Progressive scan video and panasonic mpeg encoder
Bob Curnow
In the settings in panasonic mpeg encoder, there is an option to choose
odd or even fields as opposed to both. If my dv video is progressive
scan, would it matter if I selected odd or even? My reasoning is that
if I selected odd or even, the encoder would not have to encode as many
fields, thus increasing video quality.
Thanks,
Bob C
Jukka Aho
news:390D19FE...@sonnet.com...
> In the settings in panasonic mpeg encoder, there is an option to
> choose odd or even fields as opposed to both. If my dv video is
> progressive scan, would it matter if I selected odd or even?
No. But with progressive source material, you should be encoding
both fields, anyway.
> My reasoning is that if I selected odd or even, the encoder
> would not have to encode as many fields, thus increasing
> video quality.
No, it does not work this way. Your DV video is originally
either 720x576 (PAL) or 720x480 (NTSC). In order to store
it in VCD compliant format, the Panasonic MPEG-1 Encoder
has to scale the source material to 352x288 (PAL) or
352x480 (NTSC) before offering to the actual encoder
part.
Now, the scaling can be done in many ways. If you choose
to deinterlace by discarding odd or even fields, it will
do the vertical scaling by simply throwing away every
other line. But there is no need to deinterlace, as your
footage wasn't interlaced in the first place.
Throwing away information is not good at all - you will get
better results when you choose both fields (and high quality
resampling) as the program will then interpolate the odd and
even lines together, retaining all the informationg there
was to be extracted from the original image.
Video resolution is a complicated issue. Suggested reading:
<http://www.elitevideo.com/new2.htm>
<http://www.microsoft.com/hwdev/TVBROADCAST/ovrsamp.htm>
<http://www.microsoft.com/hwdev/TVBROADCAST/convrg1.htm>
In short, by using both fields you will get the oversampling
benefits and also avoid unnecessary aliasing artifacts.
Note that as youre using 720 pixels wide source, you should
also crop 8 pixels from the left and right side of the original
image before scaling to 352 pixels wide image. Otherwise,
the aspect ratio will be slightly off. (Simply use Panasonic's
"Crop Processing" function - put the mark to "Cut image" and
adjust left and right border by 8 pixels each.)
-- znark