[FFmpeg-devel] [PATCH] fftools: Fix MediaCodec on Android15+

[FFmpeg-devel] [PATCH] fftools: Fix MediaCodec on Android15+

[xaionaro--- via ffmpeg-devel]

From: Dmitrii Okunev <xaionaro@dx.center>

On Android15+ MediaCodec HAL backend was switched from HIDL to AIDL.
As a result, MediaCodec operations started to hang, see:

    https://github.com/termux/termux-packages/issues/21264

To fix that it is necessary to initialize binder thread pool.

Signed-off-by: Dmitrii Okunev <xaionaro@dx.center>
---
 fftools/Makefile         |   3 +
 fftools/android_binder.c | 131 +++++++++++++++++++++++++++++++++++++++
 fftools/android_binder.h |  31 +++++++++
 fftools/ffmpeg.c         |   4 ++
 fftools/ffmpeg.h         |   1 +
 fftools/ffplay.c         |   5 ++
 6 files changed, 175 insertions(+)
 create mode 100644 fftools/android_binder.c
 create mode 100644 fftools/android_binder.h

diff --git a/fftools/Makefile b/fftools/Makefile
index bdb44fc5ce..00d1c503f3 100644
--- a/fftools/Makefile
+++ b/fftools/Makefile
@@ -53,6 +53,9 @@ OBJS-ffprobe +=                       \
 
 OBJS-ffplay += fftools/ffplay_renderer.o
 
+OBJS-ffmpeg-$(CONFIG_MEDIACODEC) += fftools/android_binder.o
+OBJS-ffplay-$(CONFIG_MEDIACODEC) += fftools/android_binder.o
+
 define DOFFTOOL
 OBJS-$(1) += fftools/cmdutils.o fftools/opt_common.o fftools/$(1).o $(OBJS-$(1)-yes)
 ifdef HAVE_GNU_WINDRES
diff --git a/fftools/android_binder.c b/fftools/android_binder.c
new file mode 100644
index 0000000000..e16c7f4b31
--- /dev/null
+++ b/fftools/android_binder.c
@@ -0,0 +1,131 @@
+/*
+ * Android Binder handler
+ *
+ * Copyright (c) 2025 Dmitrii Okunev
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+#if defined(__ANDROID__)
+
+#include <dlfcn.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "config.h"
+#include "libavutil/log.h"
+#include "android_binder.h"
+
+#define DEFAULT_THREAD_POOL_SIZE 4
+#define MAX_THREAD_POOL_SIZE     256
+
+static unsigned get_thread_pool_size(void)
+{
+    const char *tps_str = getenv("FFMPEG_ANDROID_BINDER_THREAD_POOL_SIZE");
+    if (tps_str == NULL || !*tps_str) {
+        av_log(NULL, AV_LOG_DEBUG,
+               "android/binder: FFMPEG_ANDROID_BINDER_THREAD_POOL_SIZE not set, using default %u\n",
+               DEFAULT_THREAD_POOL_SIZE);
+        return DEFAULT_THREAD_POOL_SIZE;
+    }
+
+    errno = 0;
+    unsigned long thread_pool_size = strtoul(tps_str, NULL, 10);
+    if (errno != 0 || thread_pool_size <= 0
+        || thread_pool_size > UINT32_MAX) {
+        av_log(NULL, AV_LOG_ERROR,
+               "android/binder: invalid value of FFMPEG_ANDROID_BINDER_THREAD_POOL_SIZE: '%s' (errno: %d), using the default one, instead: %u\n",
+               tps_str, errno, DEFAULT_THREAD_POOL_SIZE);
+        return DEFAULT_THREAD_POOL_SIZE;
+    }
+
+    if (thread_pool_size > MAX_THREAD_POOL_SIZE) {
+        av_log(NULL, AV_LOG_WARNING,
+               "android/binder: too large FFMPEG_ANDROID_BINDER_THREAD_POOL_SIZE: '%s', clamping to %d\n",
+               tps_str, MAX_THREAD_POOL_SIZE);
+        thread_pool_size = MAX_THREAD_POOL_SIZE;
+    }
+
+    av_log(NULL, AV_LOG_DEBUG,
+           "android/binder: thread pool size: %lu\n", thread_pool_size);
+    return (unsigned) thread_pool_size;
+}
+
+static void *dlopen_libbinder_ndk(void)
+{
+    /*
+     * To make ffmpeg builds reusable at different Android versions we intentionally
+     * avoid including linking with libbinder_ndk.so at the link time. Instead, we
+     * resolve the symbols at runtime using dlopen()/dlsym().
+     *
+     * See also: https://source.android.com/docs/core/architecture/aidl/aidl-backends
+     */
+
+    void *h = dlopen("libbinder_ndk.so", RTLD_NOW | RTLD_LOCAL);
+    if (h != NULL)
+        return h;
+
+    av_log(NULL, AV_LOG_VERBOSE,
+           "android/binder: libbinder_ndk.so not found; skipping binder threadpool init\n");
+    return NULL;
+}
+
+void android_binder_threadpool_init(void)
+{
+    typedef int (*set_thread_pool_max_fn)(uint32_t);
+    typedef void (*start_thread_pool_fn)(void);
+
+    set_thread_pool_max_fn set_thread_pool_max = NULL;
+    start_thread_pool_fn start_thread_pool = NULL;
+
+    void *h = dlopen_libbinder_ndk();
+    if (h == NULL) {
+        return;
+    }
+
+    unsigned thead_pool_size = get_thread_pool_size();
+
+    set_thread_pool_max =
+        (set_thread_pool_max_fn) dlsym(h,
+                                       "ABinderProcess_setThreadPoolMaxThreadCount");
+    start_thread_pool =
+        (start_thread_pool_fn) dlsym(h, "ABinderProcess_startThreadPool");
+
+    if (start_thread_pool == NULL) {
+        av_log(NULL, AV_LOG_VERBOSE,
+               "android/binder: ABinderProcess_startThreadPool not found; skipping threadpool init\n");
+        return;
+    }
+
+    if (set_thread_pool_max != NULL) {
+        int ok = set_thread_pool_max(thead_pool_size);
+        av_log(NULL, AV_LOG_DEBUG,
+               "android/binder: ABinderProcess_setThreadPoolMaxThreadCount(%u) => %s\n",
+               thead_pool_size, ok ? "ok" : "fail");
+    } else {
+        av_log(NULL, AV_LOG_DEBUG,
+               "android/binder: ABinderProcess_setThreadPoolMaxThreadCount is unavailable; using the library default\n");
+    }
+
+    start_thread_pool();
+    av_log(NULL, AV_LOG_DEBUG,
+           "android/binder: ABinderProcess_startThreadPool() called\n");
+}
+
+#endif                          /* __ANDROID__ */
diff --git a/fftools/android_binder.h b/fftools/android_binder.h
new file mode 100644
index 0000000000..56c487fe4c
--- /dev/null
+++ b/fftools/android_binder.h
@@ -0,0 +1,31 @@
+/*
+ * Android Binder handler
+ *
+ * Copyright (c) 2025 Dmitrii Okunev
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef FFTOOLS_ANDROID_BINDER_H
+#define FFTOOLS_ANDROID_BINDER_H
+
+/**
+ * Initialize Android Binder thread pool.
+ */
+void android_binder_threadpool_init(void);
+
+#endif                          // FFTOOLS_ANDROID_BINDER_H
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 444d027c15..7b250ac5da 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -1019,6 +1019,10 @@ int main(int argc, char **argv)
         goto finish;
     }
 
+#if defined(__ANDROID__)
+    android_binder_threadpool_init();
+#endif
+
     current_time = ti = get_benchmark_time_stamps();
     ret = transcode(sch);
     if (ret >= 0 && do_benchmark) {
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index cc2ea1a56e..6c6ef0509a 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -26,6 +26,7 @@
 #include <stdio.h>
 #include <signal.h>
 
+#include "android_binder.h"
 #include "cmdutils.h"
 #include "ffmpeg_sched.h"
 #include "sync_queue.h"
diff --git a/fftools/ffplay.c b/fftools/ffplay.c
index dc2627521e..14fde65f27 100644
--- a/fftools/ffplay.c
+++ b/fftools/ffplay.c
@@ -54,6 +54,7 @@
 #include <SDL.h>
 #include <SDL_thread.h>
 
+#include "android_binder.h"
 #include "cmdutils.h"
 #include "ffplay_renderer.h"
 #include "opt_common.h"
@@ -3892,6 +3893,10 @@ int main(int argc, char **argv)
         }
     }
 
+#if defined(__ANDROID__)
+    android_binder_threadpool_init();
+#endif
+
     is = stream_open(input_filename, file_iformat);
     if (!is) {
         av_log(NULL, AV_LOG_FATAL, "Failed to initialize VideoState!\n");
-- 
2.48.1

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