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working around MP3 patents, what features do specific patents refer to
post Mar 31 2012, 16:29
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QUOTE (bawjaws @ Mar 30 2012, 17:00) *
I'm trying to get a handle on some objective measure of "really, really bad". I assume those are at the same bitrate. How much would you have to increase the bitrate on the hacked version for it to match (visually and/or audibly) the patented version? Is it even possible? How does that bitrate increase generalize to other types of audio such as speech or popular music?

Both examples above were compressed to 128 kbps. Increasing this to 320 did not create any visual or audibly difference.

The reason that the butterfly process can not be left out from the encoding is that the reverse butterfly process is performed in the decoding. I made a test where I removed the butterfly on encooding+decoding and ended up with a near-perfect result. No visually or audibly difference on the swept sine.

I think the reason for adding the butterfly process in the first place, is to handle the situations where one band is included but the next band is left out due to the perceptual filtering. I have not been able to create a synthetic signal where this is visible/audible though, expect at 32 kpbs where I did get some fuzziness on the graphics.
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post Mar 5 2014, 03:41
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I'd like to ask "how far we're into" this.

To me, reading through the list of patents is quite exhausting, given the sheer number, the (intentionally) obfuscated wording, and sometimes the rather poorly designed lists.

The idea that some expired patents might be enough to create MP3s that are patent-free, is more than appealing, and according to this list: http://scratchpad.wikia.com/wiki/MPEG_pate...Layer_3_patents quite a number of those have already expired*).

Depending who you ask, the time the last MP3 patents to expire range from 2015 to 2020, most seem to home in on around 2017 or later. But the idea is not to wait that long. I think the question - as the Op stated - is not when will be MP3 generally free, but what kind of MP3 is free already.

Could someone kinda maybe give me a red line, when key MP3 patents will expire, and when, what kind of MP3 will be free?

The problem that I have, is that even the titles of the MP3 related patents is hard to wrap my head around. I see several things expiring in 2014, but I have no idea which ones are key, etc. And I don't really know which patent "does what" to MP3. I assume some are less important than others.

*) That's the list I find most complete, I'd say. I know, it's poorly made, and it seems the entries are sometimes borked, so the sorting function doesn't work. It's still the best one I could find, though.

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post Mar 5 2014, 10:19
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I believe they have expired pretty much in Germany, but not in the USA where they were filed later.

Spoon http://www.dbpoweramp.com
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