What is LPCM? - AVS Forum
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post #1 of 9 Old 01-10-2009, 06:41 AM - Thread Starter
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hello all, i am trying to back up a blu-ray movie, i used tsmuxer and when i saw LPCM in the audio, i've read a little on this but cant find out what it is apart from being audio surround sound.
i have two options in TsMuxer
AC3 eng Bitrate: 448kbps sample rate: 48khz channels: 6
(there are two of these) and
LPCM eng Bitrate: 4608kbps sample rate: 48khz channels 5.1 bits per sample: 16bit

what is the difference in AC3 and LPCM? i only have a 5.1 set up on a Sony STR-DG510 receiver..
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post #2 of 9 Old 01-10-2009, 06:46 AM
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LPCM is uncompressed audio. Think of it as a .wav file and AC3/DTS would be like an .mp3 smaller due to missing information but representing the same audio track. You could also expand it to viewing Dolby TrueHD and DTS-HD as like a flac file. Smaller than a .wav but missing no information.
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post #3 of 9 Old 01-10-2009, 06:54 AM - Thread Starter
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oh so LPCM is better quality than AC3, If i chose AC3 would i need to keep both of them in or just one?
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post #4 of 9 Old 01-10-2009, 06:55 AM - Thread Starter
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and would LPCM play on my system?
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post #5 of 9 Old 01-10-2009, 07:27 AM
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How do you have your pc hooked to your receiver? Optical or Digital coax can only carry two channels of LPCM. If you have 6 analog cables or HDMI from a card that outputs full bandwidth then you can take advantage of the higher quality of the LPCM stream.
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post #6 of 9 Old 01-10-2009, 09:01 AM - Thread Starter
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pc is not connected, i'm burning the onto a blu-ray disc. and playing on a ps3 via optical, BTW what is better, going hdmi from ps3 to tv and optical to receiver or hdmi from ps3 to receiver then hdmi from receiver to tv?
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post #7 of 9 Old 01-10-2009, 10:40 AM
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HD Audio like LPCM will not pass over s/pdif (your optical connector). So if you want the benefits of that you will have to use HDMI to your receiver. This is assuming your amp will accept multi-channel LPCM over HDMI. I'd say the likelyhood is yes, but the spec sheet on the web is not clear.

However, it seems your amp cannot pass 1080p video, so if you have a 1080p TV you will be better off direct connecting the PS3 to your TV. The audio benefits may be marginal.
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post #8 of 9 Old 01-10-2009, 11:53 AM - Thread Starter
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thanks for your help..
i have got 1 more question i've been dying to get answered, and whilst i have your attention i hope you can help me again.
when i load my m2ts file into tsmuxer i always get these come up and there is 2 of each (4 in total)

AC3 eng Bitrate: 448kbps sample rate: 48khz channels: 6 (x2)

PGS eng presentation graphic stream (x2)

do i need these? if so why? and do i need 2 of each?
reason i ask is im trying to get the movie to fit onto a 25gb blu-ray disc.
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post #9 of 9 Old 01-11-2009, 12:15 AM
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Quote:
Originally Posted by shamoo_82 View Post

thanks for your help..
i have got 1 more question i've been dying to get answered, and whilst i have your attention i hope you can help me again.
when i load my m2ts file into tsmuxer i always get these come up and there is 2 of each (4 in total)

AC3 eng Bitrate: 448kbps sample rate: 48khz channels: 6 (x2)

PGS eng presentation graphic stream (x2)

do i need these? if so why? and do i need 2 of each?
reason i ask is im trying to get the movie to fit onto a 25gb blu-ray disc.

I don't know your disc. PGS I would say no. AC3 it depends what you want. One is probably the main soundtrack, one maybe a commentary or something (although those are normally 2-channel). hard to say without access to the disc.
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