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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.
Whats this mean for the Ipod? Firmware upgrade? I was going to buy but if I should wait for a 4th gen Dolby 5.1 edition to come out I will.
Does your collection already have surround sound data? A bit pointless to convert, no new data to store.
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MP3 is an outdated CODEC, the only reason it's still in use is because of compatibility. If you start adding extra features that break compatibility people will just move to a better quality CODEC with the same features (and possibly more).
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.
What would be the point of converting?
You'd just add extra headers and increase file size. If you want to dynamically alter sounds in 3d space dependant on temporal and frequency factors a plugin might be more appropriate. How often do you listen to all of your mp3 collection?
I don't know why you'd need to change anything... I get surround sound right now with my ordinary stereo MP3s. It's called Dolby Pro Logic :-)
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!
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.
Now, if only you can get MP3's to play in quad, and go KERCHUNK every few minutes, and my 8-track flashback to 1973 will be complete!
Don't blame Durga. I voted for Centauri.
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)
h tml
http://xiph.org/ogg/vorbis/doc/vorbis-spec-intro.
MP3 is and was always proprietary...
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
Hmmm... this might be a good time for then to try to 'enhance' the MP3 standard by adding in DRM as the various **AA's (damn them to Heck!) have been urging for years.
I think I'll sit out on this one thank you very much. I like music and everything, but stereo is more than adequate for me (If I want 6 channel sound, I'll just watch a DVD...)
Finally Frauhofer will catch up to the innovation that Microsoft made more than a year ago. (Oh the irony) Windows Media could do this since its last realease. http://www.microsoft.com/windows/windowsmedia/9ser ies/Gettingstarted/DemoCenter/AudioQuality.asp?pag e=6&lookup=AudioQuality
Was MS first to have this technology for the mainstream consumer???
Hmm, how does your audio format get any more proprietary than before when the folks who developed it in the first place extend it?
Grandparent is essentially right. MP3 *is* an outdated codec, which is only still here because of it's universality (don't get me wrong - this is a big benefit). While these added features may not actually break the old standard, they do result in bigger files with no discernable benefit for the vast majority of people. If you want to examine the success of previous add-ons to the mp3 standard, take mp3-pro - it's not exactly all over the place. People will take standard mp3 for it's universality, and choose a superior codec (AAC, OGG, MPC, whatever - even WMA) when they aren't concerned about compatibility.
Now you'll only need 2 computers to listen to Zaireeka !
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
Not to mention how the method of adding pretend "surround sound" that they're proposing is retarded.
For what it's worth, MP3Pro also wasn't really backwards-compatible, even though it claimed to be. In a format that didn't support the extensions, it cut off the entire high end and it sounded like absolute shit. It remains to be seen if the same issue will be seen in these surround MP3s, but if it really doesn't add too much, like the article is implying, I don't imagine it will be a cataclysmic failure.
Besides, there aren't that many surround-sound audio CDs to rip yet, so something like this wouldn't gain in popularity until a more popular codec has already superseded it. I wouldn't worry about it gaining any type of dominance.
Yep -- there is SACD, which is kind of like DVD audio with the 5.1 encoding, but if you put a hybrid SACD disc in a regular CD player, you get the front stereo pair. It's been around for a while but isn't incredibly hot right now. Sometimes you can find SACD discs at Best Buy and such.
The system you mention is "Dolby Stereo". But "sum" and "diff" aren't the correct terms. Any signal that is in 100% phase on both left and right will end up in the center channel. Signals that are out of phase end up in the rear.
Now "Dolby Stereo" sounds like it is, well, stereo. So the marketing department decided at some point that it should be called "Dolby Surround", which is fair enough. "Pro Logic" is "Dolby Surround" for use in home A/V amps, but with "Pro" electronics (logic). Another marketing term for the same thing.
That system should work fine on any MP3. Stereo MPEG audio on DVDs (so not the Dolby Digital or DTS tracks) quite often have Dolby Stereo/Surround encoding on them as well.
The truth is that the BBC article doesn't have enough information and I think "Surround" is used as a general term to indicate more than two channels of audio. So no way of knowing what they actualy mean.
From the article, again:
There's no extra channels, just an extra layer telling the player how to manipulate the two existing audio channels to obtain a surround-like effect. While the merits of this approach alone make me skeptical, what really bothers me about this is how different players are all going to have completely different implementations of using this extra layer of data to manipulate the audio channels, meaning we're going to have no consistency whatsoever with how it even sounds.
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.
Fire and Meat. Yummy.
I don't see why they would put the time into their "teenager" codec to put surround sound support into it. Especially when mp3 is mainly used for music and isn't technically for video. Where as they could have spent the time to hammer out multichannel support for aac, so then mpeg4 would have multichannel support. So then they'd have a codec for video AND a codec used for just audio with multichannel support. The only thing i see this good for is Xvix and Divx videos. While these can be encoded with AC3 5.1 support, its rare that anyone does it. They usually opt for VBR MP3 with an average bitrate of 192k. So now it looks like they can use mp3 still and get the 5.1 Cmon mplayer! make sure you get support fast.. my xbox needs it!
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
Live today, because you never know what tomorrow brings
See ISO13818-3 which describes MPEG2-audio (which is an extention of the original mpeg audio standard - iso 11172)
ISO13818 describes
* the Low Sampling Frequency extensions (which describe encoding mpeg audio at 16/22.05/24 kHz). This is already incorporated in most encoders.
* 3/2-stero+LFE (Section 0.2.3.2 describes the various configurations e.g. 3/2, 3/1, etc)
For a very brief moment when I had too much time, I worked on getting the multichannel stuff working in tooLame (the layer2 mpeg audio encoder) and the way it works is this:
1. The encoder works out the overall bitrate for all the channels (X bits)
2. The encoder assigns some bits (Y) to be used for the backwards compatible 2-channel stereo so that all compliant decoders will work. Y gt X. (The way the 5 channels are crosstalked and cancelled out to get 2 stereo channels is complex. Read the standard if you want more info).
3. There will then be Z bits (Z=X-Y) left over for the storage of the other channels. (Referred to as "Ancillary data").
4. The beginning of the mpeg audio frame has a flag set so that compliant decoders know about the extra info.
5. Old decoders won't grok the flag, and so they'll just read the stereo info, skip over all the extra info and then find the next bit of data they do understand.
The outcome of all this is that you may have a 512kbps mpeg audio stream which contains 256kbps of the stereo information and then 256kbits of "extra" info that is used to reconstruct the full 3/2 channels of sound.
There is a problems with this however. Compliant MPEG audio streams have a maximum bitrate as set out in the original MPEG1 standard (11172). For example, the maximum total bitrate of a 44.1kHz mp3 file is 1011 kbps. However, when you do really high bitrate multichannel stuff, you can exceed this limit: in this case, the MPEG2 standard suggests using another file to store the information (referred to as the "extension bitstream").
Hope this helped someone.
later
mike
Cool, but useless.