adl: Add crude loop detection#126
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The adl driver doesn't detect looping songs and plays them forever. In theory, the file format allows for quite complex channel control flow, and a reliable detection whether a song is endlessly repeating previously played parts is not feasible. In practice, for the music actually released in this format, a simple check seems to be good enough (although it's easy to craft malicious examples where this check fails; both false positives and false negatives): Let's assume a song is repeating if all channels which are still playing have jumped back or are (transitively) waiting on channels which have jumped back. Bug: adplug#122
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Might another approach be to do the same as for IMF. Make a database for limiting the length per subsong, and we could also add hiding of non-used subsongs. |
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How is this one going, do you think it's ready to merge? |
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Haven't been working on adplug for a while (real life…) I think the PR is ready to merge if you like the approach. Didn't merge myself because I'm not sure whether it's the right thing to do to deal with the issue. It's not a perfect solution, but well, it's an improvement; nobody complained or proposed a better solution, so I'd say go ahead. |
binarymaster
approved these changes
Dec 1, 2022
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Trying to avoid endlessly playing .adl files. Detecting loops properly would be way too complex, so I'm using a simple heuristics instead. Some testing wouldn't hurt.
In my tests with the music from Dune II, Legend of Kyrandia, and the playertest files all endless loops were eliminated, but I haven't checked whether some parts are missing now. If someone wants to check, the previously endless songs (and their new length) are:
(The Kyra files contain very long subsongs up to 75 min. They repeat a finite number of times and I deliberately left them as is.)