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libavfilter/vf_slicify.c

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00001 /*
00002  * copyright (c) 2007 Bobby Bingham
00003  *
00004  * This file is part of FFmpeg.
00005  *
00006  * FFmpeg is free software; you can redistribute it and/or
00007  * modify it under the terms of the GNU Lesser General Public
00008  * License as published by the Free Software Foundation; either
00009  * version 2.1 of the License, or (at your option) any later version.
00010  *
00011  * FFmpeg is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with FFmpeg; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00019  */
00020 
00026 #include "avfilter.h"
00027 #include "libavutil/pixdesc.h"
00028 
00029 typedef struct {
00030     int h;          
00031     int vshift;     
00032     uint32_t lcg_state; 
00033     int use_random_h;   
00034 } SliceContext;
00035 
00036 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
00037 {
00038     SliceContext *slice = ctx->priv;
00039 
00040     slice->h = 16;
00041     if (args) {
00042         if (!strcmp(args, "random")) {
00043             slice->use_random_h = 1;
00044         } else {
00045             sscanf(args, "%d", &slice->h);
00046         }
00047     }
00048     return 0;
00049 }
00050 
00051 static int config_props(AVFilterLink *link)
00052 {
00053     SliceContext *slice = link->dst->priv;
00054 
00055     slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
00056 
00057     return 0;
00058 }
00059 
00060 static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
00061 {
00062     SliceContext *slice = link->dst->priv;
00063 
00064     if (slice->use_random_h) {
00065         slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
00066         slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
00067     }
00068 
00069     /* ensure that slices play nice with chroma subsampling, and enforce
00070      * a reasonable minimum size for the slices */
00071     slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
00072 
00073     av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
00074 
00075     avfilter_start_frame(link->dst->outputs[0], picref);
00076 }
00077 
00078 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
00079 {
00080     SliceContext *slice = link->dst->priv;
00081     int y2;
00082 
00083     if (slice_dir == 1) {
00084         for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
00085             avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
00086 
00087         if (y2 < y + h)
00088             avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
00089     } else if (slice_dir == -1) {
00090         for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h)
00091             avfilter_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
00092 
00093         if (y2 > y)
00094             avfilter_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
00095     }
00096 }
00097 
00098 AVFilter avfilter_vf_slicify = {
00099     .name      = "slicify",
00100     .description = "Pass the images of input video on to next video filter as multiple slices.",
00101 
00102     .init      = init,
00103 
00104     .priv_size = sizeof(SliceContext),
00105 
00106     .inputs    = (AVFilterPad[]) {{ .name             = "default",
00107                                     .type             = AVMEDIA_TYPE_VIDEO,
00108                                     .get_video_buffer = avfilter_null_get_video_buffer,
00109                                     .start_frame      = start_frame,
00110                                     .draw_slice       = draw_slice,
00111                                     .config_props     = config_props,
00112                                     .end_frame        = avfilter_null_end_frame, },
00113                                   { .name = NULL}},
00114     .outputs   = (AVFilterPad[]) {{ .name            = "default",
00115                                     .type            = AVMEDIA_TYPE_VIDEO, },
00116                                   { .name = NULL}},
00117 };

Generated on Fri Sep 16 2011 17:17:47 for FFmpeg by  doxygen 1.7.1