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Songbird Issue / Question - ID3v2?
Sunraycer
post Jul 18 2011, 06:01
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When loading a a WavPack file into Songbird it shows the incorrect track time. It shows the other tags, artist, etc, correctly. After playing the track for a few seconds, the track time updates to the correct time. And stays correct from then on.

Does anyone have an idea of why this is? I was thinking that maybe it's due to the Ape or ID3v1 tags. Reading some other posts on this board I'm wondering if it has to do with WavPack files having the metadata at the end of the file?


Does anyone know why WavPack supports only ID3v1 and not ID3v2? Just curious...
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bryant
post Jul 19 2011, 18:03
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It’s actually a little odd that Songbird is not showing the length correctly, and even weirder that it corrects the value after playing starts. I think I have an idea though.

As was said, the total duration of an audio file is a fundamental piece of info and is stored unambiguously in the WavPack header, so it should be available on opening the WavPack file (presumably with the WavPack library). However, it might be that Songbird does not really open the file until it’s actually going to play it, and has some other metadata parser that tries to get basic info (including length) that operates when just browsing (this is, for example, how Rockbox works). Now, if there is a bug in that metadata parser it might get the length wrong at that time, but then once play starts it uses the length that the library returns.

This problem could also be triggered if your WavPack files were created by one of the few programs that [incorrectly] neglect making the finalizing call to the WavPack library that puts the final length in the header (cuesplitter is one). In that case it’s impossible to know the length without seeking out to the end and examining the last audio block, or guessing the length by using the encoding mode and the file length (again, something that I implemented in Rockbox to handle this). A way to test for this would be to grab a file from the WavPack test suite (which are known to be correct) and see how that plays.

The story with WavPack and tags is that WavPack is old enough (it predates FLAC and Monkey’s Audio) that ID3v1 tags were initially the best choice. When Monkey’s Audio APE tags became available I decided to support them also and so there was never a need to deal with ID3v2.
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