Date: Thu, 14 Mar 1996 19:50:01 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: multimedia@freebsd.org Subject: mpeg and related stuff Message-ID: <199603141850.TAA25197@labinfo.iet.unipi.it>
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Some info on the current status of video-related stuff, in case
someone is interested.
METEOR
------
Jim Lowe released version 1.0.10 of the driver about 10 days ago.
Among other enhancements, it fixes the problem with VCR input when
used with "nv" or "vic". For those interested in fixing previous
drivers, the problem was caused by a missing tilde:
case METEORSTATUS: /* get 7196 status */
temp = 0;
SAA7196_WRITE(mtr, 0x0d, SAA7196_REG(mtr, 0x0d) | 0x02);
SAA7196_READ(mtr);
temp |= ((*((volatile u_long *)mtr->stat_reg)) &
0xff000000L) >> 24;
SAA7196_WRITE(mtr, 0x0d, SAA7196_REG(mtr, 0x0d) & ~0x02);
^
|
---- this one was missing -----------------------------------+
SAA7196_READ(mtr);
I guess it took quite some time to figure it out!
Unfortunately, version 1.0.10 has a bug (at least for me, in PAL
mode) in that single-field operation is not working anymore (you
always get both fields). I spent almost a couple of hours looking
at the sources and diffs with previous versions without coming up
with a solution. So, at the moment I am running 1.0.9
I have discussed with Jim about the possibility of adding a timecode
next to each frame, so that it's easier to do some post-processing of
the data in case they are dumped to disk or whatever. Hopefully this
will be present in the next releases.
TV program
----------
Don't know if there is a "current" version of the program, as I
did not use it for a month or so. I did some changes to my own
version and I can now save full sequences to disk, or get input
from a file instead of the meteor board. The first option is useful
both for producing input data for subsequent compression, or,
together with the second option, to build a disk-based VCR. With
my IDE disk running at over 5MB/s, I can almost save live video to
disk. The code needs to be cleaned up a little bit, but apart from
this it is mostly working.
I believe "tv" ought to become part of the standard releases of
FreeBSD.
----- Berkeley Multimedia Tools (bmt1r2.tar.gz) --------
MPEG_ENCODE
-----------
I succeeded in compiling the mpeg_encode stuff from berkeley. It
compiles pretty much out of the box.
In order to do mpeg compression on sequences captured on the "meteor",
I had to build a converter from rgb15 to the YUV4:1:1 format. Other
than that, it works reasonably well. When time-codes will be supported,
it will also become possible to set the frame-rate in a more controlled
way.
MPEG_PLAY
---------
This one requires some fixes to work with different screen depths (15
bit, as an example), similarly to what was done with the mpeg_play in
-ports. This would be really usefuf, as the newer mpeg_play has more
options and gives you more control over the output.
AVI ETC.
-------
So far I have not found any compression tool Xanim works for playing
the files.
XANIM
-----
While Xanim can play most of current video formats, I suspect it
can only play I-frames, and simply discards B- and P- frames, so
that the output looks more like a slide show than a real movie (as
with mpeg_play).
Luigi
====================================================================
Luigi Rizzo Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it Universita' di Pisa
tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522 http://www.iet.unipi.it/~luigi/
====================================================================
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