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jgaz
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Joined: 14 Feb 2021
Posts: 42

PostPosted: Thu Dec 30, 2021 12:35 am    Post subject: Meticulous DVD content preservation questions Reply with quote

I'm trying to preserve DVD's in my collection somewhat meticulously. My goal is to preserve as much information as possible from the original DVD but make it relatively easy to transcode on the fly and stream the contents to other devices on my network. Right now, I'm using mplayer to dump DVD's to a single VOB. It's simple and it works just fine 99% of the time. Where things break down are around closed captioning information and/or subtitles.

What I am envisioning is something like this:

* An MKV container.
* The original video stream.
* The original audio stream(s) separated out by language.
* Chapter information. (I'm not sure how to capture the timings, but I can get the chapter titles from the DVD scene previews).
* Subtitles (with fallback to CC that has been if absolutely needed) encoded as text.
* Optional extra meta-data such as DVD covers, cast info, etc.

I realize that closed captions are basically bitmapped graphics encoded as ancillary data in the video signal. It looks like at least some DVD's bitmapped tiles for text instead of an actual character encoding that can easily be converted to UFT-8.

I'm stuck on a few points:

DVD dumping is working as follows:

Code:

mplayer dvd:// -dumpstream -dumpfile file.vob


That gets me the initial dump. How do I separate out the video and audio streams? (Stop me if this is a bad idea, even with an MKV container).

Any thoughts on how to get the chapter timing?

What's the best way to extract subtitle information and have it "just work"? Before anyone recommends HandBrake, I've run into subtitle extraction bugs, so I want to do this a bit more manually.

I'll save my questions regarding setting up a streaming media server for when I get that far. Is anyone else doing stuff like this?
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pa4wdh
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Joined: 16 Dec 2005
Posts: 806

PostPosted: Thu Dec 30, 2021 12:01 pm    Post subject: Reply with quote

I realize this isn't really an answer to your questions, but regarding backing up DVD's i'm using dvdbackup and dd to get an actual ISO file from the dvd. The ISO still has all encryption etc. in it, so i guess the procedure is legal. The big plus in this method is that the ISO's can be played with any media player that supports playing DVD's.

The process has two steps:
- First use dvdbackup (provided by media-video/dvdbackup) to get the DVD drive to be able to read the DVD.
- When that's done simply dd from the DVD drive to a file, and there's your ISO.

So:
DVD=/dev/sr0
dvdbackup -I -i $DVD
dd if=$DVD of=dvd.iso bs=1024k
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Jaglover
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Joined: 29 May 2005
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Location: Saint Amant, Acadiana

PostPosted: Thu Dec 30, 2021 2:38 pm    Post subject: Reply with quote

ddrescue is better suited for this task than dd.

There are many applications for managing tracks and re-muxing. Mkvtoolnix, Avidemux to name a few. Getting bitmap subtitles into text is always a challenge, Gaupol (subtitle editor) is capable to correct OCR errors, but the final touch is by hand ...
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Hu
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Joined: 06 Mar 2007
Posts: 21431

PostPosted: Thu Dec 30, 2021 4:38 pm    Post subject: Reply with quote

Due to the obnoxious legal restrictions around the anti-copying technology that impairs most (or all?) commercially sold DVDs, you may not get much support here. As I understand it, US law on the subject says that circumventing a measure that was intended to impair access is copyright infringement, even if done for an otherwise legal purpose (such as making a private backup), and even if the measure intended to impair access is laughably easy to defeat. As such, discussion of techniques to bypass such measures is discouraged.

If the DVDs were sold "in the clear" such that you could just stick them in a DVD drive, mount the filesystem, and look around, this would be easy - and the distributors would lose their minds over how easily DVDs could be copied and redistributed.
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Jaglover
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Joined: 29 May 2005
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Location: Saint Amant, Acadiana

PostPosted: Thu Dec 30, 2021 5:12 pm    Post subject: Reply with quote

What Hu said is true, however, there is media-video/makemkv in portage, methinks using it is legal in some countries.
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