On Fri, Jun 17, 2016 at 12:26 PM, Jean-Marc Valin <[email protected]> wrote: > My proposed solution is to fix the folding behaviour so that it is > never forced to fall back to LCG due to not enough folding data. This > is achieved by simply repeating part of the first band in the folding > of the second band. The proposed patch is available at: > https://git.xiph.org/?p=opus.git;a=commitdiff;h=949c7f33181 > It's a decoder-only change and it fixes the low-bitrate pre-echo > problem. I uploaded a short example that demonstrates the problem and > the fix. This is before the change: > http://jmvalin.ca/misc_stuff/fix_before.wav > and this is after the change: > http://jmvalin.ca/misc_stuff/fix_after.wav > Note especially the "t" in the word "tour", which has noticeable HF > pre-echo in the "before" file. Both files are decoded from the same 16 > kb/s CBR bit-stream. > > The fix does not impact compatibility, because the improvement does > not depend on the encoder doing anything special. I also do not see > any case where an encoder could have effectively used the current > broken behaviour to improve quality over the proposed change. > > For these reasons, I think it should be included in the update draft.
This appears reasonable to me, and I also do not see a way in which the old behavior could be usefully used, or any way that this would be likely to cause serious incompatibility. _______________________________________________ codec mailing list [email protected] https://www.ietf.org/mailman/listinfo/codec
