+typedef struct {
+ AVFilterContext *graph;
+} GraphLinkContext;
+
+static int link_init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+ GraphLinkContext *linkctx = ctx->priv;
+ linkctx->graph = opaque;
+ return !opaque;
+}
+
+/**
+ * Given the link between the dummy filter and an internal filter whose input
+ * is being exported outside the graph, this returns the externally visible
+ * link.
+ */
+static inline AVFilterLink *get_extern_input_link(AVFilterLink *link)
+{
+ GraphLinkContext *lctx = link->src->priv;
+ return lctx->graph->inputs[link->srcpad];
+}
+
+/** request a frame from a filter providing input to the graph */
+static int link_in_request_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_extern_input_link(link);
+
+ if(!link2)
+ return -1;
+ return avfilter_request_frame(link2);
+}
+
+
+static int link_in_poll_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_extern_input_link(link);
+ if(!link2)
+ return -1;
+ return avfilter_poll_frame(link2);
+}
+
+static int link_in_config_props(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_extern_input_link(link);
+ int (*config_props)(AVFilterLink *);
+ int ret;
+
+ if(!link2)
+ return -1;
+ if(!(config_props = link2->src->output_pads[link2->srcpad].config_props))
+ config_props = avfilter_default_config_output_link;
+ ret = config_props(link2);
+
+ link->w = link2->w;
+ link->h = link2->h;
+
+ return ret;
+}
+
+/**
+ * Given the link between the dummy filter and an internal filter whose input
+ * is being exported outside the graph, this returns the externally visible
+ * link.
+ */
+static inline AVFilterLink *get_extern_output_link(AVFilterLink *link)
+{
+ GraphLinkContext *lctx = link->dst->priv;
+ return lctx->graph->outputs[link->dstpad];
+}
+
+static int link_out_config_props(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_extern_output_link(link);
+
+ if(!link2)
+ return 0;
+
+ link2->w = link->w;
+ link2->h = link->h;
+
+ return 0;
+}
+
+static void link_out_start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+ AVFilterLink *link2 = get_extern_output_link(link);
+
+ if(!link2)
+ avfilter_unref_pic(picref);
+ else
+ avfilter_start_frame(link2, picref);
+}
+
+static void link_out_end_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_extern_output_link(link);
+
+ if(link2)
+ avfilter_end_frame(link2);
+}
+
+static AVFilterPicRef *link_out_get_video_buffer(AVFilterLink *link, int perms)
+{
+ AVFilterLink *link2 = get_extern_output_link(link);
+
+ if(!link2)
+ return NULL;
+ else
+ return avfilter_get_video_buffer(link2, perms);
+}
+
+static void link_out_draw_slice(AVFilterLink *link, int y, int height)
+{
+ AVFilterLink *link2 = get_extern_output_link(link);
+
+ if(link2)
+ avfilter_draw_slice(link2, y, height);
+}
+
+/** dummy filter used to help export filters pads outside the graph */
+static AVFilter vf_graph_dummy =
+{
+ .name = "graph_dummy",
+
+ .priv_size = sizeof(GraphLinkContext),
+
+ .init = link_init,
+
+ .inputs = (AVFilterPad[]) {{ .name = NULL, }},
+ .outputs = (AVFilterPad[]) {{ .name = NULL, }},
+};
+
+static AVFilterLink *get_intern_input_link(AVFilterLink *link)
+{
+ GraphContext *graph = link->dst->priv;
+ return graph->link_filter_in->outputs[link->dstpad];
+}
+
+static void graph_in_start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+ AVFilterLink *link2 = get_intern_input_link(link);
+ if(link2)
+ avfilter_start_frame(link2, picref);
+}
+
+static void graph_in_end_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_intern_input_link(link);
+ if(link2)
+ avfilter_end_frame(link2);
+}
+
+static AVFilterPicRef *graph_in_get_video_buffer(AVFilterLink *link, int perms)
+{
+ AVFilterLink *link2 = get_intern_input_link(link);
+ if(link2)
+ return avfilter_get_video_buffer(link2, perms);
+ return NULL;
+}
+
+static void graph_in_draw_slice(AVFilterLink *link, int y, int height)
+{
+ AVFilterLink *link2 = get_intern_input_link(link);
+ if(link2)
+ avfilter_draw_slice(link2, y, height);
+}
+
+static int graph_in_config_props(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_intern_input_link(link);
+ int (*config_props)(AVFilterLink *);
+ int ret;
+
+ if(!link2)
+ return -1;
+
+ /* copy link properties over to the dummy internal link */
+ link2->w = link->w;
+ link2->h = link->h;
+ link2->format = link->format;
+
+ if(!(config_props = link2->dst->input_pads[link2->dstpad].config_props))
+ return 0; /* FIXME? */
+ //config_props = avfilter_default_config_input_link;
+ if(!(ret = config_props(link2)))
+ link2->init_state = AVLINK_INIT;
+ else
+ link2->init_state = AVLINK_STARTINIT;
+
+ return ret;
+}
+
+static AVFilterLink *get_intern_output_link(AVFilterLink *link)
+{
+ GraphContext *graph = link->src->priv;
+ return graph->link_filter_out->inputs[link->srcpad];
+}
+
+static int graph_out_request_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_intern_output_link(link);
+
+ if(link2)
+ return avfilter_request_frame(link2);
+ return -1;
+}
+
+static int graph_out_poll_frame(AVFilterLink *link)
+{
+ AVFilterLink *link2 = get_intern_output_link(link);
+
+ if(!link2)
+ return -1;
+
+ return avfilter_poll_frame(link2);
+}
+
+static int graph_out_config_props(AVFilterLink *link)
+{
+ GraphContext *graph = link->src->priv;
+ AVFilterLink *link2 = graph->link_filter_out->inputs[link->srcpad];
+ int ret;
+
+ if((ret = avfilter_config_links(graph->link_filter_out)))
+ return ret;
+
+ if(!link2)
+ return 0;
+
+ link->w = link2->w;
+ link->h = link2->h;
+ link->format = link2->format;
+
+ return 0;
+}
+
+static int add_graph_input(AVFilterContext *gctx, AVFilterContext *filt, unsigned idx,
+ char *name)
+{
+ GraphContext *graph = gctx->priv;
+
+ AVFilterPad graph_inpad =
+ {
+ .name = name,
+ .type = CODEC_TYPE_VIDEO,
+ .start_frame = graph_in_start_frame,
+ .end_frame = graph_in_end_frame,
+ .get_video_buffer = graph_in_get_video_buffer,
+ .draw_slice = graph_in_draw_slice,
+ .config_props = graph_in_config_props,
+ /* XXX */
+ };
+ AVFilterPad dummy_outpad =
+ {
+ .name = NULL, /* FIXME? */
+ .type = CODEC_TYPE_VIDEO,
+ .request_frame = link_in_request_frame,
+ .poll_frame = link_in_poll_frame,
+ .config_props = link_in_config_props,
+ };
+
+ avfilter_insert_inpad (gctx, gctx->input_count, &graph_inpad);
+ avfilter_insert_outpad(graph->link_filter_in, graph->link_filter_in->output_count,
+ &dummy_outpad);
+ return avfilter_link(graph->link_filter_in,
+ graph->link_filter_in->output_count-1, filt, idx);
+}
+
+static int add_graph_output(AVFilterContext *gctx, AVFilterContext *filt, unsigned idx,
+ char *name)
+{
+ GraphContext *graph = gctx->priv;
+
+ AVFilterPad graph_outpad =
+ {
+ .name = name,
+ .type = CODEC_TYPE_VIDEO,
+ .request_frame = graph_out_request_frame,
+ .poll_frame = graph_out_poll_frame,
+ .config_props = graph_out_config_props,
+ };
+ AVFilterPad dummy_inpad =
+ {
+ .name = NULL, /* FIXME? */
+ .type = CODEC_TYPE_VIDEO,
+ .start_frame = link_out_start_frame,
+ .end_frame = link_out_end_frame,
+ .draw_slice = link_out_draw_slice,
+ .get_video_buffer = link_out_get_video_buffer,
+ .config_props = link_out_config_props,
+ };
+
+ avfilter_insert_outpad(gctx, gctx->output_count, &graph_outpad);
+ avfilter_insert_inpad (graph->link_filter_out, graph->link_filter_out->input_count,
+ &dummy_inpad);
+ return avfilter_link(filt, idx, graph->link_filter_out,
+ graph->link_filter_out->input_count-1);
+}
+