On Tue, 7 Sep 2004, Norayr Chilingaryan wrote:
> I have to say, that mpeg2enc is the best mpeg coder I ever seen.
There are better ones but they cost $$$ ;)
> As You know, dc10plus can capture 768x576 or 384x288 videos, i. e. exactly
> 4:3 aspect.
That is because the dc10+ is sampling the signal at the square (1:1)
pixel frequency.
> It is fine, and when converting videos to mpeg I use '--no-constraints'
> parametr and then view videos with computer.
You should _never_ use --no-constraints unless you know exactly what
you are doing. The constraints are there for a reason (to make sure
the generated output is within specifications). mpeg2enc was probably
complaining about the fact that you were using an invalid frame size
(768x576 with 1:1 pixels).
> But as I understand, now in the output file I have another aspect ratio,
> so video is a little deformed...
Correct. It sounds like you are in a country that uses the 625 line
(often called "PAL") video standards. For that video system the normal
sample (pixel) aspect ratio is 59:54
> I remember in TMPEGEnc there is a feature, that can add black strips on
> the top and bottom of the screen and leaves video with same aspect ratio
> How it is possible to do with mjpegtools ?
You do not need or want to put black bars on. All you need to do
is resample (scale) the data to the correct SAR (Sample Aspect Ratio).
To do that you want 'y4mscaler':
http://www.mir.com/DMG/Software/y4mscaler.html
if you are using the cvs version of mjpegtools you need y4mscaler
0.7.1. if you are using the 1.6.2 release of mjpegtools you need
y4mscaler 0.6.2
Then for 768x576 input you would add:
... | y4mscaler -I sar=1:1 -O sar=PAL -O size=720x576 -S option=sinc:4 | ...
immediately before the mpeg2enc program
If you do the arithmetic you will see that 768 square pixels is
exactly the same as 720 59:54 pixels.
For 384x288 (which I think is single field only and not interlaced)
something like this might work (but I have not tested it):
...| y4mscaler -I ilace=NONE -I sar=1:1 -O sar=PAL -O preset=352x288 -S option=sinc:4
| ...
That works because 384 1:1 pixels is equivalent to 352 59:54 pixels.
Good Luck!
Cheers,
Steven Schultz
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