`ParseNextPage()` in oggreader.go does not handle OPUS packets that span multiple segments

[martinflorek]

Your environment.

• Version: master

What did you do?

Decoding SILK OGG OPUS streams and some of them are changing from to CELT codec after some time and thus failing.

What did you expect?

Proper decoding of the of the whole SILK encoded stream

What happened?

oggreader returned error that CELT is not supported

Fix

The problem is in the loop that is reading the segments. It does not handle the case if the segment's length is 255, which means that the OPUS packet spans multiple segments

opus/pkg/oggreader/oggreader.go

Line 157 in 8667a1a

for _, s := range sizeBuffer {

Pseudo code of the correct loop can be found at https://gist.github.com/amishshah/68548e803c3208566e36e55fe1618e1c

Implementing something similar in my own, heavily modified oggreader, solved all the decoding problems.