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working around MP3 patents, what features do specific patents refer to
bawjaws
post Mar 16 2012, 13:25
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I've been reading some of the mp3 patents and it appears to me (as someone with no general legal experience, no deep knowledge of patents, or great understanding of the inner workings of mp3) that some of them could be worked around easily if you cared more about avoiding patents than you did about making full use of the specification. And since many of the patents are expiring already a workable patent-free subset may already, or soon, be possible even before the very final patent expires around 2017.

To give a simple example, one of the last patents to go (according to http://www.osnews.com/story/24954/US_Paten..._MPEG-2_H_264/) is US patent 5812672:

"Method for reducing data in the transmission and/or storage of digital signals of several dependent channels"
http://patft1.uspto.gov/netacgi/nph-Parser...tnumber=5812672

This seems to be a patent on the concept of switching between different joint stereo modes based on the audio content. So a simple workaround would be to only produce mono files. No stereo means no joint stereo, means no switching between joint stereo modes, means absolutely no possible infringement of this particular patent (and if your intended input or output format was mono in the first place, absolutely no loss in quality compared with patented methods). If similar could be done for each of the remaining 12 (according to the link above) patents then you could include such an encoder in F/free software, and distribute mp3s created with such an encoder in games or in streaming radio without paying any fees and have them decoded by any standard-compliant decoder.

Note that I think for the example above, you could easily have stereo files without infringing the patent as long as you only had one stereo mode per file but I went with the mono example because it makes the non-infringement clearer. Maybe you could be very sneaky and still switch modes as long as you did it in a very slightly different manner from that described in the patent and get some further improvment in quality as a result. For all I know, maybe lame already does this differently/better than the patent. But that's just icing on the cake. Having *anything* that produces compatible mp3 files, even at a cost of reduced quality or flexibility would be a start and be useful to *someone* since mp3 is generally used today for compatability reasons rather than because of its technical qualities.

I'd like to know if there has been any concerted effort by people who actually understand this stuff (on both the legal and technical side) to create a functioning mp3 encoder and/or decoder that works around all known patents. Is it possible? At what cost in functionality, quality, bitrate etc. If not, which particular patent(s) are the blockers which you can't possibly work around and without which you cannot have a compatible, non-ear-killing mp3 and when does the last of them expire?

(There's also the interesting sub-issue, which seems to apply to most modern lossy codecs, which is if your encoder is doing something incredibly clever (and/or patented) to decide when to switch between different encoding modes, but your decoder is dumb as a rock and simply does what the encoded file tells it to, does the patent for the encoder process have any impact on the decoder?)

I'm guessing the messed up nature of patents means no-one with an actual business to protect is going to want to risk this when there are feasible alternatives (e.g. pay the fees or use vorbis) but it seems like it might be an interesting intellectual excercise anyway and some free audio tools (e.g. Audacity) might include such a thing if the general consensus was that it was possible (just as some people would avoid Vorbis because "you can never be sure" about patents, but it hasn't stopped most reasonable people).

This post has been edited by bawjaws: Mar 16 2012, 13:29
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Garf
post Mar 20 2012, 11:41
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I found several other lists of patents, including the ones you didn't list, put them in a table, and read through the claims of all of them. I'm not sure all of the expiration dates are correct, this is tricky to determine.

Based on what I know of the MP3 standard, writing a patent free encoder should be possible the 24th of September 2013, but not before that. I am not so sure about a decoder, as many patents describe systems consisting both of encoders and decoders. How can decoders guarantee the encoder didn't use a certain technique? Additionally, there is one patent that I believe the encoder can avoid, but a standards compliant decoder wouldn't.

Someone who's even more familiar with the MP3 spec can probably confirm/deny/correct some of these.

Summary:
https://docs.google.com/spreadsheet/ccc?key...ZGxWeTlYUlpxS2c
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Prebsi
post Mar 28 2012, 17:35
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Avoiding 5559834 by commenting out the butterfly code is not just "odd" or "strange". The aliasing is really, really bad.

I've compressed a series of sweeps using a plain encoder and one that was hacked. This is the spectral representation of the two files.



No points for guessing which one is the hacked! Most of the time there are two tones instead of just one.

The amplitude is also all over the place compared to the original and I had to attenuate the file by 1.5 dB in order not to distort it too much on decode.

This post has been edited by Prebsi: Mar 28 2012, 17:49
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Posts in this topic
- bawjaws   working around MP3 patents   Mar 16 2012, 13:25
- - bawjaws   So, now you've got the general idea, some pate...   Mar 16 2012, 16:39
|- - saratoga   QUOTE (bawjaws @ Mar 16 2012, 10:39) Mayb...   Mar 16 2012, 19:12
|- - bawjaws   QUOTE (saratoga @ Mar 16 2012, 11:12) QUO...   Mar 19 2012, 16:24
|- - Garf   QUOTE (saratoga @ Mar 16 2012, 19:12) QUO...   Mar 19 2012, 19:57
- - ZinCh   this is US patents. is there any patents for MP3 i...   Mar 17 2012, 05:54
|- - bawjaws   QUOTE (ZinCh @ Mar 16 2012, 21:54) this i...   Mar 19 2012, 15:09
- - 2Bdecided   L3Enc was released in July 1994... http://en.wikip...   Mar 19 2012, 19:13
- - DVDdoug   If you try to get around the patents, but make som...   Mar 19 2012, 21:35
- - Garf   You certainly aren't going to make any patent ...   Mar 20 2012, 07:47
- - Garf   I found several other lists of patents, including ...   Mar 20 2012, 11:41
|- - .alexander.   Graf, if it's not too much of trouble could yo...   Mar 20 2012, 11:54
||- - Garf   QUOTE (.alexander. @ Mar 20 2012, 11:54) ...   Mar 20 2012, 13:04
||- - .alexander.   http://www.google.com/search?q=%22MPEG-2+A...tbo=1...   Mar 20 2012, 13:30
||- - Garf   QUOTE (.alexander. @ Mar 20 2012, 13:30) ...   Mar 20 2012, 14:14
||- - bawjaws   QUOTE (Garf @ Mar 20 2012, 06:14) I'v...   Mar 20 2012, 22:03
||- - Garf   QUOTE (bawjaws @ Mar 20 2012, 22:03) That...   Mar 21 2012, 11:49
||- - bawjaws   QUOTE (Garf @ Mar 21 2012, 03:49) I have ...   Mar 21 2012, 12:18
|||- - Garf   QUOTE (bawjaws @ Mar 21 2012, 12:18) So i...   Mar 21 2012, 13:24
||- - bawjaws   QUOTE (Garf @ Mar 21 2012, 03:49) QUOTE (...   Mar 21 2012, 13:59
||- - Garf   QUOTE (bawjaws @ Mar 21 2012, 13:59) when...   Mar 21 2012, 20:29
||- - bawjaws   Yeah, sorry, I meant comment out that If block, no...   Mar 23 2012, 21:22
|- - Prebsi   Avoiding 5559834 by commenting out the butterfly c...   Mar 28 2012, 17:35
|- - bawjaws   QUOTE (Prebsi @ Mar 28 2012, 09:35) Avoid...   Mar 30 2012, 17:00
|- - C.R.Helmrich   QUOTE (bawjaws @ Mar 30 2012, 18:00) I...   Mar 31 2012, 12:11
|- - Prebsi   QUOTE (bawjaws @ Mar 30 2012, 17:00) I...   Mar 31 2012, 16:29
- - polemon   I'd like to ask "how far we're into...   Mar 5 2014, 03:41
- - spoon   I believe they have expired pretty much in Germany...   Mar 5 2014, 10:19


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