Statistics
| Branch: | Revision:

ffmpeg / libavfilter / graphparser.c @ eb79c528

History | View | Annotate | Download (11.6 KB)

1
/*
2
 * filter graph parser
3
 * Copyright (c) 2008 Vitor Sessak
4
 * Copyright (c) 2007 Bobby Bingham
5
 *
6
 * This file is part of FFmpeg.
7
 *
8
 * FFmpeg is free software; you can redistribute it and/or
9
 * modify it under the terms of the GNU Lesser General Public
10
 * License as published by the Free Software Foundation; either
11
 * version 2.1 of the License, or (at your option) any later version.
12
 *
13
 * FFmpeg is distributed in the hope that it will be useful,
14
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16
 * Lesser General Public License for more details.
17
 *
18
 * You should have received a copy of the GNU Lesser General Public
19
 * License along with FFmpeg; if not, write to the Free Software
20
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21
 */
22

    
23
#include <ctype.h>
24
#include <string.h>
25

    
26
#include "libavutil/avstring.h"
27
#include "avfilter.h"
28
#include "avfiltergraph.h"
29

    
30
#define WHITESPACES " \n\t"
31

    
32
/**
33
 * Link two filters together.
34
 *
35
 * @see avfilter_link()
36
 */
37
static int link_filter(AVFilterContext *src, int srcpad,
38
                       AVFilterContext *dst, int dstpad,
39
                       AVClass *log_ctx)
40
{
41
    int ret;
42
    if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {
43
        av_log(log_ctx, AV_LOG_ERROR,
44
               "Cannot create the link %s:%d -> %s:%d\n",
45
               src->filter->name, srcpad, dst->filter->name, dstpad);
46
        return ret;
47
    }
48

    
49
    return 0;
50
}
51

    
52
/**
53
 * Parse the name of a link, which has the format "[linkname]".
54
 *
55
 * @return a pointer (that need to be freed after use) to the name
56
 * between parenthesis
57
 */
58
static char *parse_link_name(const char **buf, AVClass *log_ctx)
59
{
60
    const char *start = *buf;
61
    char *name;
62
    (*buf)++;
63

    
64
    name = av_get_token(buf, "]");
65

    
66
    if (!name[0]) {
67
        av_log(log_ctx, AV_LOG_ERROR,
68
               "Bad (empty?) label found in the following: \"%s\".\n", start);
69
        goto fail;
70
    }
71

    
72
    if (*(*buf)++ != ']') {
73
        av_log(log_ctx, AV_LOG_ERROR,
74
               "Mismatched '[' found in the following: \"%s\".\n", start);
75
    fail:
76
        av_freep(&name);
77
    }
78

    
79
    return name;
80
}
81

    
82
/**
83
 * Create an instance of a filter, initialize and insert it in the
84
 * filtergraph in *ctx.
85
 *
86
 * @param ctx the filtergraph context
87
 * @param put here a filter context in case of successful creation and configuration, NULL otherwise.
88
 * @param index an index which is supposed to be unique for each filter instance added to the filtergraph
89
 * @param filt_name the name of the filter to create
90
 * @param args the arguments provided to the filter during its initialization
91
 * @param log_ctx the log context to use
92
 * @return 0 in case of success, a negative AVERROR code otherwise
93
 */
94
static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
95
                         const char *filt_name, const char *args, AVClass *log_ctx)
96
{
97
    AVFilter *filt;
98
    char inst_name[30];
99
    char tmp_args[256];
100
    int ret;
101

    
102
    snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);
103

    
104
    filt = avfilter_get_by_name(filt_name);
105

    
106
    if (!filt) {
107
        av_log(log_ctx, AV_LOG_ERROR,
108
               "No such filter: '%s'\n", filt_name);
109
        return AVERROR(EINVAL);
110
    }
111

    
112
    ret = avfilter_open(filt_ctx, filt, inst_name);
113
    if (!*filt_ctx) {
114
        av_log(log_ctx, AV_LOG_ERROR,
115
               "Error creating filter '%s'\n", filt_name);
116
        return ret;
117
    }
118

    
119
    if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {
120
        avfilter_free(*filt_ctx);
121
        return ret;
122
    }
123

    
124
    if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")) {
125
        snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
126
                 args, ctx->scale_sws_opts);
127
        args = tmp_args;
128
    }
129

    
130
    if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {
131
        av_log(log_ctx, AV_LOG_ERROR,
132
               "Error initializing filter '%s' with args '%s'\n", filt_name, args);
133
        return ret;
134
    }
135

    
136
    return 0;
137
}
138

    
139
/**
140
 * Parse a string of the form FILTER_NAME[=PARAMS], and create a
141
 * corresponding filter instance which is added to graph with
142
 * create_filter().
143
 *
144
 * @param filt_ctx put here a pointer to the created filter context on
145
 * success, NULL otherwise
146
 * @param buf pointer to the buffer to parse, *buf will be updated to
147
 * point to the char next after the parsed string
148
 * @param index an index which is assigned to the created filter
149
 * instance, and which is supposed to be unique for each filter
150
 * instance added to the filtergraph
151
 * @return 0 in case of success, a negative AVERROR code otherwise
152
 */
153
static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
154
                        int index, AVClass *log_ctx)
155
{
156
    char *opts = NULL;
157
    char *name = av_get_token(buf, "=,;[\n");
158
    int ret;
159

    
160
    if (**buf == '=') {
161
        (*buf)++;
162
        opts = av_get_token(buf, "[],;\n");
163
    }
164

    
165
    ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
166
    av_free(name);
167
    av_free(opts);
168
    return ret;
169
}
170

    
171
static void free_inout(AVFilterInOut *head)
172
{
173
    while (head) {
174
        AVFilterInOut *next = head->next;
175
        av_free(head->name);
176
        av_free(head);
177
        head = next;
178
    }
179
}
180

    
181
static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
182
{
183
    AVFilterInOut *ret;
184

    
185
    while (*links && strcmp((*links)->name, label))
186
        links = &((*links)->next);
187

    
188
    ret = *links;
189

    
190
    if (ret)
191
        *links = ret->next;
192

    
193
    return ret;
194
}
195

    
196
static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
197
{
198
    element->next = *inouts;
199
    *inouts = element;
200
}
201

    
202
static int link_filter_inouts(AVFilterContext *filt_ctx,
203
                              AVFilterInOut **curr_inputs,
204
                              AVFilterInOut **open_inputs, AVClass *log_ctx)
205
{
206
    int pad = filt_ctx->input_count, ret;
207

    
208
    while (pad--) {
209
        AVFilterInOut *p = *curr_inputs;
210
        if (!p) {
211
            av_log(log_ctx, AV_LOG_ERROR,
212
                   "Not enough inputs specified for the \"%s\" filter.\n",
213
                   filt_ctx->filter->name);
214
            return AVERROR(EINVAL);
215
        }
216

    
217
        *curr_inputs = (*curr_inputs)->next;
218

    
219
        if (p->filter_ctx) {
220
            if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)
221
                return ret;
222
            av_free(p->name);
223
            av_free(p);
224
        } else {
225
            p->filter_ctx = filt_ctx;
226
            p->pad_idx = pad;
227
            insert_inout(open_inputs, p);
228
        }
229
    }
230

    
231
    if (*curr_inputs) {
232
        av_log(log_ctx, AV_LOG_ERROR,
233
               "Too many inputs specified for the \"%s\" filter.\n",
234
               filt_ctx->filter->name);
235
        return AVERROR(EINVAL);
236
    }
237

    
238
    pad = filt_ctx->output_count;
239
    while (pad--) {
240
        AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
241
        if (!currlinkn)
242
            return AVERROR(ENOMEM);
243
        currlinkn->filter_ctx  = filt_ctx;
244
        currlinkn->pad_idx = pad;
245
        insert_inout(curr_inputs, currlinkn);
246
    }
247

    
248
    return 0;
249
}
250

    
251
static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
252
                        AVFilterInOut **open_outputs, AVClass *log_ctx)
253
{
254
    int pad = 0;
255

    
256
    while (**buf == '[') {
257
        char *name = parse_link_name(buf, log_ctx);
258
        AVFilterInOut *match;
259

    
260
        if (!name)
261
            return AVERROR(EINVAL);
262

    
263
        /* First check if the label is not in the open_outputs list */
264
        match = extract_inout(name, open_outputs);
265

    
266
        if (match) {
267
            av_free(name);
268
        } else {
269
            /* Not in the list, so add it as an input */
270
            if (!(match = av_mallocz(sizeof(AVFilterInOut))))
271
                return AVERROR(ENOMEM);
272
            match->name    = name;
273
            match->pad_idx = pad;
274
        }
275

    
276
        insert_inout(curr_inputs, match);
277

    
278
        *buf += strspn(*buf, WHITESPACES);
279
        pad++;
280
    }
281

    
282
    return pad;
283
}
284

    
285
static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
286
                         AVFilterInOut **open_inputs,
287
                         AVFilterInOut **open_outputs, AVClass *log_ctx)
288
{
289
    int ret, pad = 0;
290

    
291
    while (**buf == '[') {
292
        char *name = parse_link_name(buf, log_ctx);
293
        AVFilterInOut *match;
294

    
295
        AVFilterInOut *input = *curr_inputs;
296
        if (!input) {
297
            av_log(log_ctx, AV_LOG_ERROR,
298
                   "No output pad can be associated to link label '%s'.\n",
299
                   name);
300
            return AVERROR(EINVAL);
301
        }
302
        *curr_inputs = (*curr_inputs)->next;
303

    
304
        if (!name)
305
            return AVERROR(EINVAL);
306

    
307
        /* First check if the label is not in the open_inputs list */
308
        match = extract_inout(name, open_inputs);
309

    
310
        if (match) {
311
            if ((ret = link_filter(input->filter_ctx, input->pad_idx,
312
                                   match->filter_ctx, match->pad_idx, log_ctx)) < 0)
313
                return ret;
314
            av_free(match->name);
315
            av_free(name);
316
            av_free(match);
317
            av_free(input);
318
        } else {
319
            /* Not in the list, so add the first input as a open_output */
320
            input->name = name;
321
            insert_inout(open_outputs, input);
322
        }
323
        *buf += strspn(*buf, WHITESPACES);
324
        pad++;
325
    }
326

    
327
    return pad;
328
}
329

    
330
int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
331
                         AVFilterInOut *open_inputs,
332
                         AVFilterInOut *open_outputs, AVClass *log_ctx)
333
{
334
    int index = 0, ret;
335
    char chr = 0;
336

    
337
    AVFilterInOut *curr_inputs = NULL;
338

    
339
    do {
340
        AVFilterContext *filter;
341
        const char *filterchain = filters;
342
        filters += strspn(filters, WHITESPACES);
343

    
344
        if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, log_ctx)) < 0)
345
            goto fail;
346

    
347
        if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)
348
            goto fail;
349

    
350
        if (filter->input_count == 1 && !curr_inputs && !index) {
351
            /* First input can be omitted if it is "[in]" */
352
            const char *tmp = "[in]";
353
            if ((ret = parse_inputs(&tmp, &curr_inputs, &open_outputs, log_ctx)) < 0)
354
                goto fail;
355
        }
356

    
357
        if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, log_ctx)) < 0)
358
            goto fail;
359

    
360
        if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
361
                                 log_ctx)) < 0)
362
            goto fail;
363

    
364
        filters += strspn(filters, WHITESPACES);
365
        chr = *filters++;
366

    
367
        if (chr == ';' && curr_inputs) {
368
            av_log(log_ctx, AV_LOG_ERROR,
369
                   "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
370
                   filterchain);
371
            ret = AVERROR(EINVAL);
372
            goto fail;
373
        }
374
        index++;
375
    } while (chr == ',' || chr == ';');
376

    
377
    if (chr) {
378
        av_log(log_ctx, AV_LOG_ERROR,
379
               "Unable to parse graph description substring: \"%s\"\n",
380
               filters - 1);
381
        ret = AVERROR(EINVAL);
382
        goto fail;
383
    }
384

    
385
    if (open_inputs && !strcmp(open_inputs->name, "out") && curr_inputs) {
386
        /* Last output can be omitted if it is "[out]" */
387
        const char *tmp = "[out]";
388
        if ((ret = parse_outputs(&tmp, &curr_inputs, &open_inputs, &open_outputs,
389
                                 log_ctx)) < 0)
390
            goto fail;
391
    }
392

    
393
    return 0;
394

    
395
 fail:
396
    for (; graph->filter_count > 0; graph->filter_count--)
397
        avfilter_free(graph->filters[graph->filter_count - 1]);
398
    av_freep(&graph->filters);
399
    free_inout(open_inputs);
400
    free_inout(open_outputs);
401
    free_inout(curr_inputs);
402
    return ret;
403
}