Improves speed 102->2 sec Testcase: 8655/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DVBSUB_fuzzer-6277869285146624 Fixes: Timeout
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> --- libavcodec/dvbsubdec.c | 44 ++++++++++++++++++++++++------------------ 1 file changed, 25 insertions(+), 19 deletions(-) diff --git a/libavcodec/dvbsubdec.c b/libavcodec/dvbsubdec.c index a657b1d3d0..b59e836657 100644 --- a/libavcodec/dvbsubdec.c +++ b/libavcodec/dvbsubdec.c @@ -127,6 +127,7 @@ typedef struct DVBSubContext { int compute_edt; /**< if 1 end display time calculated using pts if 0 (Default) calculated using time out */ int compute_clut; + int clut_count2[257][256]; int substream; int64_t prev_start; DVBSubRegion *region_list; @@ -650,13 +651,17 @@ static int dvbsub_read_8bit_string(AVCodecContext *avctx, return pixels_read; } -static void compute_default_clut(uint8_t *clut, AVSubtitleRect *rect, int w, int h) +static void compute_default_clut(DVBSubContext *ctx, uint8_t *clut, AVSubtitleRect *rect, int w, int h) { uint8_t list[256] = {0}; uint8_t list_inv[256]; int counttab[256] = {0}; + int (*counttab2)[256] = ctx->clut_count2; int count, i, x, y; ptrdiff_t stride = rect->linesize[0]; + + memset(ctx->clut_count2, 0 , sizeof(ctx->clut_count2)); + #define V(x,y) rect->data[0][(x) + (y)*stride] for (y = 0; y<h; y++) { for (x = 0; x<w; x++) { @@ -666,31 +671,32 @@ static void compute_default_clut(uint8_t *clut, AVSubtitleRect *rect, int w, int int vt = y ? V(x,y-1) + 1 : 0; int vb = y+1<h ? V(x,y+1) + 1 : 0; counttab[v-1] += !!((v!=vl) + (v!=vr) + (v!=vt) + (v!=vb)); + counttab2[vl][v-1] ++; + counttab2[vr][v-1] ++; + counttab2[vt][v-1] ++; + counttab2[vb][v-1] ++; } } #define L(x,y) list[d[(x) + (y)*stride]] for (i = 0; i<256; i++) { - int scoretab[256] = {0}; + counttab2[i+1][i] = 0; + } + for (i = 0; i<256; i++) { int bestscore = 0; int bestv = 0; - for (y = 0; y<h; y++) { - for (x = 0; x<w; x++) { - uint8_t *d = &rect->data[0][x + y*stride]; - int v = *d; - int l_m = list[v]; - int l_l = x ? L(-1, 0) : 1; - int l_r = x+1<w ? L( 1, 0) : 1; - int l_t = y ? L( 0,-1) : 1; - int l_b = y+1<h ? L( 0, 1) : 1; - if (l_m) - continue; - scoretab[v] += l_l + l_r + l_t + l_b; - } - } + for (x = 0; x < 256; x++) { - if (scoretab[x]) { - int score = 1024LL*scoretab[x] / counttab[x]; + int scorev = 0; + if (list[x]) + continue; + scorev += counttab2[0][x]; + for (y = 0; y < 256; y++) { + scorev += list[y] * counttab2[y+1][x]; + } + + if (scorev) { + int score = 1024LL*scorev / counttab[x]; if (score > bestscore) { bestscore = score; bestv = x; @@ -819,7 +825,7 @@ static int save_subtitle_set(AVCodecContext *avctx, AVSubtitle *sub, int *got_ou if ((clut == &default_clut && ctx->compute_clut == -1) || ctx->compute_clut == 1) { if (!region->has_computed_clut) { - compute_default_clut(region->computed_clut, rect, rect->w, rect->h); + compute_default_clut(ctx, region->computed_clut, rect, rect->w, rect->h); region->has_computed_clut = 1; } -- 2.17.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
