[MPlayer-users] Re: recording from video tapes (a novice question)

Stefan Seyfried seife at gmane0305.slipkontur.de
Tue Aug 12 09:30:49 CEST 2003

jsbien at mimuw.edu.pl writes:

> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]

>>or your mixer settings are too low or muted. 
> I hear the sound while recoding. Is it the expected behaviour of mencoder?
> The volume of the sound I hear while recording is sensitive to the
> volume and line settings in xaumixer. However, the settings have no
> effect on recording.

Hearing sound when watching tv has not much to do with recording sound.
On most soundcards, there is an extra mixer channel "Igain" which controls
the recording volume and is normally has nothing to do with the "Line in"
volume setting.
BUT you have to tell your soundcard, which channel it should record.
I use "aumix" for this (console mixer app), select my Line in-Channel with
the cursor-up-down-keys and press "space" to turn on recording this channel.
You can qery your settings with "aumix -q":

seife at mixi:~> aumix -q
vol 100, 100
pcm 50, 50
speaker 0, 0
mic 36, 36, P
mix 0, 0, P
igain 48, 48
line1 64, 64, R
line2 0, 0
line3 0, 0, P

this tells us that line1 is recording, igain is at about 1/2.

To test this settings, i use the "record" tool from kraxels xawtv package
(under SuSE it is in package v4l-tools), which has a nice level meter in
the console to check for overdriving the soundcard.
One thing i have noticed is that many crappy soundcards (Creative SB128
pci...) in fact only have a 15bit a/d-Range and give real heavy
distortions when recording to levels above ~half (16384), so i keep my
recording levels lower than about half VU, when recording VHS or from TV
it doesnt matter anyway.

> The strange thing is that the results of my experiments are not fully
> consistent. Unfortunately, my experiments are rather chaotic as I
> switch between xawtv, zapping and mplayer/mecoder. Perhaps the
> settings in one program are inherited by others? There was a session

well, xawtv and mplayer dont touch the mixer AFAIK, so they inherei
the current settings.

> capture card is AverTV Studio 203.

i record succesfully with an avertv card (dont know which one).

> Any new suggestions?

When recording video i noticed, that capture devices are very sensitive
to tape jitters or badly adjusted video heads. They just drop frames, even
if you can watch the tape on an tv set without noticing picture problems.
This happens often when playing a tape on another video deck than the one
it was recorded on. Sometimes the tracking adjustment can help (slightly
de-adjusting from "optimal" setting), sometimes it can't.

 Stefan Seyfried, seife at gmane0305.slipkontur.de

Good, Fast, Cheap: Pick any two (you can't have all three). RFC 1925

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