[FFmpeg-devel] [PATCH] avfilter/split: switch to activate()

[Paul B Mahol <onemda@gmail.com>]

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---

Fix possible hangs if (a)split filter is used in graph and one of outputs ends
earlier than others.
Then filter may never receive EOF from input provided by (a)split filter.

See ticket #9152 for commands how to reproduce issue.

---
 libavfilter/split.c | 68 +++++++++++++++++++++++++++++++++------------
 1 file changed, 51 insertions(+), 17 deletions(-)

diff --git a/libavfilter/split.c b/libavfilter/split.c
index 6b9b656708..98b51f976e 100644
--- a/libavfilter/split.c
+++ b/libavfilter/split.c
@@ -63,28 +63,62 @@ static av_cold int split_init(AVFilterContext *ctx)
     return 0;
 }
 
-static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+static int activate(AVFilterContext *ctx)
 {
-    AVFilterContext *ctx = inlink->dst;
-    int i, ret = AVERROR_EOF;
+    AVFilterLink *inlink = ctx->inputs[0];
+    AVFrame *in;
+    int status, ret;
+    int64_t pts;
 
-    for (i = 0; i < ctx->nb_outputs; i++) {
-        AVFrame *buf_out;
+    for (int i = 0; i < ctx->nb_outputs; i++) {
+        FF_FILTER_FORWARD_STATUS_BACK_ALL(ctx->outputs[i], ctx);
+    }
 
-        if (ff_outlink_get_status(ctx->outputs[i]))
-            continue;
-        buf_out = av_frame_clone(frame);
-        if (!buf_out) {
-            ret = AVERROR(ENOMEM);
-            break;
+    ret = ff_inlink_consume_frame(inlink, &in);
+    if (ret < 0)
+        return ret;
+    if (ret > 0) {
+        for (int i = 0; i < ctx->nb_outputs; i++) {
+            AVFrame *buf_out;
+
+            if (ff_outlink_get_status(ctx->outputs[i]))
+                continue;
+            buf_out = av_frame_clone(in);
+            if (!buf_out) {
+                ret = AVERROR(ENOMEM);
+                break;
+            }
+
+            ret = ff_filter_frame(ctx->outputs[i], buf_out);
+            if (ret < 0)
+                break;
         }
 
-        ret = ff_filter_frame(ctx->outputs[i], buf_out);
+        av_frame_free(&in);
         if (ret < 0)
-            break;
+            return ret;
+    }
+
+    if (ff_inlink_acknowledge_status(inlink, &status, &pts)) {
+        for (int i = 0; i < ctx->nb_outputs; i++) {
+            if (ff_outlink_get_status(ctx->outputs[i]))
+                continue;
+            ff_outlink_set_status(ctx->outputs[i], status, pts);
+        }
+        return 0;
     }
-    av_frame_free(&frame);
-    return ret;
+
+    for (int i = 0; i < ctx->nb_outputs; i++) {
+        if (ff_outlink_get_status(ctx->outputs[i]))
+            continue;
+
+        if (ff_outlink_frame_wanted(ctx->outputs[i])) {
+            ff_inlink_request_frame(inlink);
+            return 0;
+        }
+    }
+
+    return FFERROR_NOT_READY;
 }
 
 #define OFFSET(x) offsetof(SplitContext, x)
@@ -100,7 +134,6 @@ static const AVFilterPad avfilter_vf_split_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
-        .filter_frame = filter_frame,
     },
 };
 
@@ -110,6 +143,7 @@ const AVFilter ff_vf_split = {
     .priv_size   = sizeof(SplitContext),
     .priv_class  = &split_class,
     .init        = split_init,
+    .activate    = activate,
     FILTER_INPUTS(avfilter_vf_split_inputs),
     .outputs     = NULL,
     .flags       = AVFILTER_FLAG_DYNAMIC_OUTPUTS | AVFILTER_FLAG_METADATA_ONLY,
@@ -119,7 +153,6 @@ static const AVFilterPad avfilter_af_asplit_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
-        .filter_frame = filter_frame,
     },
 };
 
@@ -129,6 +162,7 @@ const AVFilter ff_af_asplit = {
     .priv_class  = &split_class,
     .priv_size   = sizeof(SplitContext),
     .init        = split_init,
+    .activate    = activate,
     FILTER_INPUTS(avfilter_af_asplit_inputs),
     .outputs     = NULL,
     .flags       = AVFILTER_FLAG_DYNAMIC_OUTPUTS | AVFILTER_FLAG_METADATA_ONLY,
-- 
2.33.0

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