lavfi: make filter_frame non-recursive.

A lot of changes happen at the same time:

- Add a framequeue fifo to AVFilterLink.

- split AVFilterLink.status into status_in and status_out: requires
  changes to the few filters and programs that use it directly
  (f_interleave, split, filtfmts).

- Add a field ready to AVFilterContext, marking when the filter is ready
  and its activation priority.

- Add flags to mark blocked links.

- Change ff_filter_frame() to enqueue the frame.

- Change all filtering functions to update the ready field and the
  blocked flags.

- Update ff_filter_graph_run_once() to use the ready field.

- buffersrc: always push the frame immediately.

libavfilter/avfilter.h

@@ -368,6 +368,13 @@ struct AVFilterContext {
      * Overrides global number of threads set per filter graph.
      */
     int nb_threads;
+
+    /**
+     * Ready status of the filter.
+     * A non-0 value means that the filter needs activating;
+     * a higher value suggests a more urgent activation.
+     */
+    unsigned ready;
 };
 
 /**
@@ -508,18 +515,6 @@ struct AVFilterLink {
      */
     int max_samples;
 
-    /**
-     * Link status.
-     * If not zero, all attempts of filter_frame or request_frame
-     * will fail with the corresponding code, and if necessary the reference
-     * will be destroyed.
-     * If request_frame returns an error, the status is set on the
-     * corresponding link.
-     * It can be set also be set by either the source or the destination
-     * filter.
-     */
-    int status;
-
     /**
      * Number of channels.
      */
@@ -540,13 +535,6 @@ struct AVFilterLink {
      */
     void *video_frame_pool;
 
-    /**
-     * True if a frame is currently wanted on the input of this filter.
-     * Set when ff_request_frame() is called by the output,
-     * cleared when the request is handled or forwarded.
-     */
-    int frame_wanted_in;
-
     /**
      * True if a frame is currently wanted on the output of this filter.
      * Set when ff_request_frame() is called by the output,
@@ -559,6 +547,51 @@ struct AVFilterLink {
      * AVHWFramesContext describing the frames.
      */
     AVBufferRef *hw_frames_ctx;
+
+#ifndef FF_INTERNAL_FIELDS
+
+    /**
+     * Internal structure members.
+     * The fields below this limit are internal for libavfilter's use
+     * and must in no way be accessed by applications.
+     */
+    char reserved[0xF000];
+
+#else /* FF_INTERNAL_FIELDS */
+
+    /**
+     * Queue of frames waiting to be filtered.
+     */
+    FFFrameQueue fifo;
+
+    /**
+     * If set, the source filter can not generate a frame as is.
+     * The goal is to avoid repeatedly calling the request_frame() method on
+     * the same link.
+     */
+    int frame_blocked_in;
+
+    /**
+     * Link input status.
+     * If not zero, all attempts of filter_frame will fail with the
+     * corresponding code.
+     */
+    int status_in;
+
+    /**
+     * Timestamp of the input status change.
+     */
+    int64_t status_in_pts;
+
+    /**
+     * Link output status.
+     * If not zero, all attempts of request_frame will fail with the
+     * corresponding code.
+     */
+    int status_out;
+
+#endif /* FF_INTERNAL_FIELDS */
+
 };
 
 /**

libavfilter/avfiltergraph.c

@@ -32,6 +32,9 @@
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 
+#define FF_INTERNAL_FIELDS 1
+#include "framequeue.h"
+
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
@@ -87,6 +90,7 @@ AVFilterGraph *avfilter_graph_alloc(void)
 
     ret->av_class = &filtergraph_class;
     av_opt_set_defaults(ret);
+    ff_framequeue_global_init(&ret->internal->frame_queues);
 
     return ret;
 }
@@ -1377,10 +1381,10 @@ void ff_avfilter_graph_update_heap(AVFilterGraph *graph, AVFilterLink *link)
     heap_bubble_down(graph, link, link->age_index);
 }
 
-
 int avfilter_graph_request_oldest(AVFilterGraph *graph)
 {
     AVFilterLink *oldest = graph->sink_links[0];
+    int64_t frame_count;
     int r;
 
     while (graph->sink_links_count) {
@@ -1400,7 +1404,8 @@ int avfilter_graph_request_oldest(AVFilterGraph *graph)
     if (!graph->sink_links_count)
         return AVERROR_EOF;
     av_assert1(oldest->age_index >= 0);
-    while (oldest->frame_wanted_out) {
+    frame_count = oldest->frame_count_out;
+    while (frame_count == oldest->frame_count_out) {
         r = ff_filter_graph_run_once(graph);
         if (r < 0)
             return r;
@@ -1408,41 +1413,17 @@ int avfilter_graph_request_oldest(AVFilterGraph *graph)
     return 0;
 }
 
-static AVFilterLink *graph_run_once_find_filter(AVFilterGraph *graph)
-{
-    unsigned i, j;
-    AVFilterContext *f;
-
-    /* TODO: replace scanning the graph with a priority list */
-    for (i = 0; i < graph->nb_filters; i++) {
-        f = graph->filters[i];
-        for (j = 0; j < f->nb_outputs; j++)
-            if (f->outputs[j]->frame_wanted_in)
-                return f->outputs[j];
-    }
-    for (i = 0; i < graph->nb_filters; i++) {
-        f = graph->filters[i];
-        for (j = 0; j < f->nb_outputs; j++)
-            if (f->outputs[j]->frame_wanted_out)
-                return f->outputs[j];
-    }
-    return NULL;
-}
-
 int ff_filter_graph_run_once(AVFilterGraph *graph)
 {
-    AVFilterLink *link;
-    int ret;
-
-    link = graph_run_once_find_filter(graph);
-    if (!link) {
-        av_log(NULL, AV_LOG_WARNING, "Useless run of a filter graph\n");
+    AVFilterContext *filter;
+    unsigned i;
+
+    av_assert0(graph->nb_filters);
+    filter = graph->filters[0];
+    for (i = 1; i < graph->nb_filters; i++)
+        if (graph->filters[i]->ready > filter->ready)
+            filter = graph->filters[i];
+    if (!filter->ready)
         return AVERROR(EAGAIN);
-    }
-    ret = ff_request_frame_to_filter(link);
-    if (ret == AVERROR_EOF)
-        /* local EOF will be forwarded through request_frame() /
-           set_status() until it reaches the sink */
-        ret = 0;
-    return ret < 0 ? ret : 1;
+    return ff_filter_activate(filter);
 }

libavfilter/buffersink.c

@@ -31,6 +31,9 @@
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 
+#define FF_INTERNAL_FIELDS 1
+#include "framequeue.h"
+
 #include "audio.h"
 #include "avfilter.h"
 #include "buffersink.h"
@@ -129,18 +132,26 @@ int attribute_align_arg av_buffersink_get_frame_flags(AVFilterContext *ctx, AVFr
 {
     BufferSinkContext *buf = ctx->priv;
     AVFilterLink *inlink = ctx->inputs[0];
-    int ret;
+    int peek_in_framequeue = 0, ret;
+    int64_t frame_count;
     AVFrame *cur_frame;
 
     /* no picref available, fetch it from the filterchain */
     while (!av_fifo_size(buf->fifo)) {
-        if (inlink->status)
-            return inlink->status;
-        if (flags & AV_BUFFERSINK_FLAG_NO_REQUEST)
+        /* if peek_in_framequeue is true later, then ff_request_frame() and
+           the ff_filter_graph_run_once() loop will take a frame from it and
+           move it to the internal fifo, ending the global loop */
+        av_assert0(!peek_in_framequeue);
+        if (inlink->status_out)
+            return inlink->status_out;
+        peek_in_framequeue = ff_framequeue_queued_frames(&inlink->fifo) &&
+                             ff_framequeue_queued_samples(&inlink->fifo) >= inlink->min_samples;
+        if ((flags & AV_BUFFERSINK_FLAG_NO_REQUEST) && !peek_in_framequeue)
             return AVERROR(EAGAIN);
         if ((ret = ff_request_frame(inlink)) < 0)
             return ret;
-        while (inlink->frame_wanted_out) {
+        frame_count = inlink->frame_count_out;
+        while (frame_count == inlink->frame_count_out) {
             ret = ff_filter_graph_run_once(ctx->graph);
             if (ret < 0)
                 return ret;

libavfilter/buffersrc.c

@@ -184,6 +184,7 @@ static int av_buffersrc_add_frame_internal(AVFilterContext *ctx,
 
     if (!frame) {
         s->eof = 1;
+        ff_avfilter_link_set_in_status(ctx->outputs[0], AVERROR_EOF, AV_NOPTS_VALUE);
         return 0;
     } else if (s->eof)
         return AVERROR(EINVAL);
@@ -235,9 +236,8 @@ static int av_buffersrc_add_frame_internal(AVFilterContext *ctx,
         return ret;
     }
 
-    if ((flags & AV_BUFFERSRC_FLAG_PUSH))
-        if ((ret = ctx->output_pads[0].request_frame(ctx->outputs[0])) < 0)
-            return ret;
+    if ((ret = ctx->output_pads[0].request_frame(ctx->outputs[0])) < 0)
+        return ret;
 
     return 0;
 }

libavfilter/f_interleave.c

@@ -26,6 +26,10 @@
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/opt.h"
+
+#define FF_INTERNAL_FIELDS 1
+#include "framequeue.h"
+
 #include "avfilter.h"
 #include "bufferqueue.h"
 #include "formats.h"
@@ -59,7 +63,7 @@ inline static int push_frame(AVFilterContext *ctx)
     for (i = 0; i < ctx->nb_inputs; i++) {
         struct FFBufQueue *q = &s->queues[i];
 
-        if (!q->available && !ctx->inputs[i]->status)
+        if (!q->available && !ctx->inputs[i]->status_out)
             return 0;
         if (q->available) {
             frame = ff_bufqueue_peek(q, 0);
@@ -190,7 +194,7 @@ static int request_frame(AVFilterLink *outlink)
     int i, ret;
 
     for (i = 0; i < ctx->nb_inputs; i++) {
-        if (!s->queues[i].available && !ctx->inputs[i]->status) {
+        if (!s->queues[i].available && !ctx->inputs[i]->status_out) {
             ret = ff_request_frame(ctx->inputs[i]);
             if (ret != AVERROR_EOF)
                 return ret;

libavfilter/internal.h

@@ -29,6 +29,7 @@
 #include "avfiltergraph.h"
 #include "formats.h"
 #include "framepool.h"
+#include "framequeue.h"
 #include "thread.h"
 #include "version.h"
 #include "video.h"
@@ -147,6 +148,7 @@ struct AVFilterPad {
 struct AVFilterGraphInternal {
     void *thread;
     avfilter_execute_func *thread_execute;
+    FFFrameQueueGlobal frame_queues;
 };
 
 struct AVFilterInternal {
@@ -336,6 +338,8 @@ int ff_request_frame(AVFilterLink *link);
 
 int ff_request_frame_to_filter(AVFilterLink *link);
 
+int ff_filter_frame_to_filter(AVFilterLink *link);
+
 #define AVFILTER_DEFINE_CLASS(fname)            \
     static const AVClass fname##_class = {      \
         .class_name = #fname,                   \
@@ -376,6 +380,8 @@ int ff_filter_frame(AVFilterLink *link, AVFrame *frame);
  */
 AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name);
 
+int ff_filter_activate(AVFilterContext *filter);
+
 /**
  * Remove a filter from a graph;
  */

libavfilter/split.c

@@ -30,6 +30,9 @@
 #include "libavutil/mem.h"
 #include "libavutil/opt.h"
 
+#define FF_INTERNAL_FIELDS 1
+#include "framequeue.h"
+
 #include "avfilter.h"
 #include "audio.h"
 #include "formats.h"
@@ -78,7 +81,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
     for (i = 0; i < ctx->nb_outputs; i++) {
         AVFrame *buf_out;
 
-        if (ctx->outputs[i]->status)
+        if (ctx->outputs[i]->status_in)
             continue;
         buf_out = av_frame_clone(frame);
         if (!buf_out) {

libavfilter/tests/filtfmts.c

@@ -25,6 +25,9 @@
 #include "libavutil/pixdesc.h"
 #include "libavutil/samplefmt.h"
 
+#define FF_INTERNAL_FIELDS 1
+#include "libavfilter/framequeue.h"
+
 #include "libavfilter/avfilter.h"
 #include "libavfilter/formats.h"
 

libavfilter/vf_extractplanes.c

@@ -22,6 +22,10 @@
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
+
+#define FF_INTERNAL_FIELDS 1
+#include "libavfilter/framequeue.h"
+
 #include "avfilter.h"
 #include "drawutils.h"
 #include "internal.h"
@@ -283,7 +287,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
         const int idx = s->map[i];
         AVFrame *out;
 
-        if (outlink->status)
+        if (outlink->status_in)
             continue;
 
         out = ff_get_video_buffer(outlink, outlink->w, outlink->h);