[MPlayer-users] Tips on TV-encoding performance

[Steffen Barszus]

Am Sonntag, 10. August 2003 11:29 schrieb rcooley:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> I've been using mencoder on my system to record to MPEG4 in realtime
> from my TV-tuner card, but it uses up just about all of my CPU power, so
> I'm unable to do anything else with the system without dropping frames.
>   I really need to be able to playback on this sytem at the same time I
> am encoding.  If anyone has even the most trivial suggestion to improve
> performance, I'd like to hear it.
>
> But first, I'll cover a few things I've already tried, and their
> results, maybe someone can find where I went wrong.
>
> Here is the command-line I currently use:
>
> nice -n -19 mencoder -nocache -tv
> on:driver=v4l:device=/dev/video0:input=0:norm=NTSC:chanlist=us-cable:width=
>720:height=480:audiorate=24000:amode=0:outfmt=yuy2:channel="$CH" -vop
> crop=640:472:40:4,pp=md -ovc lavc -lavcopts
> vcodec=mpeg4:vbitrate=1000:vqcomp=0.0:vhq -oac mp3lame -lameopts
> cbr:br=48:mode=3

> Here is all the information about my system:
>
>
>    Mencoder command-line above.
>
> BTTV Module Options:
> options bttv card=78 tuner=2 radio=1 pll=1 autoload=1 fieldnr=1 gbuffers=32
> options tuner type=2
> options i2c scan=1 verbose=1 i2c_debug=0
>
> hdparm args:  -A1 -a64 -c1 -d1 -m16 -p4 -S240 -X66 -Xmdma2
> OS: Gentoo 1.4rc1
> All software compiled with "-march=athlon-xp"
>
> Actual Hardware:
>
>    AMD Athlon XP 2000+  1.666GHz Processor
>    Asus A7S333 Mobo
>    256MB PC2700 DDR RAM
>    Western Digital 40GB HDD, 7200RPM, 2MB Cache
>    KWORLD TV878RF-PRO BTTV Tuner Card
>

Without being an expert i would say your hardware is really enough to do what 
you want. I have seen a slower machine (Athlon TB 1333) capturing fullscreen 
(720x576) mpeg4 and mp3. What you could try is to take a higher bitrate for 
video, at least that helped a friend of mine. What belongs to the dropping of 
audio I really don't know whats going on. On the above setup we tried to 
capture using uncompressed audio and after a fixed time mencoder started to 
drop audioframes, recompiling and using mp3lame he can record some hours. On 
another machine even mp3lame has the same symptoms, alltough neither the 
hd-load nor the cpu-load justifies it. Maybe mencoder has a problem here ? 
Since I have a digital tv card i'm not that familiar with all that ....

Steffen