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| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-03-03 14:45:14 +0100 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-03-03 14:45:14 +0100 |
| commit | f7ab9fb52a0d50db3e5de67e74f1654ad374ae59 (patch) | |
| tree | 42bcf6ed34290dc490d64a7e2414bef1f76cf9fe | |
| parent | 7fc78023587e6cb238d5fa16f5acafb4078c6798 (diff) | |
| download | plan9front-f7ab9fb52a0d50db3e5de67e74f1654ad374ae59.tar.xz | |
pcmconv: revert previous change, fix dither clipping
previous change had forgot how dithering works... m(
we *really* add a random signal when *reducing* the number
of bits. just make sure we do not overflow like in
mixin().
| -rw-r--r-- | sys/src/cmd/audio/pcmconv/pcmconv.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/sys/src/cmd/audio/pcmconv/pcmconv.c b/sys/src/cmd/audio/pcmconv/pcmconv.c index 0c9cba35c..3adda141a 100644 --- a/sys/src/cmd/audio/pcmconv/pcmconv.c +++ b/sys/src/cmd/audio/pcmconv/pcmconv.c @@ -209,12 +209,13 @@ dither(int *y, int ibits, int obits, int count) { static ulong prnd; - if(ibits >= 32 || ibits >= obits) + if(ibits >= 32 || obits >= ibits) return; while(count--){ prnd = (prnd*0x19660dL + 0x3c6ef35fL) & 0xffffffffL; - *y++ += ((int)prnd) >> ibits; + *y = clip((vlong)*y + ((int)prnd >> ibits)); + y++; } } |