[Cin] Old page on DVD creation under Linux (2005)

Phyllis Smith phylsmith2017 at gmail.com
Tue May 30 17:03:25 CEST 2023

Like the line in one of the URLs that reads "and why interlacing should be
abandoned asap".

On Tue, May 30, 2023 at 3:21 AM Andrew Randrianasulu via Cin <
cin at lists.cinelerra-gg.org> wrote:

> https://www.qsl.net/n1gg/linux/video/linuxdvdguide.html#6
> =====
> ------------------------------
> Chapter 6: Subtitling Subtitling is an integral part of many DVD
> productions. Although I personally have used subtitles very rarely, this
> guide would not be complete without some information about subtitles.
> Many times it is necessary to subtitle video if the audio language needed
> is not available, or for the hearing impaired, or to add commentary. The
> DVD specification allows for a very nice subtitling method. Instead of
> having to render the text on the video itself (which would mean you could
> not turn the subtitling off), DVD implements subtitling as a series of
> images overlayed on top of the video. This way, you can switch between
> multiple subtitle tracks, or turn them off altogether. Although this takes
> up more data space than plain text subtitles, it is far more versatile: the
> fact that images are used makes it possible to subtitle using any font and
> even nonstandard characters and images.
> 6.1 DVD Subtitle Format The DVD subtitle specification allows for 4-color
> images with a transparent background. They can be created in nearly any
> format, but must be converted to the special DVD compliant stream before
> they can be put into the DVD structure.
> 6.2 Subtitling MPEG Streams For DVD Using Spumux Spumux is one such tool
> to create DVD subtitle streams. Although there are many tools for
> subtitling, Spumux is very useful in many areas and I have experience with
> it.
> It accepts several image formats, including PNG, which I find to be the
> most beneficial format (not just for DVD operations but for many other
> things as well).
> First you must create your text images. You may do this with your favorite
> image editor (IMHO, if you have a brain, it's Gimp), or you may use a
> text-to-image tool to make the images from your plain text such as Fly
> (which i will not cover here). Spumux will also accept subtitles in a
> number of text formats. See the manpage for a list of them. Since using
> spumux with text files can be extremely complicated, and there are multiple
> options for file formats, etc., I will only cover using PNG images for
> subtitling here.
> So open Gimp, (or whatever image creator that suits your fancy), and
> create a new image with a transparent background. Actually you may have a
> colored background if you like, but bear in mind that this may distract
> from your video. Sometimes this is necessary, such as if you have white
> text on a white-dominated video scene (such as snow), but most of the time
> this is distracting and looks cheap. Choose a color for your text. I have
> found that most of the time the best color for subtitle text is a light
> gray or white. Then use the text tool to create your subtitle text, and
> slap it onto the background. Be sure that you do not use more than 4 colors
> in your image, as spumux will reject the file if it has more. The DVD
> specification only allows for any 4 colors in a particular subtitle stream
> If you did use more than 4 colors, such as for a fancy gradient text or
> something, or possibly if you used anti-aliased fonts, you may set the
> image type to indexed, and dither the image down to 4 colors. In Gimp,
> right-click on the image, go to the "Image" sub-menu, the "Mode"
> sub-sub-menu, and select "Indexed...". Optionally, you may get to this
> dialog using the keyboard by pressing "ALT+I". Then make sure that the
> "Generate Optimal Palette:" option is checked, and set the number of colors
> to 3 or 4. Then save the image as PNG.
> It is interesting to note that since the DVD subtitle method is to use
> images, you may put, well, images into the subtitle stream, and they will
> display just like text. Of course you are still limited to 4 colors, but
> this comes in extremely handy for foreign language subtitles, and when you
> need special fonts and text styles.
> ===
> Interesting info!
> Also, there was another page suggesting yuv420 option useful for *NTSC*
> interlaced DV to DVD
> https://renomath.org/video/linux/dv/encdvd.html
> ====
> Our focus is encoding widescreen NTSC interlaced video source from a
> miniDV camcorder. We attempt to preserve as much of the quality of the
> original source as possible.
> [..]
> Mjpegtools The mjpegtools encoder runs more slowly than ffmpeg on my
> computer; however, no patches are needed to handle interlaced video. The
> encoding commands
> $ lav2yuv s001.avi |
>     yuvcorrect -T INTERLACED_BOTTOM_FIRST |
>     mpeg2enc -M0 -nn -a3 -f8 -G18 -b7000 -V230 -q9 -o s001.m2v
> $ lav2wav s001.avi > s001.wav
> $ toolame -b224 -s48 s001.wav s001.m2a
> $ mplex -f8 s001.m2v s001.m2a -o s001.mpg
> work, but unfortunately reduce the effective color space to 4:1:0. Better
> results can be obtained by using y4mscaler and the commands
> $ lav2yuv s001.avi -C 411 |
>     y4mscaler -I ilace=BOTTOM_FIRST -O chromass=420mpeg2 |
>     mpeg2enc -M0 -nn -a3 -f8 -G18 -b7000 -V230 -q9 -o s001.m2v
> $ lav2wav s001.avi > s001.wav
> $ toolame -b224 -s48 s001.wav s001.m2a
> $ mplex -f8 s001.m2v s001.m2a -o s001.mpg
> This interpolates the chroma in the horizontal direction before
> subsampling it vertically.
> ====
> Yet another source suggest only old CRT TV
> can display interlaced DVD material as intended, and Plasma/TFT
> TV or computer monitors better accept de-interlaced material.
> https://xpt.sourceforge.net/techdocs/media/video/dvdvcd/dv04-Interlace/single/
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
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