From cce85642c90097e235086e65ddfc0f41c5f90608 Mon Sep 17 00:00:00 2001
From: James Almer <jamrial@gmail.com>
Date: Sat, 18 Oct 2025 20:08:49 -0300
Subject: [PATCH] fftools/ffmpeg_sched: add a function to remove a filtergraph
 from the scheduler

For the purpose of merging streams in a stream group, a filtergraph can't be
created once we know it will be used. Therefore, allow filtergraphs to be
removed from the scheduler after being added.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 fftools/ffmpeg_sched.c | 23 +++++++++++++++++++++++
 fftools/ffmpeg_sched.h |  2 ++
 2 files changed, 25 insertions(+)

diff --git a/fftools/ffmpeg_sched.c b/fftools/ffmpeg_sched.c
index d08f4a061d..ed85bb16de 100644
--- a/fftools/ffmpeg_sched.c
+++ b/fftools/ffmpeg_sched.c
@@ -405,6 +405,9 @@ static int task_start(SchTask *task)
 {
     int ret;
 
+    if (!task->parent)
+        return 0;
+
     av_log(task->func_arg, AV_LOG_VERBOSE, "Starting thread...\n");
 
     av_assert0(!task->thread_running);
@@ -454,6 +457,23 @@ static int64_t trailing_dts(const Scheduler *sch, int count_finished)
     return min_dts == INT64_MAX ? AV_NOPTS_VALUE : min_dts;
 }
 
+void sch_remove_filtergraph(Scheduler *sch, int idx)
+{
+    SchFilterGraph *fg = &sch->filters[idx];
+
+    av_assert0(!fg->task.thread_running);
+    memset(&fg->task, 0, sizeof(fg->task));
+
+    tq_free(&fg->queue);
+
+    av_freep(&fg->inputs);
+    fg->nb_inputs = 0;
+    av_freep(&fg->outputs);
+    fg->nb_outputs = 0;
+
+    fg->task_exited = 1;
+}
+
 void sch_free(Scheduler **psch)
 {
     Scheduler *sch = *psch;
@@ -2630,6 +2650,9 @@ static int task_stop(Scheduler *sch, SchTask *task)
     int ret;
     void *thread_ret;
 
+    if (!task->parent)
+        return 0;
+
     if (!task->thread_running)
         return task_cleanup(sch, task->node);
 
diff --git a/fftools/ffmpeg_sched.h b/fftools/ffmpeg_sched.h
index 0c01f558e4..2cf3034437 100644
--- a/fftools/ffmpeg_sched.h
+++ b/fftools/ffmpeg_sched.h
@@ -205,6 +205,8 @@ int sch_add_dec_output(Scheduler *sch, unsigned dec_idx);
 int sch_add_filtergraph(Scheduler *sch, unsigned nb_inputs, unsigned nb_outputs,
                         SchThreadFunc func, void *ctx);
 
+void sch_remove_filtergraph(Scheduler *sch, int idx);
+
 /**
  * Add a muxer to the scheduler.
  *