[vorbis] Re: [livid-ovd] putting the video into ogg multimedia

[Robert Scott Horning]

Ralph Giles wrote:

> With both vorbis and libmng nearing stable status, I've been thinking
> about combining the two to make a real multimedia format. What would be
> involved in embedding mng in an ogg bitstream? From what I've read of the
> documentation, there doesn't seem to be any codec-enumeration system. Do
> we just interleave the packets and let the player guess based on the
> headers which codec to try? I suppose that works so long as the spec for
> the multimedia files has a well-defined list of what is to be supported.
>
> Practical motivation:
>
> MNG is open, free, unencumbered and seems to have a clue in terms of
> well designedness so it's a good match. While it doesn't provide
> high compression ratios for video sources, it supports both completely
> lossless and motion-jpeg encoding. In my mind that makes it an excellent
> source or editing format for digital video. This would probably also
> require an option for uncompressed audio; I suppose the pcm .wav header
> could be abused for this purpose.
>
> MNG was also designed as an animation format and should achieve good
> compression of both traditional (2D) animation and "talking-head" video
> where localized motion occurs over a static background. I think there's a
> lot of room here for creatively-lossy compression research, some of
> which might be applicable to the free video codec.
>
> Finally, I agree with DVD-video's use of graphic overlays for subtitling
> (though the text should also be available in a separate stream) most
> particularly for the annotative possibilities. So even when there is an
> Ogg video codec, I'd still like to see support for transparent mng
> overlays.
>
> Tying all this together seems to require some stream-description metadata.
> I guess that's another way to handle codec identification. How's work on
> that progressing? I see a need for (multiple) text/xml streams for
> lyrics/subtitling/commentary in both the audio and video formats as
> well, which should probably be separate from the meta-data.
>
> In short, I feel the combination of mng and vorbis would go a long way
> towards a useful multimedia format in the near term, even without a
> vorbis-comparable video codec.
>
> Comments please,
>
>  -ralph

I will say that I am fully supportive of using MNG for a multi-media file
format.  The PNG chunk system is VERY extensible and you can even throw in Ogg
data or even MPEG (if you weren't worried about patent issues).  The audio
data is not nearly so well defined, but there are plenty of formats available
for that, and to start with you could do some low quality PCM data and be just
fine with MNG.

Doing some subtitles with an alpha blended PNG frame would look neat too, and
would have a much better effect than some of the choppy asian characters that
I've seen with sub-titled DVD discs.  (Some of the 20+ stroke characters look
like a little white blob.  I don't really read chinese, and I'm kinda curious
what a native speaker tries to make of those characters when they appear.)

<RANT>

I personally favor the MNG approach over the Ogg strategy because of the way
the licensing agreements read.  Ogg is more like "you are free to use this,
just don't change it without our permission" as opposed to MNG which is simply
an open specification.  In other words, I would be much happier with OggVorbis
if they had a slightly different license agreement.

However, I will take that license any day over the DVD Forum NDA.   Heck, I'd
rather sign an NDA with Microsoft for that matter. :)

</RANT>


--
Robert Scott Horning
Trans-Lux West
1651 North 1000 West
Logan, Utah  84321
Phone: (435) 716-8696
FAX: (435) 752-8513
E-mail:  roberth at ise-tlx.com

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