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PCM Sound

Discussion in 'Acoustics' started by Snake Doctor, Nov 21, 2010.

  1. Snake Doctor

    Snake Doctor Active Member

    I am looking at the Sony BDP-S770 Blu ray Player so I have been reading reviews. The only complaint that I have seen is that it doesn't stream Dolby Digital 5.1 but steams PCM only.

    I was under the impression that PCM was a higher quality of processing then Dolby Digital 5.1. Since I have an Integra DHC-9.9 it should be able to handle PCM, am I wrong?

    My understanding is PCM is a method of signal processing and could be called Multi-Channel PCM surround.

    Please set me straight!

  2. Towen7

    Towen7 Well-Known Member Staff Member Moderator

    I cant speak to the Sony's performance but PCM is the what you get after the digital audio is decoded. So apparently the Sony is decoding the Dolby Digital 5.1 instead of just passing on the raw encoded data for your receiver to decode. The result should be identical regardless of which piece of gear does the decoding.
  3. soundhound

    soundhound Well-Known Member

    PCM (pulse code modulation) is the format that CDs use, and all digital audio workstations. It is the basic encoding for digital audio, and it is lossless.
  4. PaulyT

    PaulyT Behind the Curtain Staff Member Administrator Moderator Superstar

    Welcome, Snake! Good to see you posting here.


    I'm sure your Integra will handle PCM just fine. This is the same way my older gen PS3 sends data to my 885. As T7 said, the results are identical whether the DD is "unpacked" in the player or in the pre/pro. You're good to go!

    I've been considering getting a dedicated BD (+SACD) player, so I'd be interested to hear your impressions of this Sony if you do get it. Keep us posted!
  5. Razz

    Razz Well-Known Member

    one more tid bit...

    If your Sony decodes it's and sends it PCM to your Integra, then your Integra display will read "Multi Channel" and not any of the other readings such as....

    Dolbly Digital
    Dolby TrueHD
    DTS Master Audio

    The Integra needs to receive the signal via Bitstream in order to have that display.
  6. yromj

    yromj Well-Known Member

    First off: :text-welcomeconfetti: it's good to have you here.

    When I read your post I was a little confused because I couldn't believe that the 770 wouldn't decode DD (even my "old" S350 and "lowly" S370 decode every surround format), so I checked Sony's website.

    It turns out that the 770 will decode everything you asked about.


  7. PaulyT

    PaulyT Behind the Curtain Staff Member Administrator Moderator Superstar

    Right, also from that site, looks like it'll bitstream the various Dolby/DTS audio as well, including the HD formats. Which is why I don't quite get the complaint mentioned in the OP, about it only sending LPCM...
  8. Snake Doctor

    Snake Doctor Active Member

    It is good be included with you guys, thank you for allowing me to join your group. I will most likely be one who learns from you more then I will be able to share.

    The reason I posted the question is a friend of mine purchased the player and started complaining about not being able to stream DD. I told him he was crazy and he showed me this review from the same site you suggeted:

    I told him he was crazy there would be nothing wrong with the sound, but he persisted so I decided to ask those in the know.

    After explaining to him what PCM sound was he didn't believe me and I started doubting myself even though I couldn't believe Sony would make such a boo boo.

    Thank you,

  9. Snake Doctor

    Snake Doctor Active Member

    I think I am going to pick it up tomorrow evening. BBuy has it on sale with a 30 return policy how can you go wrong? After I have given it a good trial run I will let you know what I think.

  10. Snake Doctor

    Snake Doctor Active Member

    Thanks I didn't know it would display "Mulit Channel" that is good to know.

  11. yromj

    yromj Well-Known Member


    I was only thinking about the discs as well. The fact that it doesn't bitstream DD5.1 is something that should be addressed, but it's not a big deal either.

    DD is simply a means of compressing a PCM data stream (ala "zipping" a word document). When the DD is decompressed ("unzipped"), the result is a PCM data stream. That data stream will be the same regardless of which device (the player or the pre/pro) does the decompressing (though neither will match the original data stream because DD is a "lossy" (ie, not lossless) format).

  12. Snake Doctor

    Snake Doctor Active Member

    So will that affect the sound? I didn't think it would make any difference with sound regradless if I was streaming or had a blu rae disc. If I understand what you are saying there would be a difference...how big a difference?
  13. PaulyT

    PaulyT Behind the Curtain Staff Member Administrator Moderator Superstar

    No, DD5.1 bitstream vs PCM doesn't make any difference in sound, assuming your receiver/processor can handle both formats.

    One customer-type (informal) review of the S770 that seems to come up often in google searches complains about no DD5.1 from internet video (netflix etc.). I don't know if that means it's unable to get surround sound for internet video at all, or (I think more likely) that it just converts to PCM. My guess is that many folks just don't understand what PCM means, and mistakenly assume that "PCM" means stereo only.
  14. Yesfan70

    Yesfan70 I'm famous now bitches! vvvvv Famous

    I'm sort of one of those folks. I know you can have surround sound with PCM, but I have always look at PCM as being (9 times out of 10) 2 channel uncompressed audio.

    So looking at that last post about no 5.1 with internet streamed content, I'm guessing that reviewer is "right", but it's a matter of the content not being encoded that way from the start. In other words, it's not the player's fault. That's just a guess on my part.
  15. PaulyT

    PaulyT Behind the Curtain Staff Member Administrator Moderator Superstar

    Yeah. Well if I do get an S770 (which I'm still seriously considering), that'll be one of the first things I check. I'll just be sure to buy from somewhere with a good return policy. ;) It's also the sort of thing that may well have been (or will be) addressed by a firmware update.

    PCM means "pulse code modulation" which is just a technique for encoding an analog signal into digital. It basically just means uncompressed digital audio. But even stereo PCM is "multi-channel" in that there are two channels for L/R. Surround sound just adds more. I think perhaps some receivers don't necessarily show how many channels are coming in, so if someone sees "PCM" they just assume stereo. My 885 will tell you how many channels; dunno how other models/brands handle it.
  16. yromj

    yromj Well-Known Member

    It won't affect the sound. I was trying to show that the sound is going to be converted to PCM by SOMETHING (whether it be a processor in the player or the pre/pro) and it doesn't matter where.

    In any case, it appears to only affect streamed content. That really makes it insignificant, IMHO, because any difference that could be caused by the difference in processors (which I still contend is exactly zero) would be GREATLY outweighed by the increased compression used for the online version of the sound.

  17. Snake Doctor

    Snake Doctor Active Member

    Interesting. I thought that PCM was what you ended up with when you uncompressed DD5.1. If that was the case I wouldn't expect any drop in sound performance.

    I think I am going to get it tonight at Best Buy my understanding is they have a 30 day return policy. Has anyone had any dealings with them?

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