Brian J. Murrell wrote:
On Tue, Nov 20, 2001 at 08:54:45AM +0200, Justin Schoeman wrote:
The sort of jerkiness you are talking about is typically the result of 1
of 2 things:
1) Hard disk speed is too slow. To fix this, use hdparm to optimise your
drive settings, or use a compression algorithm with higher compression
ratios.
Well, if I were using an mpeg/divx/div4 bitrate of (say) 1800kbps that
is only 230,400 bytes/s required disk throughput. Even over NFS I can
achieve 6.7 megabytes/s:
$ time dd if=/dev/zero of=/video/test.avi bs=1024k count=100
100+0 records in
100+0 records out
0.00user 0.85system 0:14.82elapsed 5%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (144major+25minor)pagefaults 0swaps
[brian@pc NVrec-20011102]$ ls -l /video/test.avi
-rw-rw-r-- 1 brian brian 104857600 Nov 20 03:09
/video/test.avi
So disk can hardly be the issue right? Or is there something other
than raw throughput that I am missing?
No - this is more than fast enough.
You may notice that these two are contradictory - so you need a fast HDD
or a fast CPU, or preferably, both.
I think I have both. My CPU is an AMD Athlon-800 (Thunderbird).
I have an Athlon 600, and use DIVX4rec with the "-dq3" option.
I tried that just now. I am floored by the quality -- compared to
what I have been getting in the past. I like! I like! I am sure I
tried all of the XXXrec tools in the past and none were working all
that well. Hmmmm. You know now that I think of it, I think the
problem I had with the DIVX*rec tools was that the playback seemed to
"smear" with Mplayer. Any ideas on that? It seems alright now but if
it were to happen again it would help to know what to look for.
I am not sure what "smear" you are talking about... It could be
interlace problems, in which case using the "-deinterlace" option for
DIVX4rec should help.
It never
drops any frames,
I only got frame drops when I asked the computer to do something else
simultaneously. :-)
and the quality is still pretty good.
Indeed.
On a PIII-800,
I use "-dq 5", and the quality is awesome...)
I compared -dq 3 and -dq5 recording from analog cable and I don't
think I see much of a difference. I think to be sure I would need to
encode the same clip from cable twice so I could actually compare side
by side. Who cares though? -dq3 looks good. :-)
The quality setting really show when you lower the bitrate. Using "-dq
5", I drop the bitrate to 256kbit/s, and it still looks good (most of
the time).
mp1e is the best low-cpu option I
have ever seen,
Indeed!
but I have had many problems with A/V synch.
Me too! I guess we can just hope and wait for RTE to work with
RTErec.
Something I did notice in going back over the XXXrec tools: DIVX4rec
seems to have an A/V lag. The audio and video seem to be out
somewhere between a half a second to a second. Using DIVXrec seems to
be just fine however.
Aargghh.... This is the second time I have received a bug report along
these lines, but I have never managed to duplicate it! I use DIVX4rec
for day to day VCR usage, as well as continuous live streaming of TV,
and never notice any synch offsets (on any of the PCs I use). The last
bug report said that the AVI header may be wrong, but I am not clued up
enough on AVI to know what is wrong with it...
If anybody has any idea what the problem could be please let me know!
8-)
-justin
