In ripping my mass library of DVDs, I run into all kinds of problems I never would have expected. I’ve been mentally keeping notes about them, and how to workaround them, but I should probably document the findings and process as well. The first one I want to touch on is poor authoring of chapters and their start times.
Here’s what happens. On a normal, full-length thirty or sixty minute (usually about 22 and 48 minutes, respectively) episode, there will be one track per episode on the DVD. Then, for each track, there will be chapters during major scene breaks, usually when the show would pause for a commercial break.
There can be a variety of problems though. Here’s the cases I’ve run into so far with tracks + chapter support:
- Wrong chapter start time
- No chapters at all
- Trailing chapters
The first one, wrong chapter times, becomes an issue on certain TV shows where there is an introductory preview to the show itself. This is very common on Universal Studios’ TV shows. Murder, She Wrote, Knight Rider and The A-Team will all have an introductory segment at the start of the show pitching what’s about to happen. I prefer watching a show blind, or not knowing what’s going to happen, so when ripping them, I can save a marginal amount of space (about 5%) by skipping over the summaries. Generally speaking, the chapters are authored correctly, so with mplayer, you start at chapter 2 and dump the stream or rip from that starting point. I’ve already setup my web interface for dvd::bend to specify a starting chapter that can either be set on a series or individual track.
That’s not always the case though — there are some DVDs where the authoring is broken. There will be an introductory scene like always, but the first chapter doesn’t end until the first commercial break. So skipping the first chapter also skips a chunk of the beginning of the story. That’s a bit of a problem.
The only solution I can come up with is pretty tedious — finding the correct starting position, putting it in the database, and tell MPlayer to start ripping from there. Unfortunately, this becomes pretty laborious because only some of the tracks are messed up, meaning you have to go through each track one by one to see which are correct and which aren’t. The upside to all of this is that it’s something you only do once.
One other idea I have, that I haven’t researched yet, is that the time duration from the beginning to the first commercial break are probably going to be about the same, and so I could insert my own chapter break. I’m basing that theory on the fact that the time lengths on each episode are all within a few seconds of each other. Obviously strict timing is a key element, for commercials. The idea needs some looking into, since there are two scenarios for intro scenes plus broken chapters: a summary intro or a show intro, plus the broken chapter ending. The second one would be consistent across the board, while the first I’d just have to find an average, and then calculate whether the next chapter break is so far back that it warrants inserting a fix.
That fix is also somewhat related to the second problem, of not having any chapters at all. Generally speaking, the only chapter I care about the most is when I can skip unwanted content, which is usually just the introduction. Not having any chapters usually happens on a per box set basis. I know that some Warner Bros. cartoons do it, Batman Beyond comes to mind as an example if I’m remembering correctly. Once again, it’s just going to be a matter of finding the start spot of the individual episode and inserting it manually. Or you can just fast forward through it.
There’s no real need to insert the chapters for the other commercial breaks, unless you wanted them. If I want to skip ahead through a show, I’ll skip by a minute or more, mapping a remote event with LIRC.
The only time the last issue bites me is when I’m manually checking a disc out. For some reason, a lot of them will have a chapter start time that is actually the end time of the episode. I don’t know why that is. What would be really nice is if the last chapter started at the end credits, because that way I could cut out even more stuff I’ll never watch, and again save on some disk space. That one would probably be easy to calculate as well, and no doubt it’s going to be a fixed amount of time (or really close) just like the intros. I haven’t had enough disk space issues yet to warrant investigating the problem just yet.
Bad chapters are just one symptom of poorly authored DVDs, for whatever reason. There’s a lot more things that can go wrong, and I’ll cover them when I get some time. All together, they are only small annoyances, but it does make things difficult when you want to automate the process as much as possible, and you can’t expect things to be right all the time. It’s stopping and coding around these inconsistencies that make creating a universal solution impossible.