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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 Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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 "libavutil/avstring.h"
#include "avfilter.h"
#include "avfiltergraph.h"
#define WHITESPACES " \n\t"
/**
* Link two filters together.
*
* @see avfilter_link()
*/
static int link_filter(AVFilterContext *src, int srcpad,
AVFilterContext *dst, int dstpad,
void *log_ctx)
{
int ret;
if ((ret = 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 ret;
}
return 0;
}
/**
* Parse the name of a link, which has the format "[linkname]".
*
* @return a pointer (that need to be freed after use) to the name
* between parenthesis
*/
static char *parse_link_name(const char **buf, void *log_ctx)
{
const char *start = *buf;
char *name;
(*buf)++;
name = av_get_token(buf, "]");
if (!name[0]) {
av_log(log_ctx, AV_LOG_ERROR,
"Bad (empty?) label found in the following: \"%s\".\n", start);
goto fail;
}
if (*(*buf)++ != ']') {
av_log(log_ctx, AV_LOG_ERROR,
"Mismatched '[' found in the following: \"%s\".\n", start);
fail:
av_freep(&name);
}
return name;
}
/**
* Create an instance of a filter, initialize and insert it in the
* filtergraph in *ctx.
*
* @param filt_ctx put here a filter context in case of successful creation and configuration, NULL otherwise.
* @param ctx the filtergraph context
* @param index an index which is supposed to be unique for each filter instance added to the filtergraph
* @param filt_name the name of the filter to create
* @param args the arguments provided to the filter during its initialization
* @param log_ctx the log context to use
* @return 0 in case of success, a negative AVERROR code otherwise
*/
static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,
const char *filt_name, const char *args, void *log_ctx)
{
AVFilter *filt;
char inst_name[30];
char tmp_args[256];
int ret;
snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);
filt = avfilter_get_by_name(filt_name);
if (!filt) {
av_log(log_ctx, AV_LOG_ERROR,
"No such filter: '%s'\n", filt_name);
return AVERROR(EINVAL);
}
ret = avfilter_open(filt_ctx, filt, inst_name);
if (!*filt_ctx) {
av_log(log_ctx, AV_LOG_ERROR,
"Error creating filter '%s'\n", filt_name);
return ret;
}
if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {
avfilter_free(*filt_ctx);
return ret;
}
if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")) {
snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
args, ctx->scale_sws_opts);
args = tmp_args;
}
if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {
av_log(log_ctx, AV_LOG_ERROR,
"Error initializing filter '%s' with args '%s'\n", filt_name, args);
return ret;
}
return 0;
}
/**
* Parse a string of the form FILTER_NAME[=PARAMS], and create a
* corresponding filter instance which is added to graph with
* create_filter().
*
* @param filt_ctx Pointer that is set to the created and configured filter
* context on success, set to NULL on failure.
* @param filt_ctx put here a pointer to the created filter context on
* success, NULL otherwise
* @param buf pointer to the buffer to parse, *buf will be updated to
* point to the char next after the parsed string
* @param index an index which is assigned to the created filter
* instance, and which is supposed to be unique for each filter
* instance added to the filtergraph
* @return 0 in case of success, a negative AVERROR code otherwise
*/
static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,
int index, void *log_ctx)
{
char *opts = NULL;
char *name = av_get_token(buf, "=,;[\n");
int ret;
if (**buf == '=') {
(*buf)++;
opts = av_get_token(buf, "[],;\n");
}
ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);
av_free(name);
av_free(opts);
return ret;
}
AVFilterInOut *avfilter_inout_alloc(void)
{
return av_mallocz(sizeof(AVFilterInOut));
}
void avfilter_inout_free(AVFilterInOut **inout)
{
while (*inout) {
AVFilterInOut *next = (*inout)->next;
av_freep(&(*inout)->name);
av_freep(inout);
*inout = next;
}
}
static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
{
AVFilterInOut *ret;
while (*links && (!(*links)->name || strcmp((*links)->name, label)))
links = &((*links)->next);
ret = *links;
if (ret) {
*links = ret->next;
ret->next = NULL;
}
return ret;
}
static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
{
element->next = *inouts;
*inouts = element;
}
static void append_inout(AVFilterInOut **inouts, AVFilterInOut **element)
{
while (*inouts && (*inouts)->next)
inouts = &((*inouts)->next);
if (!*inouts)
*inouts = *element;
else
(*inouts)->next = *element;
*element = NULL;
}
static int link_filter_inouts(AVFilterContext *filt_ctx,
AVFilterInOut **curr_inputs,
AVFilterInOut **open_inputs, void *log_ctx)
{
int pad, ret;
for (pad = 0; pad < filt_ctx->nb_inputs; pad++) {
AVFilterInOut *p = *curr_inputs;
if (p) {
*curr_inputs = (*curr_inputs)->next;
p->next = NULL;
} else if (!(p = av_mallocz(sizeof(*p))))
return AVERROR(ENOMEM);
if (p->filter_ctx) {
if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)
return ret;
av_free(p->name);
av_free(p);
} else {
p->filter_ctx = filt_ctx;
p->pad_idx = pad;
append_inout(open_inputs, &p);
}
}
if (*curr_inputs) {
av_log(log_ctx, AV_LOG_ERROR,
"Too many inputs specified for the \"%s\" filter.\n",
filt_ctx->filter->name);
return AVERROR(EINVAL);
}
pad = filt_ctx->nb_outputs;
while (pad--) {
AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));
if (!currlinkn)
return AVERROR(ENOMEM);
currlinkn->filter_ctx = filt_ctx;
currlinkn->pad_idx = pad;
insert_inout(curr_inputs, currlinkn);
}
return 0;
}
static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,
AVFilterInOut **open_outputs, void *log_ctx)
{
AVFilterInOut *parsed_inputs = NULL;
int pad = 0;
while (**buf == '[') {
char *name = parse_link_name(buf, log_ctx);
AVFilterInOut *match;
if (!name)
return AVERROR(EINVAL);
/* First check if the label is not in the open_outputs list */
match = extract_inout(name, open_outputs);
if (match) {
av_free(name);
} else {
/* Not in the list, so add it as an input */
if (!(match = av_mallocz(sizeof(AVFilterInOut))))
return AVERROR(ENOMEM);
match->name = name;
match->pad_idx = pad;
}
append_inout(&parsed_inputs, &match);
*buf += strspn(*buf, WHITESPACES);
pad++;
}
append_inout(&parsed_inputs, curr_inputs);
*curr_inputs = parsed_inputs;
return pad;
}
static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
AVFilterInOut **open_inputs,
AVFilterInOut **open_outputs, void *log_ctx)
{
int ret, pad = 0;
while (**buf == '[') {
char *name = parse_link_name(buf, log_ctx);
AVFilterInOut *match;
AVFilterInOut *input = *curr_inputs;
if (!input) {
av_log(log_ctx, AV_LOG_ERROR,
"No output pad can be associated to link label '%s'.\n",
name);
return AVERROR(EINVAL);
}
*curr_inputs = (*curr_inputs)->next;
if (!name)
return AVERROR(EINVAL);
/* First check if the label is not in the open_inputs list */
match = extract_inout(name, open_inputs);
if (match) {
if ((ret = link_filter(input->filter_ctx, input->pad_idx,
match->filter_ctx, match->pad_idx, log_ctx)) < 0)
return ret;
av_free(match->name);
av_free(name);
av_free(match);
av_free(input);
} else {
/* Not in the list, so add the first input as a open_output */
input->name = name;
insert_inout(open_outputs, input);
}
*buf += strspn(*buf, WHITESPACES);
pad++;
}
return pad;
}
static int parse_sws_flags(const char **buf, AVFilterGraph *graph)
{
char *p = strchr(*buf, ';');
if (strncmp(*buf, "sws_flags=", 10))
return 0;
if (!p) {
av_log(graph, AV_LOG_ERROR, "sws_flags not terminated with ';'.\n");
return AVERROR(EINVAL);
}
*buf += 4; // keep the 'flags=' part
av_freep(&graph->scale_sws_opts);
if (!(graph->scale_sws_opts = av_mallocz(p - *buf + 1)))
return AVERROR(ENOMEM);
av_strlcpy(graph->scale_sws_opts, *buf, p - *buf + 1);
*buf = p + 1;
return 0;
}
int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
AVFilterInOut **inputs,
AVFilterInOut **outputs)
{
int index = 0, ret;
char chr = 0;
AVFilterInOut *curr_inputs = NULL, *open_inputs = NULL, *open_outputs = NULL;
filters += strspn(filters, WHITESPACES);
if ((ret = parse_sws_flags(&filters, graph)) < 0)
goto fail;
do {
AVFilterContext *filter;
filters += strspn(filters, WHITESPACES);
if ((ret = parse_inputs(&filters, &curr_inputs, &open_outputs, graph)) < 0)
goto fail;
if ((ret = parse_filter(&filter, &filters, graph, index, graph)) < 0)
goto fail;
if ((ret = link_filter_inouts(filter, &curr_inputs, &open_inputs, graph)) < 0)
goto fail;
if ((ret = parse_outputs(&filters, &curr_inputs, &open_inputs, &open_outputs,
graph)) < 0)
goto fail;
filters += strspn(filters, WHITESPACES);
chr = *filters++;
if (chr == ';' && curr_inputs)
append_inout(&open_outputs, &curr_inputs);
index++;
} while (chr == ',' || chr == ';');
if (chr) {
av_log(graph, AV_LOG_ERROR,
"Unable to parse graph description substring: \"%s\"\n",
filters - 1);
ret = AVERROR(EINVAL);
goto fail;
}
append_inout(&open_outputs, &curr_inputs);
*inputs = open_inputs;
*outputs = open_outputs;
return 0;
fail:
for (; graph->filter_count > 0; graph->filter_count--)
avfilter_free(graph->filters[graph->filter_count - 1]);
av_freep(&graph->filters);
avfilter_inout_free(&open_inputs);
avfilter_inout_free(&open_outputs);
avfilter_inout_free(&curr_inputs);
*inputs = NULL;
*outputs = NULL;
return ret;
}
int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
AVFilterInOut *open_inputs,
AVFilterInOut *open_outputs, void *log_ctx)
{
int ret;
AVFilterInOut *cur, *match, *inputs = NULL, *outputs = NULL;
if ((ret = avfilter_graph_parse2(graph, filters, &inputs, &outputs)) < 0)
goto fail;
/* First input can be omitted if it is "[in]" */
if (inputs && !inputs->name)
inputs->name = av_strdup("in");
for (cur = inputs; cur; cur = cur->next) {
if (!cur->name) {
av_log(log_ctx, AV_LOG_ERROR,
"Not enough inputs specified for the \"%s\" filter.\n",
cur->filter_ctx->filter->name);
ret = AVERROR(EINVAL);
goto fail;
}
if (!(match = extract_inout(cur->name, &open_outputs)))
continue;
ret = avfilter_link(match->filter_ctx, match->pad_idx,
cur->filter_ctx, cur->pad_idx);
avfilter_inout_free(&match);
if (ret < 0)
goto fail;
}
/* Last output can be omitted if it is "[out]" */
if (outputs && !outputs->name)
outputs->name = av_strdup("out");
for (cur = outputs; cur; cur = cur->next) {
if (!cur->name) {
av_log(log_ctx, AV_LOG_ERROR,
"Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
filters);
ret = AVERROR(EINVAL);
goto fail;
}
if (!(match = extract_inout(cur->name, &open_inputs)))
continue;
ret = avfilter_link(cur->filter_ctx, cur->pad_idx,
match->filter_ctx, match->pad_idx);
avfilter_inout_free(&match);
if (ret < 0)
goto fail;
}
fail:
if (ret < 0) {
for (; graph->filter_count > 0; graph->filter_count--)
avfilter_free(graph->filters[graph->filter_count - 1]);
av_freep(&graph->filters);
}
avfilter_inout_free(&inputs);
avfilter_inout_free(&outputs);
avfilter_inout_free(&open_inputs);
avfilter_inout_free(&open_outputs);
return ret;
}
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