[MPlayer-users] Preserve interlacing; prevent tearing on TV-out?

Arpi arpi at thot.banki.hu
Sat Oct 20 15:46:30 CEST 2001


> FYI, I've read the fine manual, and I think MPlayer is a fine program. 
> Thank you for your good work.
> I don't know much about video, but it's become important to me recently
> and I'm learning quickly, so please be patient.
> I have captured an NTSC source and compressed it using Divx4.  I am
> playing it back now (using MPlayer) on a computer with a standard VGA
> card connected to an external scan converter (VGA->NTSC).  The video
> looks good to my uneducated eye but for two problems: interlacing
> artifacts and tearing.
> I considered deinterlacing the source before compressing it, but
> rejected that idea because deinterlacing is a lossy process and I want
deinterlacing is not so lossy as compressing interlaced pictures with
an algo not designed for this.
mpeg2 does support interlaced source - it has special thing called
interlaced DCT. ms-mpeg4 (divx) doesn't support this, as it uses h263

so, use mpeg2 or deinterlace first.
btw deinterlace is not lossy at all, if you do it well.

hint: double framerate and half vertical resolution - i mean
split frames to fields.

> to keep the quality high.  I intend to view the video on a television
> anyway, which is interlaced.  For a recommendation of interlaced MPEG4,
> see http://people.freenet.de/codecpage/mjpegtst.html#Anker55473.
msmpeg4 != iso mpeg4

> I understand that the interlacing artifacts are there because VGA output
> is progressive (non-interlaced).  The tearing, I imagine, is being
> caused by playback at a rate not synchronized with the 29.97 fps of the
> video file as well as the output device (television).
yes it's possible.

> How best to solve these two problems?  My guess would be a new video
> card with a TV-out port, eliminating the need for the scan converter.  I
> would configure X (or some other video output device) with a modeline
> that corresponds to NTSC (29.97 fps, interlaced).  The software (in this
> case MPlayer) would see an interlaced frame buffer in the output device
> (?), see that the video file is interlaced, and Do The Right Thing (?). 
mplayer has no special code for this. btw it should work without it.

if quality really matters - buy a hardware mpeg decoder card wiht tvout.

> Or maybe it wouldn't, but the Right Thing would happen anyway?  This

> To solve the tearing, I would configure the video output device such
> that its vertical sync (?) is locked with the vertical sync on the
> TV-out port.  Would this work?
tvout is synced to video device. not reverse.

> If the solution is to buy a new VGA card with TV-out port, then which
> one should I buy?  I know the developers here have done a lot of work
> with the G400, but it's not a good candidate for a newcomer because it's
> no longer being sold.  The Voodoo3's TV-out can be controlled on Linux
> using lm_sensors, but it's also no longer being sold.  ATI won't release
> support for TV-out in Linux because of Macrovision concerns.  nVidia
what about old ati cards? they are still sold.. mach64 and rage128 cards.
btw i never tried their tvout, but gatos supports them.
(i have such card at work - but no tv there)

A'rpi / Astral & ESP-team

mailto:arpi at thot.banki.hu

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