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adpcm: Use a hash table to improve checking for duplicate samples
This lowers the run time from 158 to 21 seconds, for -trellis 8 with a 30 second sample on my machine. This requires 64 KB additional memory. Originally committed as revision 25768 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -163,6 +163,7 @@ typedef struct ADPCMContext {
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TrellisPath *paths;
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TrellisNode *node_buf;
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TrellisNode **nodep_buf;
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uint8_t *trellis_hash;
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} ADPCMContext;
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#define FREEZE_INTERVAL 128
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@ -189,6 +190,7 @@ static av_cold int adpcm_encode_init(AVCodecContext *avctx)
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FF_ALLOC_OR_GOTO(avctx, s->paths, max_paths * sizeof(*s->paths), error);
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FF_ALLOC_OR_GOTO(avctx, s->node_buf, 2 * frontier * sizeof(*s->node_buf), error);
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FF_ALLOC_OR_GOTO(avctx, s->nodep_buf, 2 * frontier * sizeof(*s->nodep_buf), error);
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FF_ALLOC_OR_GOTO(avctx, s->trellis_hash, 65536 * sizeof(*s->trellis_hash), error);
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}
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switch(avctx->codec->id) {
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@ -242,6 +244,7 @@ error:
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av_freep(&s->paths);
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av_freep(&s->node_buf);
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av_freep(&s->nodep_buf);
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av_freep(&s->trellis_hash);
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return -1;
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}
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@ -252,6 +255,7 @@ static av_cold int adpcm_encode_close(AVCodecContext *avctx)
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av_freep(&s->paths);
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av_freep(&s->node_buf);
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av_freep(&s->nodep_buf);
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av_freep(&s->trellis_hash);
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return 0;
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}
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@ -325,7 +329,9 @@ static void adpcm_compress_trellis(AVCodecContext *avctx, const short *samples,
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TrellisNode **nodep_buf = s->nodep_buf;
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TrellisNode **nodes = nodep_buf; // nodes[] is always sorted by .ssd
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TrellisNode **nodes_next = nodep_buf + frontier;
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int pathn = 0, froze = -1, i, j, k;
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int pathn = 0, froze = -1, i, j, k, generation = 0;
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uint8_t *hash = s->trellis_hash;
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memset(hash, 0xff, 65536 * sizeof(*hash));
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memset(nodep_buf, 0, 2 * frontier * sizeof(*nodep_buf));
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nodes[0] = node_buf + frontier;
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@ -372,18 +378,24 @@ static void adpcm_compress_trellis(AVCodecContext *avctx, const short *samples,
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uint32_t ssd;\
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int pos;\
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TrellisNode *u;\
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uint8_t *h;\
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dec_sample = av_clip_int16(dec_sample);\
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d = sample - dec_sample;\
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ssd = nodes[j]->ssd + d*d;\
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/* Collapse any two states with the same previous sample value. \
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* One could also distinguish states by step and by 2nd to last
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* sample, but the effects of that are negligible. */\
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for(k=0; k<frontier && nodes_next[k]; k++) {\
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if(dec_sample == nodes_next[k]->sample1) {\
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assert(ssd >= nodes_next[k]->ssd);\
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goto next_##NAME;\
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}\
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}\
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* sample, but the effects of that are negligible.
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* Since nodes in the previous generation are iterated
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* through a heap, they're roughly ordered from better to
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* worse, but not strictly ordered. Therefore, an earlier
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* node with the same sample value is better in most cases
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* (and thus the current is skipped), but not strictly
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* in all cases. Only skipping samples where ssd >=
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* ssd of the earlier node with the same sample gives
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* slightly worse quality, though, for some reason. */ \
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h = &hash[(uint16_t) dec_sample];\
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if (*h == generation)\
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goto next_##NAME;\
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if (heap_pos < frontier) {\
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pos = heap_pos++;\
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} else {\
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@ -393,6 +405,7 @@ static void adpcm_compress_trellis(AVCodecContext *avctx, const short *samples,
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if (ssd > nodes_next[pos]->ssd)\
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goto next_##NAME;\
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}\
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*h = generation;\
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u = nodes_next[pos];\
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if(!u) {\
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assert(pathn < FREEZE_INTERVAL<<avctx->trellis);\
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@ -443,6 +456,12 @@ static void adpcm_compress_trellis(AVCodecContext *avctx, const short *samples,
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nodes = nodes_next;
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nodes_next = u;
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generation++;
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if (generation == 255) {
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memset(hash, 0xff, 65536 * sizeof(*hash));
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generation = 0;
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}
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// prevent overflow
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if(nodes[0]->ssd > (1<<28)) {
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for(j=1; j<frontier && nodes[j]; j++)
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