From b304244b54611e9a84e22ab40e94be4a7a474c21 Mon Sep 17 00:00:00 2001 From: Baptiste Coudurier Date: Wed, 7 Sep 2011 22:27:03 -0400 Subject: adpcmenc: fix QT IMA ADPCM encoder Signed-off-by: Michael Niedermayer --- libavcodec/adpcmenc.c | 39 +++++++++++++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 4 deletions(-) (limited to 'libavcodec/adpcmenc.c') diff --git a/libavcodec/adpcmenc.c b/libavcodec/adpcmenc.c index ec062849bd..6295eedc55 100644 --- a/libavcodec/adpcmenc.c +++ b/libavcodec/adpcmenc.c @@ -164,6 +164,39 @@ static inline unsigned char adpcm_ima_compress_sample(ADPCMChannelStatus *c, sho return nibble; } +static inline unsigned char adpcm_ima_qt_compress_sample(ADPCMChannelStatus *c, short sample) +{ + int delta = sample - c->prev_sample; + int mask, step = ff_adpcm_step_table[c->step_index]; + int diff = step >> 3; + int nibble = 0; + + if (delta < 0) { + nibble = 8; + delta = -delta; + } + + for (mask = 4; mask;) { + if (delta >= step) { + nibble |= mask; + delta -= step; + diff += step; + } + step >>= 1; + mask >>= 1; + } + + if (nibble & 8) + c->prev_sample -= diff; + else + c->prev_sample += diff; + + c->prev_sample = av_clip_int16(c->prev_sample); + c->step_index = av_clip(c->step_index + ff_adpcm_index_table[nibble], 0, 88); + + return nibble; +} + static inline unsigned char adpcm_ms_compress_sample(ADPCMChannelStatus *c, short sample) { int predictor, nibble, bias; @@ -497,16 +530,14 @@ static int adpcm_encode_frame(AVCodecContext *avctx, adpcm_compress_trellis(avctx, samples+ch, buf, &c->status[ch], 64); for(i=0; i<64; i++) put_bits(&pb, 4, buf[i^1]); - c->status[ch].prev_sample = c->status[ch].predictor & ~0x7F; } else { for (i=0; i<64; i+=2){ int t1, t2; - t1 = adpcm_ima_compress_sample(&c->status[ch], samples[avctx->channels*(i+0)+ch]); - t2 = adpcm_ima_compress_sample(&c->status[ch], samples[avctx->channels*(i+1)+ch]); + t1 = adpcm_ima_qt_compress_sample(&c->status[ch], samples[avctx->channels*(i+0)+ch]); + t2 = adpcm_ima_qt_compress_sample(&c->status[ch], samples[avctx->channels*(i+1)+ch]); put_bits(&pb, 4, t2); put_bits(&pb, 4, t1); } - c->status[ch].prev_sample &= ~0x7F; } } -- cgit v1.2.3