[gentoo-user] Re: converting any video to mpeg-1, mpeg-4 or DivX-5

[James]

Iain Buchanan <iaindb <at> netspace.net.au> writes:


> I have lots of different types of video files - from short funny ads, to
> 1/2 hr tv episodes, to full movies, in all sorts of formats - wmv, avi,
> mpeg, etc.

yes we all suffer from numerous types of video. Often the differences
are trite, just enough to intice cosumers(microsoft victims) to
go out and spend money unnecessarily.

> I want to find a program (hopefully only 1!) that will help convert them
> to a format playable by the device.  I'm happy if thats a command line
> only program.  I will probably copy them 1 by 1 as I want to watch them.

yes well that's the dream we all share. Currently, it a work in progress
and to be robust, your going to use many different pieces of code.
When ffmpeg hits 1.0 your dream might be close....

> Space it not too much of an issue (I'll eventually have about 60Gb on
> the device) - I'd rather not lessen the quality any more than it is
> already.

Disc space is a relative thing. It always get's filled up. Human nature.
You will never have enough disk space for adults is like
candy for children, never, ever enough.


> So, here are my questions:
> 1. whats the best format to use out of the ones listed, given

Well you first have to realize that 'mpeg 4' is like saying
I want a car. It has numerous classifications and profiles that
allow a vendor to deliver 'mpeg 4' which is a virtual blend of mathematical
technologies that are slightly incompatible with other vendor's equipment
and software.

Take remote video surveillance.  'MPEG 4 ASP', is often referred to 
as the simple profile. The last time I look Mpeg4 has 18 visual object
types and 19 different visual profiles: Nine of the visual profiles are defined
my MPeg4 visual version one: simple, simple scalable, main, n-bit, core,
Scalable texture, basic animated texture, simple face animation and hybrid....
It goes on and on and on. In essence when a vendor tells you, it's
mpeg4 it may be interoperable mpeg4 based video and it may not be.
Enter REVERSE ENGINEERING.....

Good news. Mpeg4 porfile 10 AVC is the same as ISO's H.264, except for
some minor header differences. Currently. H.264 delivers the highest quality
for a given level of compression (that's the natural trade off for
all video and images, i.e. quality vs size. Human perception of quality
does not mimick mathematical measurements of quality, i.e. quality
as perceived by humans is subjective, interspersed with some established
proven techniques. That's why video is so complicated. The perception
 of quality is mostly subjective with some mathematical tendencies.

H.264 is the best (current consensus of experts) but, it is licensed and
owned by nefarious video moguls. Still there are filters in  the public
domain that allow for conversion (ffmpeg for one) others exist. H.264
which the same as 'mpeg4 part 10 AVC' is still a work in progress
as the various mathematical tools available are staggering. Kalman
filters is my favorite.... H.264 is CPU intensive, particularly
on the encoding side of compression.

However, there are those that believe 'theora' will be dominant or
dam close, in the not to distant future. MJpeg makes nice video streams,
but for broadcast in uses twice as much bandwidth to an equivalent
(remember based on subjective human evaluations) h.264 video stream.
This may not be a factor on a LAN, but it dominates WAN considerations.

>    a) Good quality (not much less than, or the same as original)

Use H.264 until theora matures.

>    b) Size reasonable - large files ok, but compression is always a
> bonus)

H.264

> 2. what program will convert 'anything' to said format.

Ah, well, being a computer scientist, I dabble in things that are,
incomplete. If/when you find a simple package to do robust video
manipulations of all sorts, do drop me a line. For now, plan
on using a palate of code and packages.

All things video are a work in progress. I can run (2) color
video streams over a 56 kbps frame relay link, with acceptable
quality for a utility. For their needs, nothing is close to
H.264, at this time, as we have evaluated dozens of formats.
H.264 is also the most efficient in raw video storage.  Still
I stuggle with a software package that will run on linux;
one day. H.264 is largely being ignored by the 'open source'
community, for obvious reason, but, it does yeild stunning
results.


HTH,
James






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