On Fri, May 29, 2020 at 03:47:03AM +0000, Zane van Iperen wrote: > On Thu, 28 May 2020 18:44:55 +0200 > "Michael Niedermayer" <mich...@niedermayer.cc> wrote: > > > > > The index table should only ever be indexed between [0,7], so this > > > looks like a bug in adpcm_ima_cunning_expand_nibble() instead. > > > > maybe it should be only 0..7 but abs(-8 .. 7) needs a 8th entrty or a > > check > > > > > > > > > > Where would one go to see the inputs for this? I'd like to > > > investigate (and test against the original decoder). > > > > The file is from a fuzzer so is random trash and it needs > > target_dec_fuzzer.c to be read. It wont be read as "Pro Pinball > > Series Soundbank" so i think that file will not be useful to test the > > behavior of the original decoder as i would assume it will not accept > > the target_dec_fuzzer data but i surely can send it to you privatly > > if you need it. just say if you want me to send you the file > > > > No need, I've found an existing file that has the same problem. Out of > all the 453 files I have, only one of them triggers this. > > tl;dr: Change the 5 to -1. > > > ff_adpcm_ima_cunning_index_table[abs(nibble)] is wrong in the case > where nibble == -8. > > If you take the unsigned nibble, and apply f(): > f(x) = 16 - x if x > 8 else x & 0x7 > > you'll get the same value as abs() applied with the signed nibble, > except for this one case (abs(-8) == 8, f(8) == 0). > > > Instead of changing the abs(), a cleaner fix is to simply change the 5 > to -1. That should give the correct output.
will apply with -1 thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I have never wished to cater to the crowd; for what I know they do not approve, and what they approve I do not know. -- Epicurus
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