[linux-dvb] Re: transcoding to SVCD and VCD

[Peter Hofmann <junk@pxh.de>]

Hi,

On May 2, 23:25, Andreas Berger wrote:
> Subject: [linux-dvb] transcoding to SVCD and VCD
> For the SVCD transcoding, mpeg2enc gives for the parameter -F:
>
>  -F num     only for MPEG 2 output:
>                0 = progressive output (no field pictures)
>                1 = field pictures, bottom field first
>                2 = field pictures, top field first
>                3 = progressive output, field MC and MDCT
>
> the script uses -F 3, progressive output. Does this make sense? Should I
> use 1 or 2 instead (and if - which one?)
as subject.
>-- End of excerpt from Andreas Berger

I think the mpeg2enc README gives incomplete information. Here are some
excerpts from the mjpeg HOWTO:

"-F 3 tell mpeg2enc to assume that the original signal is field interlaced
video where the odd rows of pixels are sampled a half frame interval after the
even ones in each frame.
The -F 0 (progressive output (no field pictures)) option will also work for
PAL.
-F 1 and -F 2 will work but are currently handicapped by rather dumb code to
choose the type of motion compensation."

The MPEG stream from the DVB card will have interlaced video (= field
pictures). So you must choose the -F 3 option to let the encoder compensate for
this.

The output of the encoding process is then progressive, i.e. non-interlaced.
This is very good for playback on your PC, because the VGA graphics card
outputs progressively.

A standalone DVD/SVCD player will reconvert the video to interlaced - as is
normal for playback of movie DVDs, which are also encoded in progressive mode.

(BTW new (and expensive) DVD players are able to play back NTSC (but currently
not PAL because of copyright protection issues) via the component output. You
will only benefit from that if you have a video projector, however.)

Peter

-- 
Peter Hofmann                  e-mail: junk@pxh.de


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