is then sent out to play over speakers.

sometimes the PCM signal is not compressed into one of the familiar codecs, but simply recorded as such on whatever storage disc. its is then read from the disc and sent to the DACs for conversion back into analog to play over speakers.

the decoders and DACs can be in your player, your receiver or both.

this should be enough for you to get through this great article that explains it all in more detail:
http://www.highdefdigest.com/news/sh...Explained/1064
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Old 02-19-2008, 11:56 PM
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Currently you can only listen to a 5.1/6.1/7.1 MultiChannel PCM if your receiver has an HDMI 1.2a or greater. If you receiver is connected via Opitcal or PCM Dig (RCA plug) then you can only listen to 2 channel PCM MAX or you can BITSTREAM the standard Dolby digital or DTS soundtracks.

Essentially the term bitstream just means that you are sending digital data bit by bit exactly as it is stored on the disc and the receiver is processing the bitstream and decoding the audio from it and then sending the audio through a DAC then to the AMP and from the AMP to the speakers.

With PCM the player is decoding the audio from the Bitstream on the disc to PCM and then sending the PCM to your reciever which then converts the PCM to analog through the DACs and then send it to the AMP which then hits your speakers. So basically the player is doing the decoding for you.
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Old 02-20-2008, 12:07 AM
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Actually, you only need HDMI 1.1 to get multichannel PCM.
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Old 02-20-2008, 07:56 AM
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Quote:
Originally Posted by ckelly79 View Post
Actually, you only need HDMI 1.1 to get multichannel PCM.
Even HDMI 1.0 will support multi-channel PCM.

http://en.wikipedia.org/wiki/Hdmi#HDMI_1.0

Quote:
HDMI 1.0
Released December 2002.

Single-cable digital audio/video connection with a maximum bitrate of 4.9 Gbit/s. Supports up to 165 Mpixel/s video (1080p60 Hz or UXGA) and 8-channel/192 kHz/24-bit audio.
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