@@ -62,14 +62,17 @@ typedef struct SmackVContext {
int mmap_last[3], mclr_last[3], full_last[3], type_last[3];
} SmackVContext;
+typedef struct HuffEntry {
+ uint8_t value;
+ uint8_t length;
+} HuffEntry;
+
/**
* Context used for code reconstructing
*/
typedef struct HuffContext {
int current;
- uint32_t bits[256];
- uint8_t lengths[256];
- uint8_t values[256];
+ HuffEntry entries[256];
} HuffContext;
/* common parameters used for decode_bigtree */
@@ -105,7 +108,7 @@ enum SmkBlockTypes {
* Can read SMKTREE_DECODE_MAX_RECURSION before the first check;
* does not overread gb on success.
*/
-static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t prefix, int length)
+static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, int length)
{
if (length > SMKTREE_DECODE_MAX_RECURSION || length > 3 * SMKTREE_BITS) {
av_log(NULL, AV_LOG_ERROR, "Maximum tree recursion level exceeded.\n");
@@ -119,18 +122,15 @@ static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t pref
}
if (get_bits_left(gb) < 8)
return AVERROR_INVALIDDATA;
- hc->bits[hc->current] = prefix;
- hc->lengths[hc->current] = length;
- hc->values[hc->current] = get_bits(gb, 8);
- hc->current++;
+ hc->entries[hc->current++] = (HuffEntry){ get_bits(gb, 8), length };
return 0;
} else { //Node
int r;
length++;
- r = smacker_decode_tree(gb, hc, prefix, length);
+ r = smacker_decode_tree(gb, hc, length);
if(r)
return r;
- return smacker_decode_tree(gb, hc, prefix | (1U << (length - 1)), length);
+ return smacker_decode_tree(gb, hc, length);
}
}
@@ -216,22 +216,21 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
i ? "high" : "low");
continue;
}
- err = smacker_decode_tree(gb, &h, 0, 0);
+ err = smacker_decode_tree(gb, &h, 0);
if (err < 0)
goto error;
skip_bits1(gb);
if (h.current > 1) {
- err = ff_init_vlc_sparse(&vlc[i], SMKTREE_BITS, h.current,
- h.lengths, sizeof(*h.lengths), sizeof(*h.lengths),
- h.bits, sizeof(*h.bits), sizeof(*h.bits),
- h.values, sizeof(*h.values), sizeof(*h.values),
- INIT_VLC_LE);
+ err = ff_init_vlc_from_lengths(&vlc[i], SMKTREE_BITS, h.current,
+ &h.entries[0].length, sizeof(*h.entries),
+ &h.entries[0].value, sizeof(*h.entries), 1,
+ 0, INIT_VLC_OUTPUT_LE, smk->avctx);
if (err < 0) {
av_log(smk->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
goto error;
}
} else
- ctx.vals[i] = h.values[0];
+ ctx.vals[i] = h.entries[0].value;
}
escapes[0] = get_bits(gb, 16);
@@ -650,21 +649,20 @@ static int smka_decode_frame(AVCodecContext *avctx, void *data,
HuffContext h;
h.current = 0;
skip_bits1(&gb);
- if ((ret = smacker_decode_tree(&gb, &h, 0, 0)) < 0)
+ if ((ret = smacker_decode_tree(&gb, &h, 0)) < 0)
goto error;
skip_bits1(&gb);
if (h.current > 1) {
- ret = ff_init_vlc_sparse(&vlc[i], SMKTREE_BITS, h.current,
- h.lengths, sizeof(*h.lengths), sizeof(*h.lengths),
- h.bits, sizeof(*h.bits), sizeof(*h.bits),
- h.values, sizeof(*h.values), sizeof(*h.values),
- INIT_VLC_LE);
+ ret = ff_init_vlc_from_lengths(&vlc[i], SMKTREE_BITS, h.current,
+ &h.entries[0].length, sizeof(*h.entries),
+ &h.entries[0].value, sizeof(*h.entries), 1,
+ 0, INIT_VLC_OUTPUT_LE, avctx);
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
goto error;
}
} else
- values[i] = h.values[0];
+ values[i] = h.entries[0].value;
}
/* this codec relies on wraparound instead of clipping audio */
if(bits) { //decode 16-bit data
The Smacker Huffman tables are already stored in a tree-like structure; in particular, they are naturally ordered from left to right in the tree and are therefore suitable to be initialized by ff_init_vlc_from_lengths() which avoids traversing the data twice in order to sort only the codes that are so long that they need into a subtable. This improves performance (and reduces codesize): For the sample from ticket #2425 the number of decicycles for parsing and creating the VLCs in smka_decode_frame() decreased from 412322 to 359152 (tested with 10 runs each looping 20 times over the file). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> --- libavcodec/smacker.c | 46 +++++++++++++++++++++----------------------- 1 file changed, 22 insertions(+), 24 deletions(-)