Will Bueché



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PS3 audio, finally understood by me

Posted in Personal by Will on Sunday, September 27th, 2009 ~ 1am

After hours of studying, I’ve developed the following summary of the Playstation’s choice between “Bitstream” or “Linear PCM” audio output:

If your Playstation3’s audio connection to your receiver is an optical digital cable
, you really have no choice but to set the Playstation3’s audio setting (located under video setting) to “Bitstream”, because only a raw bitstreamed audio signal has a chance of being multi-channel over an optical digital cable. If you set it to “Linear PCM” instead, the audio your receiver will receive over the optical digital cable will be simple stereo, all channels having been downmixed by the Playstation3 into simple stereo. Don’t blame the Playstation3 though — optical digital cables can only fit 2 channels worth of audio.

It may be a bit counter intuitive, but the raw data that is sent over the digital audio cable when the Playstation3 is set to “Bitstream” is more compact than the decoded audio channels that would be sent when the Playstation3 is set to “Linear PCM”. That’s why Bitstream is the only way to get multichannel audio through an optical digital cable. (To overcome this counterintuitive-ness, think of the raw data as a compact zip file, and the audio channels that emerge from that raw data as expanded files.)

Now, on the other hand, if you’ve got HDMI connection for your audio, then you don’t really have to worry. Either “Bitstream” or “Linear PCM” will deliver multichannel audio properly, in pretty much the same way. There’s one small difference that affects only people with a 7.1 speaker set-up — those folks would want to choose “Bitsteam”. But for everyone who only has a 5.1 speaker set-up, the choice of “Bitstream” or “Linear PCM” is practically irrelevant (though considering the next paragraph’s note, “Linear PCM” may be the best choice).

A sidenote: Sometimes picture-in-picture commentary tracks or picture-in-picture extras that play along with the feature (aka “bonus view”) demand switching to “Linear PCM” in order to hear everything! This odd situation affects both HDMI and digital optical users equally. Just remember to set it back to “Bitstream” afterwards if you use a digital optical cable! (HDMI users with 5.1 speaker set-ups, well you may as well leave it as “Linear PCM”). You may ask, why the heck does this situation exist? Because the inventors of BluRay honestly believed that by the time BluRay was on the market, everyone would have receivers with HDMI audio inputs, or would just be listening via their LCD televisions (which all have HDMI inputs) and as such could set their player to “Linear PCM”. They did not appreciate how many people would still be using older receivers with optical digital cables, who would be forced to use “Bitstream” to get surround sound. As such, the “bonus view” audio — and even some menu sounds — wound up on the outside, in the cold. It simply didn’t fit inside the limited bandwidth of the optical digital cable.

A sidenote: the older Playstation is unable to use the newest form of dts audio, which is called dts-HD MA. It gets around this problem by extracting the “core” dts from the dts-HD MA — which the developers of dts-HD MA were kind enough to leave inside of dts-HD MA when they invented dst-HD MA. Only real audiophiles will notice. But Sony did manage to fix this in their newest version of the Playstation3, the Playstation3 Slim.

A clarification:

Your Playstation actually has 2 menu items requesting you to select either “Bitstream” or “Linear PCM”. They’re both in the video settings. One is called
“BD/DVD Audio Settings (HDMI)”, and one is called
“BD Audio Settings (Digital Optical)”.
Notice that the first says “BD/DVD” but the second says only “BD”? Yeah? Well don’t get hung up on that; I have a sneaking suspicion the “/DVD” was deleted from the latter only so the entire phrase could fit on a single line. In fact the only part of each phrase to focus on are the “(HDMI)” in the first menu item and the “(Digital Optical)” in the second menu item. My recommendation, based on the info presented in the paragraphs above, is to:
set the “BD/DVD Audio Settings (HDMI)” to “Linear PCM”, and
set the “BD Audio Settings (Digital Optical)” to “Bitstream”.

And finally, a moral: Buy a new receiver with HDMI audio inputs. Otherwise, you may go nuts. Not only will it be impossible for you to set something wrong and wind up accidentally listening to mere stereo, you’ll avoid another problem owners of older receivers face: older receivers not understanding what kind of multi-channel signal they are receiving, and erroneously trying to apply pro-logic (fake surround sound processing) to it. Believe it or not, that situation exists for owners of the old Kenwood VR 407 (from 2002) and other receivers built a few years before BluRay and all of its many audio formats existed.

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  1. Rodney said,

    on September 27th, 2009 at 2:34 pm

    This is marvelously technical. I’d like to say I understood it, but I’ve become totally techno-phobic lately. I am, however, thinking of getting a Playstation3 for a friend of mine for X-Mas.

  2. Will said,

    on September 28th, 2009 at 11:40 pm

    That’s a really nice gift. The Playstation3 Slim is a great machine — the Slim is better than the Playstation3 that I have. It has some quirks, Sony being not far removed from Microsoft in terms of not being inclined to make intuitive interfaces, but, once you learn the tricks it works well. It is sad that technology remains so stupid, however. And by stupid, I mean it has no intelligence — the user has to know what he or she wants and then has to figure out the way to make that happen, rather than the machine trying to find it’s own way after being told what one wants.

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