[whatwg] MPEG-1 subset proposal for HTML5 video codec
Ian Fette (イアンフェッティ)
ifette at google.com
Fri May 29 07:37:53 PDT 2009
MPEG-1 is not exactly a popular codec on the web if you look at the
breakdown of video files on the web. The most popular formats are H.264 and
FLV. H.264 currently offers the best performance in terms of image quality
and compression (and is already the de-facto choice in a large, and
increasing, set of cameras / editing software / ...). I don't think we would
be interested in supporting something like MPEG-1 which is, at this point in
time, far behind the curve. We have chosen to support H.264 + AAC as well as
Ogg (Theora + Vorbis) for <video> in Google Chrome, mainly because H.264 is
what we see as the best performing option and Ogg is (currently) the most
viable open alternative. Encouraging everyone to use MPEG-1 would just
result in a lesser user experience and more bandwidth consumption, neither
of which really interest us.
2009/5/29 <jjcogliati-whatwg at yahoo.com>
> I propose that a MPEG-1 subset should be considered as the required
> codec for the HTML-5 video tag.
> == MPEG-1 Background ==
> MPEG-1 was published as the ISO standard ISO 11172 in August 1993. It
> is a widely used standard for audio and video compression. Both
> Windows Media and Apple Quicktime support playing MPEG-1 videos using
> Audio Layer 2. MPEG-1 provides three different audio layers. The
> simplest is Audio Layer 1 and the most complicated is Audio Layer 3,
> usually known as MP3. Since MPEG-1 includes MP3, a full implementation
> of a MPEG-1 decoder would not be royalty free until either all the
> essential MP3 patents expire, or a royalty free license is granted for
> all the essential MP3 patents.
> == MPEG-1 PRF ==
> I propose the following subset of MPEG-1 as the MPEG-1 Potentially
> royalty free subset (MPEG-1 PRF):
> MPEG-1 Video without:
> forward and backward prediction frames (B-frames)
> dc-pictures (D-frames)
> MPEG-1 Audio Layers 1 and 2 only (no Layer 3 audio)
> This subset eliminates the currently patented MP3 portion of the
> MPEG-1 Audio. It also eliminates the non-needed B-frames and D-frames
> because there is less prior art for them and this has the side effect
> of simplifying MPEG-1 PRF decoding.
> == Patents ==
> To the best of my knowledge, there are no essential patents on this
> MPEG-1 PRF subset. I have discussed this on a kuro5hin article, a
> post on the gstreamer mailing list and the MPEG-1 discussion page at
> Wikipedia, and no-one has been able to definitively list any patents on
> this subset.
> That said, "absence of evidence is not evidence of absence". There
> still may certainly be patents on MPEG-1 PRF. Next I will discuss
> some prior art that exists for this subset.
> == Prior Art for MPEG-1 PRF ==
> The H.261 (12/90) specification contains most of the elements that
> appear in MPEG-1 video with the exception of the B-Frames and
> D-frames. H.261 however only allows 352 x 288 and 176 x 144 sized
> video. H.261 is generally considered to be royalty free (such as by
> the OMS video project). There are no unexpired US patents listed for it on
> the ITU patent database.
> As for MPEG-1 Audio Layer 2, it is very close to MASCAM, which was
> described in "Low bit-rate coding of high-quality audio signals. An
> introduction to the MASCAM system" by G. Thiele, G. Stoll and M. Link,
> published in EBU Technical Review, no. 230, pp. 158-181, August 1988
> The Pseudo-QMF filter bank used by Layer 2 is similar to that
> described in H. J. Nussbaumer. "Pseudo-QMF Filter Bank", IBM technical
> disclosure bulletin., Vol 24. pp 3081-3087, November 1981.
> The MPEG-1 committee draft was publicly available as ISO CD 11172 by
> December 6, 1991. There is only a few year window for patents to have
> been filed before this counts as prior art, and not have expired.
> This list of prior art is by no means complete, in that there
> certainly could be patents that are essential for a MPEG-1 PRF
> implementation, but can not be invalided by this list of prior art.
> In the US, patents filed before 1995 last the longer of 20 years after
> they are filed or 17 years after they are granted. They also have to
> be filed within a year of the first publication of the method. This
> means that for US patents, most (that is all that took less than three
> years to be granted) patents that could apply to MPEG-1 will be
> expired by December 2012 (21 years after the committee draft was
> == Brief comparison to other video codecs ==
> Motion JPEG with PCM audio is the only codec that I know of that can
> be played in a stock Windows, Linux and Mac OS X setup. On the other
> hand, since it is basically a series of JPEG images and a 'WAV' file,
> the compression is much poorer than MPEG-1 PRF.
> Ogg Theora and Ogg Vorbis are newer standards than MPEG-1. My guess
> is that they can do substantially better at compression than MPEG-1.
> Assuming there are no submarine patents, I think the OGG codecs would
> be a better choice than MPEG-1. If you think that MPEG-1 PRF is not
> royalty free, but Ogg Theora and Ogg Vorbis are, you may find that
> comparing Theora to H.261 or Theora and Vorbis to MPEG-1 PRF is an
> enlightening exercise. Much of what is in MPEG-1 PRF is also in Ogg
> Theora and Ogg Vorbis.
> MPEG-2 is the next MPEG standard. It mainly adds error correction and
> interlacing. Neither of these features is particularly important for
> streaming video to computer monitors using a reliable data transport.
> MPEG-2 definitely is patented, and will be until at least the 2018
> time-frame. I don't think that this buys much over MPEG-1 PRF, and it
> definitely adds more patent issues.
> MPEG-4, H.264 have better codecs than MPEG-1, but these have a long
> time till the patents expire, so are unsuitable for use royalty free.
> == Remaining Work ==
> I am not a lawyer. In order to use MPEG-1 PRF, patent lawyers will
> have to investigate the patent issue and publicly report on the
> patent status. Unless there is a report sitting around that can be
> published, this will likely be expensive.
> As well, the prior art review is not complete. The biggest missing
> piece is synthesis window for the audio layer.
> It would be useful if there is any large company that uses MPEG-1 who
> does not have a MPEG-2 or MPEG-4 license. One possible example of
> this might be a software only video CD player.
> I created a wikia page to put up information on MPEG-1 status:
> == Satisfaction of requirements ==
> >From 18.104.22.168 HTML 5 draft:
> 1. does not require per-unit or per-distributor licensing
> Probably. There does not seem to be anyone requesting this kind of
> licensing right now.
> 2. Must be compatible with the open source development model.
> Probably. There does not seem to be any identified patents for MPEG-1 PRF.
> 3. Is of sufficient quality as to be usable
> Yes. Much better than the next best option of Motion JPEG. Probably
> worse than Ogg Theora or H.264.
> 4. Is not an additional submarine patent risk for large companies.
> Probably. It has been widely implemented (in DVD players, in Apple
> Quicktime and Microsoft Media Player) Note that these example uses
> have either a license for MPEG-2 or MPEG-4 however.
> == Conclusion ==
> The MPEG-1 PRF subset defined here seems to fit all the requirements
> of a codec for video for HTML5. It seems to be patent free. A final
> conclusion will depend on whether or not patent lawyers can sign off
> on this proposal and if the quality of MPEG-1 PRF is deemed
> == Disclaimers ==
> I am not a lawyer. These are my own views. I probably made
> mistakes. Please correct me where I am wrong.
> Josh Cogliati
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