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Old 2004-12-07, 12:25 PM
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Join Date: Oct 2004
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Re: Expansion of SHN > FLAC question

Quote:
Originally Posted by katnapz
Regardless of whether you take the original SHNs and convert them to FLAC (or vice versa), as long as you keep the original fingerprint or md5 for verification purposes of the original format they are the same. If you run into someone who screams about the show originally being in SHN format because they have the md5 from some online archive you can always convert your FLAC back to SHN for purposes of trading.
This is only partially true...I know we talked about this issue before. SHN files have several problems that will make it difficult to match the wholefile md5 back. There are quite a few things that can wrong here, which is why I am insisting so stronly on shntool md5, as it only looks at the audio content. With this, you can do any number of transtions, in any direction, and it will ALWAYS verify. However, for the purposes you're stating, that is, helping with reseeds, it will look at wholefile md5 sums, which will not verify if at least one of the following things has happened.

1. There can be extra header data appending to a WAV file and subsequently an SHN. FLAC strips this data, which does not affect the audio. But it will change the wholefile md5. So going SHN > FLAC > SHN will cause the end SHN files to be a different md5 than the originals. Some may falsely assume that your computer screwed up, but if you have the shntool md5s from each of the steps, you can confirm that this is not the case. Note that there is no way to get that striped header data BACK, so if this happens, you will never again be able to verify to the original md5. To check if there is additional data BEFORE making the conversion, run an shntool len check and see if you get any "e" or "h" errors.

2. There are several different options for seektables. Not only are there two different versions of seektables, but many files are created without them. Changing this will alter the wholefile md5 as well. So if you go from SHN > FLAC > SHN you have to make sure that you check if and what type of seektables are there on the original file, and append that type to the SHNs when you remake them.

If anything, people should just get in the habit of using shntool md5s and then this whole fight becomes completely moot.
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