[vorbis] OGG Edge artifacts due to compression

[Michael Smith]

On Tuesday 25 February 2003 05:15, Scott Velasquez wrote:
> Hello all,
>
> I'm finishing up a sound engine for a PC game product which uses Vorbis
> to playback OGG music samples.  However, I've run into a problem with
> edge artifacts on sounds that need to either loop back onto themselves
> or into other music tracks, without fading.  I've also experienced this
> same problem on large music files that are broken up into smaller
> permutations to save sound cache space.  The ending sample of one
> permutation will not always match the beginning sample of another
> permutation.  I got around this problem with XBOX ADPCM by using
> seamless lead-in and lead-out bytes, but because of the nature of OGG, I
> don't think it's that simple.
>
> Just as a test, I tried compressing 1K of extra data (which was a see
> saw effect starting with the last sample value) which was attached it to
> the end of each permutation, and then decompress it with the original
> size.  This didn't work I'm sure because I need to physically edit the
> Vorbisfile to remove the extra data before decompression.

I wrote a tool called "vcut" to do this - it's not perfect, but it may work 
fine for your purposes. It'll cut off the vorbis file at a sample-exact 
location, so you can encode as much extra data as you find appropriate (at 
the start and end, possibly), and then later cut those off. (vcut is 
distributed as part of vorbis-tools)

Mike

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