MP3...in Surround Sound

A number of people sent in the latest news from the fine folks at Frauhofer that they are expecting to have surround sound working for MP3s by July. The details are pretty sketchy in the article, but supposedly it won't be much more space per MP3s, and existing players will work with it.

Comments

Re:How hard will it be to convert?

[Sarojin]

Does your collection already have surround sound data? A bit pointless to convert, no new data to store.

conversion

[tomocoo]

You couldn't convert your mp3's to surround because the source is stereo... if you want surround just run it through PL2 for pretty good on the spot surround sound.

Ooh... MP3 goodness is all around

[Threni]

So you can have over sibilant vocals in front of you, warbly underwater bass behind you, and audio artefacts moving in circles about your head... I can't wait!

Nothing to see here.

[sokk]

Ogg Vorbis have had support for this for some while.

What I'm not sure of is if the support for "joint" surround is there. (Like joint stereo, only for surround)

Who wants to use a proprietary sound format, when they can use a much more appealing open format.

Re:Nothing to see here.

[nacturation]

Who wants to use a proprietary sound format, when they can use a much more appealing open format.

MP3: Everything supports it, which is very appealing for consumers.
OGG: Few products support it, not very appealing for consumers.

This is the old VHS/BETA debate again. Each one has various advantages over the other, but MP3 has already won mindshare and, as a result, is ubiquitous. In the end, consumers don't really care that Apple has to pay Fraunhofer $1 (or whatever) for licensing iPod's MP3 tech instead of $0 for OGG. After all, you'll never see Apple advertising a regular iPod for $299 -OR- you can get an iPod which doesn't play MP3 for $298.

Re:Nothing to see here.

[Anonymous Coward]

Yes, MP3 still remains extremely popular, but it is showing its age, and it isn't doing so well in other, less high-profile areas.

One of the places Ogg Vorbis has become surprisingly popular is in soundtracks for computer games. The no licensing fees must be one useful aspect, but there's also definite technological advantages such as better compression, more channels and - very important for sound effects and looped audio - arbitrary length samples.

I was really impressed to discover that Halo for the PC uses Ogg Vorbis for all its sound, and it's published by Microsoft! It's not alone, either - if you've bought a PC game at all recently there's a good chance the audio's compressed with Ogg Vorbis.

Is Ogg Vorbis successful? I'd say it was.

Vorbis can already do this :P

[Anonymous Coward]

Vorbis is also intended for lower and higher sample rates (from 8kHz telephony to 192kHz digital masters) and a range of channel representations (monaural, polyphonic, stereo, quadraphonic, 5.1, ambisonic, or up to 255 discrete channels)

http://xiph.org/ogg/vorbis/doc/vorbis-spec-intro.h tml

Silly?

[Davak]

Fraunhofer reproduces surround sound by adding to MP3 encoding extra information that describes the spatial characteristics of the main audio track.

If they are just adding information to the main track, why put that information in the file to begin with? Just let the user have a "spatial" encoder plug-in that jacks into winamp or whatever. Doing it this way increases the file size for everybody... people with and without surround systems.

Surround information should not be "created." It should be ripped and converted from the original source.

Before long we'll have the mp3 mess that we currently have with all the video codecs.

Davak

Re:Ipod?

[Anonymous Coward]

You should wait for the iPod Micro Edition. So small it fits in your anus and uses a methane-powered fuel cell. Oh, and it comes with a 64GB solid state memory chip and supports 6.3 Dolby Surround Extreme.

An optional accessory allows the device so play through bone conduction so that you don't have unsightly earphone wires coming out of the back of your pants.

Some Additional Tech

[Effugas]

Here's the deal.

By far, the most popular algorithm in use for surround sound encoding is Dolby's AC3 (I can say this, because it's on pretty much every DVD, and nothing comes close to its penetration even in the audio space -- not even DVD-Audio). AC3 itself is a pretty fascinating codec; one of the more interesting things about it is that each additional channel requires less and less bandwidth to tack on. This is because there tends to be massive correlation between channels -- either the same sound is coming from multiple directions, or a sound is coming from one direction and all the others are silent, or some combination therein. AC3 encodes this quite efficiently, and thus gets really high quality surround sound in surprisingly few bits.

I suspect they're engineering a similar mode for MP3 -- hopefully something a little nicer than Joint Stereo, which basically works by doing a mono mix and specifying which frequencies are louder in which channel. No, this doesn't work very well. Concievably, we could see something like VBR on a per-channel basis, but I suspect this would cause existing decoders to collapse. I do believe it's possible to place extra data between MP3 granules; I suppose they'll get their backwards compatible surround mode worked into there.

--Dan

Re:Some Additional Tech

[mudrat]

I suspect they're engineering a similar mode for MP3 -- hopefully something a little nicer than Joint Stereo, which basically works by doing a mono mix and specifying which frequencies are louder in which channel. No, this doesn't work very well. Concievably, we could see something like VBR on a per-channel basis, but I suspect this would cause existing decoders to collapse. I do believe it's possible to place extra data between MP3 granules; I suppose they'll get their backwards compatible surround mode worked into there.

That is precisely how MP3 mid side stereo mode works. It takes the sum of the channels (the common sounds) and encodes with a higher bitrate than the sounds that differ. Joint stereo is a mode where the encoder decides whether to use Mid-Side or true stereo for each frame depending on the stereo seperation. Joint stereo gives better results than true stereo at the same bitrate.

The mode you describe (mono with frequency info) is Intensity Stereo which few encoders even support.

Binaural Explained

[BigBlockMopar]

It would need a new connector, because you can only get stereo stereo from the iPod as far as I can tell.

For a surround output to an audio system, you would need a new connector offering at least 4 channels (Front L/R, rear L/R), line level. They'd probably make it straight-up 5.1, though.

And how do you get surround sound from a pair of headphones with only with a left and right channel?

Easily. Headphones have two channels (L/R), you have two ears (L/R). Your brain does some pretty heavy duty phase analysis to figure out where a sound is coming from. In fact, binaural recording is a technique where two microphones (L/R) are mounted on a form resembling the human head, but you need to wear headphones for the full effect.

A portable device could either use 4 channel headphones (expensive, requires 4 amplifiers to drive them, would increase battery consumption) or could use a DSP integrated circuit to decode the surround sound channels, perform the phase analysis done by the human brain, and send this synthetic binaural signal to regular headphones.

But it's still a lot of work for little payoff. Most of the use for surround sound in any form is movies. Music tends to be mixed to 2 channels from the perspective of a listener sitting in front of the stage, so I think its importance in a portable device primarily used for music is pretty limited.

And don't forget...

[Kjella]

One of the places Ogg Vorbis has become surprisingly popular is in soundtracks for computer games. The no licensing fees must be one useful aspect,

No licencing fees doesn't mean just that. It also means no overhead like getting a licencing deal set up, signed, making sure it's paid on time, in right amount, used only in accordance with the terms and so on. I'm seeing this first hand how much time is spent fiddling.

Just the process of going to someone with the authoroty to sign contracts and spend money in the company's name is wasting time, and time is money. That everyone, everywhere can use it for whatever is in itself probably worth as much as the licencing costs themselves.

Kjella