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ffmpeg/libavfilter/graphparser.c

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/*
* filter graph parser
* copyright (c) 2008 Vitor Sessak
* copyright (c) 2007 Bobby Bingham
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <ctype.h>
#include <string.h>
#include "avfilter.h"
#include "avfiltergraph.h"
/**
* For use in av_log
*/
static const char *log_name(void *p)
{
return "Filter parser";
}
static const AVClass filter_parser_class = {
"Filter parser",
log_name
};
static const AVClass *log_ctx = &filter_parser_class;
static AVFilterContext *create_filter(AVFilterGraph *ctx, int index,
char *name, char *args)
{
AVFilterContext *filt;
AVFilter *filterdef;
char tmp[20];
snprintf(tmp, 20, "%d", index);
if(!(filterdef = avfilter_get_by_name(name))) {
av_log(&log_ctx, AV_LOG_ERROR,
"no such filter: '%s'\n", name);
return NULL;
}
if(!(filt = avfilter_open(filterdef, tmp))) {
av_log(&log_ctx, AV_LOG_ERROR,
"error creating filter '%s'\n", name);
return NULL;
}
if (avfilter_graph_add_filter(ctx, filt) < 0)
return NULL;
if(avfilter_init_filter(filt, args, NULL)) {
av_log(&log_ctx, AV_LOG_ERROR,
"error initializing filter '%s' with args '%s'\n", name, args);
return NULL;
}
return filt;
}
static int link_filter(AVFilterContext *src, int srcpad,
AVFilterContext *dst, int dstpad)
{
if(avfilter_link(src, srcpad, dst, dstpad)) {
av_log(&log_ctx, AV_LOG_ERROR,
"cannot create the link %s:%d -> %s:%d\n",
src->filter->name, srcpad, dst->filter->name, dstpad);
return -1;
}
return 0;
}
static void consume_whitespace(const char **buf)
{
*buf += strspn(*buf, " \n\t");
}
/**
* Copy the first size bytes of input string to a null-terminated string,
* removing any control character. Ex: "aaa'bb'c\'c\\" -> "aaabbc'c\"
*/
static void copy_unquoted(char *out, const char *in, int size)
{
int i;
for (i=0; i < size; i++) {
if (in[i] == '\'')
continue;
else if (in[i] == '\\') {
if (i+1 == size) {
*out = 0;
return;
}
i++;
}
*out++ = in[i];
}
*out=0;
}
/**
* Consumes a string from *buf.
* @return a copy of the consumed string, which should be free'd after use
*/
static char *consume_string(const char **buf)
{
const char *start;
char *ret;
int size;
consume_whitespace(buf);
if (!(**buf))
return av_mallocz(1);
start = *buf;
while(1) {
*buf += strcspn(*buf, " ()=,'\\");
if (**buf == '\\')
*buf+=2;
else
break;
}
if (**buf == '\'') {
const char *p = *buf;
do {
p++;
p = strchr(p, '\'');
} while (p && p[-1] == '\\');
if (p)
*buf = p + 1;
else
*buf += strlen(*buf); // Move the pointer to the null end byte
}
size = *buf - start + 1;
ret = av_malloc(size);
copy_unquoted(ret, start, size-1);
return ret;
}
/**
* Parse "(linkname)"
* @arg name a pointer (that need to be free'd after use) to the name between
* parenthesis
*/
static void parse_link_name(const char **buf, char **name)
{
(*buf)++;
*name = consume_string(buf);
if (!*name[0])
goto fail;
if (*(*buf)++ != ')')
goto fail;
return;
fail:
av_freep(name);
av_log(&log_ctx, AV_LOG_ERROR, "Could not parse link name!\n");
}
/**
* Parse "filter=params"
* @arg name a pointer (that need to be free'd after use) to the name of the
* filter
* @arg ars a pointer (that need to be free'd after use) to the args of the
* filter
*/
static AVFilterContext *parse_filter(const char **buf, AVFilterGraph *graph, int index)
{
char *name, *opts;
name = consume_string(buf);
if (**buf == '=') {
(*buf)++;
opts = consume_string(buf);
} else {
opts = NULL;
}
return create_filter(graph, index, name, opts);
}
enum LinkType {
LinkTypeIn,
LinkTypeOut,
};
/**
* A linked-list of the inputs/outputs of the filter chain.
*/
typedef struct AVFilterInOut {
enum LinkType type;
char *name;
AVFilterContext *instance;
int pad_idx;
struct AVFilterInOut *next;
} AVFilterInOut;
static void free_inout(AVFilterInOut *head)
{
while (head) {
AVFilterInOut *next;
next = head->next;
av_free(head);
head = next;
}
}
/**
* Parse "(a1)(link2) ... (etc)"
*/
static int parse_inouts(const char **buf, AVFilterInOut **inout, int firstpad,
enum LinkType type, AVFilterContext *instance)
{
int pad = firstpad;
while (**buf == '(') {
AVFilterInOut *inoutn = av_malloc(sizeof(AVFilterInOut));
parse_link_name(buf, &inoutn->name);
inoutn->type = type;
inoutn->instance = instance;
inoutn->pad_idx = pad++;
inoutn->next = *inout;
*inout = inoutn;
}
return pad;
}
static const char *skip_inouts(const char *buf)
{
while (*buf == '(') {
buf += strcspn(buf, ")");
buf++;
}
return buf;
}
/**
* Parse a string describing a filter graph.
*/
int avfilter_graph_parse_chain(AVFilterGraph *graph, const char *filters, AVFilterContext *in, int inpad, AVFilterContext *out, int outpad)
{
AVFilterInOut *inout=NULL;
AVFilterInOut *head=NULL;
int index = 0;
char chr = 0;
int pad = 0;
int has_out = 0;
AVFilterContext *last_filt = NULL;
consume_whitespace(&filters);
do {
AVFilterContext *filter;
int oldpad = pad;
const char *inouts = filters;
// We need to parse the inputs of the filter after we create it, so
// skip it by now
filters = skip_inouts(filters);
if (!(filter = parse_filter(&filters, graph, index)))
goto fail;
pad = parse_inouts(&inouts, &inout, chr == ',', LinkTypeIn, filter);
// If the first filter has an input and none was given, it is
// implicitly the input of the whole graph.
if (pad == 0 && graph->filters[graph->filter_count-1]->input_count == 1) {
if(link_filter(in, inpad, filter, 0))
goto fail;
}
if(chr == ',') {
if (link_filter(last_filt, oldpad, filter, 0) < 0)
goto fail;
}
pad = parse_inouts(&filters, &inout, 0, LinkTypeOut, filter);
chr = *filters++;
index++;
last_filt = filter;
} while (chr == ',' || chr == ';');
head = inout;
for (; inout != NULL; inout = inout->next) {
if (inout->instance == NULL)
continue; // Already processed
if (!strcmp(inout->name, "in")) {
if(link_filter(in, inpad, inout->instance, inout->pad_idx))
goto fail;
} else if (!strcmp(inout->name, "out")) {
has_out = 1;
if(link_filter(inout->instance, inout->pad_idx, out, outpad))
goto fail;
} else {
AVFilterInOut *p, *src, *dst;
for (p = inout->next;
p && strcmp(p->name,inout->name); p = p->next);
if (!p) {
av_log(&log_ctx, AV_LOG_ERROR, "Unmatched link: %s.\n",
inout->name);
goto fail;
}
if (p->type == LinkTypeIn && inout->type == LinkTypeOut) {
src = inout;
dst = p;
} else if (p->type == LinkTypeOut && inout->type == LinkTypeIn) {
src = p;
dst = inout;
} else {
av_log(&log_ctx, AV_LOG_ERROR, "Two links named '%s' are either both input or both output\n",
inout->name);
goto fail;
}
if (link_filter(src->instance, src->pad_idx, dst->instance, dst->pad_idx) < 0)
goto fail;
src->instance = NULL;
dst->instance = NULL;
}
}
free_inout(head);
if (!has_out) {
if(link_filter(last_filt, pad, out, outpad))
goto fail;
}
return 0;
fail:
free_inout(head);
avfilter_destroy_graph(graph);
return -1;
}
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