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