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Dolby Digital or PCM audio?
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I was playing bluray disc last night night and i noticed i had the options of having the audio in either Dolby Digital 48Khz or PCM 48Khz/16 bit.  Which would give the best sound quality?  I have the dvd player audio connected via multi channel out to the amp. any advice please?

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Re: Dolby Digital or PCM audio?

PCM without a doubt. Although you should listen for yourself to see if you notice a difference - this will depend somewhat on your set-up and speakers.

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Re: Dolby Digital or PCM audio?

what does pcm stand for?

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Re: Dolby Digital or PCM audio?

Pulse Code Modulation. It's basically the form of sound that digital sound is decoded into to be outputted to the speakers. In the case of Blu-Ray, it is high-bit rate uncompressed audio that should be significantly better than the standard compressed Dolby Digital track.

Anonymous
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Re: Dolby Digital or PCM audio?

i thought dolby digital was the best, because used in cinemas etc? and yes, im new to this before you ask

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Re: Dolby Digital or PCM audio?

Nope, PCM is uncompressed, Dolby Digital is highly compressed. It's like the difference between a CD imported as a WAV file and a 128 Kbps MP3 in computer audio terms - the WAV file will be much better quality than the MP3 as no lossy compression has occurred.

 

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Anonymous
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Re: Dolby Digital or PCM audio?

I did watch Batman Begins in PCM, then I Bitstreamed DD Dolby True Hd sound, It did sound a duller then the PCM. So whats the point of DD True HD then. Experts and reveiws say in Dolby True Hd you are listing to the sound track the same as the master recording and as the director intended. Somebody please explain

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Re: Dolby Digital or PCM audio?

Interesting, my copy of Batman Begins doesn't have a PCM soundtrack. Anyway, the difference is, Dolby TrueHD (and DTS HD Master Audio) are lossless compression formats (like Apple Lossless or FLAC in the computer audio mode). This means they are compressed, but without any loss to the original detail in the soundtrack. As a result they take up less space on the Blu-Ray disc which might be required if there are lots of extras etc. Which format is used is entirely up to the studio that produces the disc.

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Anonymous
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Re: Dolby Digital or PCM audio?

i agree, if PCM is better quality, why would it be the second option the the gisc and not the default option, is this normal?

Anonymous
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Re: Dolby Digital or PCM audio?

professor, could you post a reply of the audio options from best to worst quality? im still confused...

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Re: Dolby Digital or PCM audio?
markthelifeguard:i agree, if PCM is better quality, why
would it be the second option the the gisc and not the default option,
is this normal?

Because the BD specification mandates that players must support Dolby Digital, DTS and Linear PCM.

Discs must have one of these formats, though there's actually no requirement for them to have the high-resolution variants of Dolby Digital or DTS, so Dolby is usually chosen as the default soundtrack as it's the simplest one for the player to downconvert between the HD and the standard version.

And of course Dolby Digital is the most back-compatible surround format when it comes to legacy surround amps and receivers.

In short, it's a compatibility thing.

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Re: Dolby Digital or PCM audio?
markthelifeguard:professor, could you post a reply of the audio options from best to worst quality? im still confused...

Well, in theory PCM, Dolby TrueHD and DTS HD Master Audio should be the same as the last two are just lossless compressions of the PCM soundtrack meaning once they are decoded (either onboard by the player or by a suitable AV amplifier), there shouldn't be any difference. However, many people maintain that a PCM soundtrack is better since it doesn't have to go through the decoding process - my own listening agrees with this.

After that, there are a couple of other lossy formats called Dolby Digital Plus and DTS HD High Resolution Audio. These are lossy compression formats so are not as good as the above three, but still contain more detail than the old Dolby Digital and DTS soundtracks. You will rarely see these used on a Blu-Ray.

Finally, there is regular Dolby Digital and DTS. These are the same formats as used on DVDs (although the bitrate is slightly higher on Blu-Ray, so they are still a bit better than the DVD equivalent).

You can read all about Dolby and DTS and the different formats at the links provided.

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Anonymous
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Re: Dolby Digital or PCM audio?

Nicely answered fella's. I was just about to ask the same thing ; )

Anonymous
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Re: Dolby Digital or PCM audio?

'The original poster has his bluray via 'multichannel' to his amp, so this sounds like analogue multichannel - which may well even further removed from comparing  PCM with Dolby/DTS bistreams.

Multichannel analogue requires the bluray player to read the 'digital' soundtrack and internally decode (if necessary i.e. not yet pcm channels) and then convert the pcm channels to the separated analogue 5.1 signals which are then fed out to a waiting amplifer which just amplifies.

I am not sure whether users can choose which digital format on the bluray for the player to use as its source to create the 5.1 multichannel out, whereas users do have the choice which format is sent via HDMI as a digital signal.

Anyone know?

 

Anonymous
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Re: Dolby Digital or PCM audio?

I have a Sony BDP-S550 Blu-Ray player with audio via the multi-channel outputs.  This player supports a whole host of analogue signals from 2 channel PCM up to 8 channel DTS-HD Master Audio. However you are limited to what source is available on the disc. Can't say for others manufacturers players.


Have not heard PCM 5.1 yet, but I do prefer DTS over Dolby Digital.  Greater dynamics, detail, volume. If I remember correctly DTS uses a higer bit rate than DD??

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Re: Dolby Digital or PCM audio?
shreddy:I am not sure whether users can choose which digital format on the bluray for the player to use as its source to create the 5.1 multichannel out, whereas users do have the choice which format is sent via HDMI as a digital signal.

Using multichannel outs, all that's happening is the soundtrack is being decoded onboard by the Blu-Ray player, rather than being decoded by the amplifier. So long as that player can decode all the formats onboard therefore, you can choose any of the soundtracks on offer.ÿ

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