Fix possible segfault
[ffmpeg.git] / libavfilter / avfiltergraph.c
1 /*
2  * Filter graphs
3  * copyright (c) 2007 Bobby Bingham
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21
22 #include <string.h>
23 #include <stddef.h>
24
25 #include "avfilter.h"
26 #include "avfiltergraph.h"
27
28 struct AVFilterGraph {
29     unsigned filter_count;
30     AVFilterContext **filters;
31 };
32
33 AVFilterGraph *avfilter_create_graph(void)
34 {
35     return av_mallocz(sizeof(AVFilterGraph));
36 }
37
38 static void destroy_graph_filters(AVFilterGraph *graph)
39 {
40     unsigned i;
41
42     for(i = 0; i < graph->filter_count; i ++)
43         avfilter_destroy(graph->filters[i]);
44     av_freep(&graph->filters);
45 }
46
47 void avfilter_destroy_graph(AVFilterGraph *graph)
48 {
49     destroy_graph_filters(graph);
50     av_free(graph);
51 }
52
53 void avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
54 {
55     graph->filters = av_realloc(graph->filters,
56                                 sizeof(AVFilterContext*) * ++graph->filter_count);
57     graph->filters[graph->filter_count - 1] = filter;
58 }
59
60 static AVFilterContext *create_filter_with_args(char *filter)
61 {
62     AVFilterContext *ret;
63     char *name, *args;
64
65     name = filter;
66     if((args = strchr(filter, '='))) {
67         /* ensure we at least have a name */
68         if(args == filter)
69             return NULL;
70
71         *args ++ = 0;
72     }
73
74     av_log(NULL, AV_LOG_INFO, "creating filter \"%s\" with args \"%s\"\n",
75            name, args ? args : "(none)");
76
77     if((ret = avfilter_create_by_name(name, NULL))) {
78         if(avfilter_init_filter(ret, args)) {
79             av_log(NULL, AV_LOG_ERROR, "error initializing filter!\n");
80             avfilter_destroy(ret);
81             ret = NULL;
82         }
83     } else av_log(NULL, AV_LOG_ERROR, "error creating filter!\n");
84
85     return ret;
86 }
87
88 int avfilter_graph_load_chain(AVFilterGraph *graph,
89                               unsigned count, char **filter_list,
90                               AVFilterContext **first, AVFilterContext **last)
91 {
92     unsigned i;
93     AVFilterContext *filters[2] = {NULL,NULL};
94
95     for(i = 0; i < count; i ++) {
96         if(!(filters[1] = create_filter_with_args(filter_list[i])))
97             goto fail;
98         if(i == 0) {
99             if(first) *first = filters[1];
100         } else {
101             if(avfilter_link(filters[0], 0, filters[1], 0)) {
102                 av_log(NULL, AV_LOG_ERROR, "error linking filters!\n");
103                 goto fail;
104             }
105         }
106         avfilter_graph_add_filter(graph, filters[1]);
107         filters[0] = filters[1];
108     }
109
110     if(last) *last = filters[1];
111     return 0;
112
113 fail:
114     destroy_graph_filters(graph);
115     if(first) *first = NULL;
116     if(last)  *last  = NULL;
117     return -1;
118 }
119