From ec7ab610d51508344273dbc38fec4ab6034bf1e2 Mon Sep 17 00:00:00 2001 From: Stefano Sabatini Date: Sat, 13 Mar 2010 10:41:25 +0000 Subject: [PATCH] Extend the slice filter to make it issue slice height values randomly choosen between 8 and 32 when the supplied parameter is the string "random". This is useful for testing the slice support, but it is not supposed to be used for other purposes and this interface may change in the future, thus it is not documented. The randomization algorithm adopted is the standard Numerical Recipes LCG. Originally committed as revision 22505 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavfilter/vf_slicify.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/libavfilter/vf_slicify.c b/libavfilter/vf_slicify.c index d1c9fbc6ac..e2ac594611 100644 --- a/libavfilter/vf_slicify.c +++ b/libavfilter/vf_slicify.c @@ -29,6 +29,8 @@ typedef struct { int h; ///< output slice height int vshift; ///< vertical chroma subsampling shift + uint32_t lcg_state; ///< LCG state used to compute random slice height + int use_random_h; ///< enable the use of random slice height values } SliceContext; static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque) @@ -36,9 +38,13 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque) SliceContext *slice = ctx->priv; slice->h = 16; - if (args) - sscanf(args, "%d", &slice->h); - + if (args) { + if (!strcmp(args, "random")) { + slice->use_random_h = 1; + } else { + sscanf(args, "%d", &slice->h); + } + } return 0; } @@ -48,12 +54,6 @@ static int config_props(AVFilterLink *link) slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h; - /* ensure that slices play nice with chroma subsampling, and enforce - * a reasonable minimum size for the slices */ - slice->h = FFMAX(8, slice->h & (-1 << slice->vshift)); - - av_log(link->dst, AV_LOG_INFO, "h:%d\n", slice->h); - return 0; } @@ -65,6 +65,19 @@ static AVFilterPicRef *get_video_buffer(AVFilterLink *link, int perms, static void start_frame(AVFilterLink *link, AVFilterPicRef *picref) { + SliceContext *slice = link->dst->priv; + + if (slice->use_random_h) { + slice->lcg_state = slice->lcg_state * 1664525 + 1013904223; + slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX; + } + + /* ensure that slices play nice with chroma subsampling, and enforce + * a reasonable minimum size for the slices */ + slice->h = FFMAX(8, slice->h & (-1 << slice->vshift)); + + av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h); + avfilter_start_frame(link->dst->outputs[0], picref); }