[whatwg] MPEG-1 subset proposal for HTML5 video codec

[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.

http://www.kuro5hin.org/story/2008/7/18/232618/312
http://sourceforge.net/mailarchive/message.php?msg_id=257198.16969.qm%40web62405.mail.re1.yahoo.com
http://en.wikipedia.org/wiki/Talk:MPEG-1#Can_MPEG-1_be_used_without_Licensing_Fees.3F

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.

http://www.itu.int/rec/T-REC-H.261
http://www.itu.int/ipr/IPRSearch.aspx?iprtype=PS
http://blogs.sun.com/openmediacommons/entry/oms_video_a_project_of

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
published.). 


== 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:
http://scratchpad.wikia.com/wiki/MPEG_patent_status    

== Satisfaction of requirements ==

>From 4.8.7.1 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
sufficient.

== Disclaimers ==

I am not a lawyer.  These are my own views.  I probably made
mistakes. Please correct me where I am wrong.

Josh Cogliati
http://jjc.freeshell.org/