[FFmpeg-devel] [PATCH 2/2] lavc/dxvenc: migrate DXT1 encoder to lavu hashtable
Connor Worley
connorbworley at gmail.com
Mon Feb 5 07:27:24 EET 2024
Offers a modest performance gain due to the switch from naive linear
probling to robin hood.
Signed-off-by: Connor Worley <connorbworley at gmail.com>
---
libavcodec/dxvenc.c | 121 +++++++++++++-------------------------------
1 file changed, 35 insertions(+), 86 deletions(-)
diff --git a/libavcodec/dxvenc.c b/libavcodec/dxvenc.c
index b274175689..e17b3b2c36 100644
--- a/libavcodec/dxvenc.c
+++ b/libavcodec/dxvenc.c
@@ -21,7 +21,7 @@
#include <stdint.h>
-#include "libavutil/crc.h"
+#include "libavutil/hashtable.h"
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
@@ -44,69 +44,6 @@ enum DXVTextureFormat {
DXV_FMT_DXT1 = MKBETAG('D', 'X', 'T', '1'),
};
-typedef struct HTEntry {
- uint32_t key;
- uint32_t pos;
-} HTEntry;
-
-static void ht_init(HTEntry *ht)
-{
- for (size_t i = 0; i < LOOKBACK_HT_ELEMS; i++) {
- ht[i].pos = -1;
- }
-}
-
-static uint32_t ht_lookup_and_upsert(HTEntry *ht, const AVCRC *hash_ctx,
- uint32_t key, uint32_t pos)
-{
- uint32_t ret = -1;
- size_t hash = av_crc(hash_ctx, 0, (uint8_t*)&key, 4) % LOOKBACK_HT_ELEMS;
- for (size_t i = hash; i < hash + LOOKBACK_HT_ELEMS; i++) {
- size_t wrapped_index = i % LOOKBACK_HT_ELEMS;
- HTEntry *entry = &ht[wrapped_index];
- if (entry->key == key || entry->pos == -1) {
- ret = entry->pos;
- entry->key = key;
- entry->pos = pos;
- break;
- }
- }
- return ret;
-}
-
-static void ht_delete(HTEntry *ht, const AVCRC *hash_ctx,
- uint32_t key, uint32_t pos)
-{
- HTEntry *removed_entry = NULL;
- size_t removed_hash;
- size_t hash = av_crc(hash_ctx, 0, (uint8_t*)&key, 4) % LOOKBACK_HT_ELEMS;
-
- for (size_t i = hash; i < hash + LOOKBACK_HT_ELEMS; i++) {
- size_t wrapped_index = i % LOOKBACK_HT_ELEMS;
- HTEntry *entry = &ht[wrapped_index];
- if (entry->pos == -1)
- return;
- if (removed_entry) {
- size_t candidate_hash = av_crc(hash_ctx, 0, (uint8_t*)&entry->key, 4) % LOOKBACK_HT_ELEMS;
- if ((wrapped_index > removed_hash && (candidate_hash <= removed_hash || candidate_hash > wrapped_index)) ||
- (wrapped_index < removed_hash && (candidate_hash <= removed_hash && candidate_hash > wrapped_index))) {
- *removed_entry = *entry;
- entry->pos = -1;
- removed_entry = entry;
- removed_hash = wrapped_index;
- }
- } else if (entry->key == key) {
- if (entry->pos <= pos) {
- entry->pos = -1;
- removed_entry = entry;
- removed_hash = wrapped_index;
- } else {
- return;
- }
- }
- }
-}
-
typedef struct DXVEncContext {
AVClass *class;
@@ -123,10 +60,8 @@ typedef struct DXVEncContext {
enum DXVTextureFormat tex_fmt;
int (*compress_tex)(AVCodecContext *avctx);
- const AVCRC *crc_ctx;
-
- HTEntry color_lookback_ht[LOOKBACK_HT_ELEMS];
- HTEntry lut_lookback_ht[LOOKBACK_HT_ELEMS];
+ AVHashtableContext color_ht;
+ AVHashtableContext lut_ht;
} DXVEncContext;
/* Converts an index offset value to a 2-bit opcode and pushes it to a stream.
@@ -161,27 +96,32 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
DXVEncContext *ctx = avctx->priv_data;
PutByteContext *pbc = &ctx->pbc;
uint32_t *value;
- uint32_t color, lut, idx, color_idx, lut_idx, prev_pos, state = 16, pos = 2, op = 0;
+ uint32_t color, lut, idx, color_idx, lut_idx, prev_pos, state = 16, pos = 0, op = 0;
- ht_init(ctx->color_lookback_ht);
- ht_init(ctx->lut_lookback_ht);
+ av_hashtable_clear(&ctx->color_ht);
+ av_hashtable_clear(&ctx->lut_ht);
bytestream2_put_le32(pbc, AV_RL32(ctx->tex_data));
+ av_hashtable_set(&ctx->color_ht, ctx->tex_data, &pos);
+ pos++;
bytestream2_put_le32(pbc, AV_RL32(ctx->tex_data + 4));
-
- ht_lookup_and_upsert(ctx->color_lookback_ht, ctx->crc_ctx, AV_RL32(ctx->tex_data), 0);
- ht_lookup_and_upsert(ctx->lut_lookback_ht, ctx->crc_ctx, AV_RL32(ctx->tex_data + 4), 1);
+ av_hashtable_set(&ctx->lut_ht, ctx->tex_data + 4, &pos);
+ pos++;
while (pos + 2 <= ctx->tex_size / 4) {
idx = 0;
+ color_idx = 0;
+ lut_idx = 0;
color = AV_RL32(ctx->tex_data + pos * 4);
- prev_pos = ht_lookup_and_upsert(ctx->color_lookback_ht, ctx->crc_ctx, color, pos);
- color_idx = prev_pos != -1 ? pos - prev_pos : 0;
+ if (av_hashtable_get(&ctx->color_ht, &color, &prev_pos))
+ color_idx = pos - prev_pos;
+ av_hashtable_set(&ctx->color_ht, &color, &pos);
+
if (pos >= LOOKBACK_WORDS) {
uint32_t old_pos = pos - LOOKBACK_WORDS;
- uint32_t old_color = AV_RL32(ctx->tex_data + old_pos * 4);
- ht_delete(ctx->color_lookback_ht, ctx->crc_ctx, old_color, old_pos);
+ if (av_hashtable_get(&ctx->color_ht, ctx->tex_data + old_pos * 4, &prev_pos) && prev_pos <= old_pos)
+ av_hashtable_delete(&ctx->color_ht, ctx->tex_data + old_pos * 4);
}
pos++;
@@ -190,13 +130,14 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
idx = color_idx;
} else {
idx = 0;
- prev_pos = ht_lookup_and_upsert(ctx->lut_lookback_ht, ctx->crc_ctx, lut, pos);
- lut_idx = prev_pos != -1 ? pos - prev_pos : 0;
+ if (av_hashtable_get(&ctx->lut_ht, &lut, &prev_pos))
+ lut_idx = pos - prev_pos;
+ av_hashtable_set(&ctx->lut_ht, &lut, &pos);
}
if (pos >= LOOKBACK_WORDS) {
uint32_t old_pos = pos - LOOKBACK_WORDS;
- uint32_t old_lut = AV_RL32(ctx->tex_data + old_pos * 4);
- ht_delete(ctx->lut_lookback_ht, ctx->crc_ctx, old_lut, old_pos);
+ if (av_hashtable_get(&ctx->lut_ht, ctx->tex_data + old_pos * 4, &prev_pos) && prev_pos <= old_pos)
+ av_hashtable_delete(&ctx->lut_ht, ctx->tex_data + old_pos * 4);
}
pos++;
@@ -298,10 +239,15 @@ static av_cold int dxv_init(AVCodecContext *avctx)
return AVERROR(ENOMEM);
}
- ctx->crc_ctx = av_crc_get_table(AV_CRC_32_IEEE);
- if (!ctx->crc_ctx) {
- av_log(avctx, AV_LOG_ERROR, "Could not initialize CRC table.\n");
- return AVERROR_BUG;
+ ret = av_hashtable_init(&ctx->color_ht, sizeof(uint32_t), sizeof(uint32_t), LOOKBACK_HT_ELEMS);
+ if (ret < 0) {
+ av_log(avctx, AV_LOG_ERROR, "Could not initialize color lookback table.\n");
+ return ret;
+ }
+ ret = av_hashtable_init(&ctx->lut_ht, sizeof(uint32_t), sizeof(uint32_t), LOOKBACK_HT_ELEMS);
+ if (ret < 0) {
+ av_log(avctx, AV_LOG_ERROR, "Could not initialize LUT lookback table.\n");
+ return ret;
}
return 0;
@@ -313,6 +259,9 @@ static av_cold int dxv_close(AVCodecContext *avctx)
av_freep(&ctx->tex_data);
+ av_hashtable_destroy(&ctx->color_ht);
+ av_hashtable_destroy(&ctx->lut_ht);
+
return 0;
}
--
2.40.1
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