This improves the PSNR of the trellis encodes (previously it was
worse than non-trellis for this codec) of IMA QT. This logic
has to be special cased for the IMA QT encoder though - for IMA WAV
it makes the PSNR slightly worse (but still better than non-trellis),
for ADPCM_YAMAHA it makes it much much worse.
---
Not sure if this is worthwhile, but right now the trellis option
for the IMA QT encoder basically only makes things (slightly)
worse (according to our own decoder).
---
libavcodec/adpcmenc.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)
diff --git a/libavcodec/adpcmenc.c b/libavcodec/adpcmenc.c
index 341dda4..ea457ad 100644
--- a/libavcodec/adpcmenc.c
+++ b/libavcodec/adpcmenc.c
@@ -390,7 +390,6 @@ static void adpcm_compress_trellis(AVCodecContext *avctx,
(ff_adpcm_AdaptationTable[nibble] * step) >>
8));
}
} else if (version == AV_CODEC_ID_ADPCM_IMA_WAV ||
- version == AV_CODEC_ID_ADPCM_IMA_QT ||
version == AV_CODEC_ID_ADPCM_SWF) {
#define LOOP_NODES(NAME, STEP_TABLE, STEP_INDEX)\
const int predictor = nodes[j]->sample1;\
@@ -410,11 +409,39 @@ static void adpcm_compress_trellis(AVCodecContext *avctx,
}
LOOP_NODES(ima, ff_adpcm_step_table[step],
av_clip(step + ff_adpcm_index_table[nibble], 0,
88));
- } else { //AV_CODEC_ID_ADPCM_YAMAHA
+ } else if (version == AV_CODEC_ID_ADPCM_YAMAHA) {
LOOP_NODES(yamaha, step,
av_clip((step * ff_adpcm_yamaha_indexscale[nibble])
>> 8,
127, 24567));
#undef LOOP_NODES
+ } else if (version == AV_CODEC_ID_ADPCM_IMA_QT) {
+#define LOOP_NODES(NAME, STEP_TABLE, STEP_INDEX) \
+ const int predictor = nodes[j]->sample1; \
+ const int div = (sample - predictor) * 4 / STEP_TABLE; \
+ int nmin = av_clip(div - range, -7, 6); \
+ int nmax = av_clip(div + range, -6, 7); \
+ if (nmin <= 0) \
+ nmin--; /* distinguish -0 from +0 */ \
+ if (nmax < 0) \
+ nmax--; \
+ for (nidx = nmin; nidx <= nmax; nidx++) { \
+ const int nibble = nidx < 0 ? 7 - nidx : nidx; \
+ int stepval = STEP_TABLE, mask, diff = stepval >> 3;\
+ int dec_sample; \
+ for (mask = 4; mask;) { \
+ if (nibble & mask) \
+ diff += stepval; \
+ stepval >>= 1; \
+ mask >>= 1; \
+ } \
+ if (nibble & 8) \
+ dec_sample = predictor - diff; \
+ else \
+ dec_sample = predictor + diff; \
+ STORE_NODE(NAME, STEP_INDEX); \
+ }
+ LOOP_NODES(ima_qt, ff_adpcm_step_table[step],
+ av_clip(step + ff_adpcm_index_table[nibble], 0,
88));
#undef STORE_NODE
}
}
--
1.8.5.2 (Apple Git-48)
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