[MPlayer-users] mencoder usage help

[P. Rybin]

On Jun 28 2002, Steven Adeff wrote:

> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hi, I tried making a Divx video today with the command line you gave
> me(except I enabled the audio to be encoded with lamemp3). couple
> questions, because the output video quality was quite poor...
> 
> 1. the mpeg source is interlaced, is there a setting i need to use to
> take this into account?

Yes, mplayer and mencoder support deinterlacing in two ways - blend and 
interpolate, you need to use the -npp switch with lb argument if you want 
linear blending, and ci if you want cubic interpolation. So the arguments 
to mencoder should be -npp lb or -npp ci You have to decide yourself on 
which yields the better result. And check the docs if you want more 
details.

> 
> 2. the output divx file looked compressed. the original is 480x480 and
> when i play it back in mplayer i get the line 
> 
> VO: [xv] 480x480 => 640x480 Planar YV12
> 
> but when encoding I get this
> 
> VDec: vo config request - 480 x 480 (preferred csp: Mpeg PES)
> Couldn't find matching colorspace - retrying with -vop scale...
> Opening video filter: [scale]
> Sorry, selected video_out device is incompatible with this codec.
> VDecoder init failed :(
> 
> which I don't understand at all...

MPEG files have an aspect ratio setting, so they can be scaled to the right 
size while playing. AVI does not have this feature, so when you encode, you 
need to rescale the video. This can be done in both mplayer and mencoder 
using the video out filters, the filter you need is scale: -vop 
scale=640:480 (Again, for more details, read the docs.)

> 3. there was lots of artifacting of the output divx file that got
> created, what other settings can i try to increase the quality(or is the
> only real way to increase the bitrate?

The artifact you're talking about are probably entirely due to the lack of 
deinterlacing. However, since you seem to be encoding a (S)VCD, the result 
will not be great, even if done well (since you encode a fairly 
poor-quality source in a lossy format into another lossy format).

> 
> thanks!
Hope this helps...

Pav