--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libavutil/threadmessage.h	Wed Nov 16 11:16:33 2016 +0200
@@ -0,0 +1,91 @@
+/*
+ * 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 AVUTIL_THREADMESSAGE_H
+#define AVUTIL_THREADMESSAGE_H
+
+typedef struct AVThreadMessageQueue AVThreadMessageQueue;
+
+typedef enum AVThreadMessageFlags {
+
+    /**
+     * Perform non-blocking operation.
+     * If this flag is set, send and recv operations are non-blocking and
+     * return AVERROR(EAGAIN) immediately if they can not proceed.
+     */
+    AV_THREAD_MESSAGE_NONBLOCK = 1,
+
+} AVThreadMessageFlags;
+
+/**
+ * Allocate a new message queue.
+ *
+ * @param mq      pointer to the message queue
+ * @param nelem   maximum number of elements in the queue
+ * @param elsize  size of each element in the queue
+ * @return  >=0 for success; <0 for error, in particular AVERROR(ENOSYS) if
+ *          lavu was built without thread support
+ */
+int av_thread_message_queue_alloc(AVThreadMessageQueue **mq,
+                                  unsigned nelem,
+                                  unsigned elsize);
+
+/**
+ * Free a message queue.
+ *
+ * The message queue must no longer be in use by another thread.
+ */
+void av_thread_message_queue_free(AVThreadMessageQueue **mq);
+
+/**
+ * Send a message on the queue.
+ */
+int av_thread_message_queue_send(AVThreadMessageQueue *mq,
+                                 void *msg,
+                                 unsigned flags);
+
+/**
+ * Receive a message from the queue.
+ */
+int av_thread_message_queue_recv(AVThreadMessageQueue *mq,
+                                 void *msg,
+                                 unsigned flags);
+
+/**
+ * Set the sending error code.
+ *
+ * If the error code is set to non-zero, av_thread_message_queue_recv() will
+ * return it immediately when there are no longer available messages.
+ * Conventional values, such as AVERROR_EOF or AVERROR(EAGAIN), can be used
+ * to cause the receiving thread to stop or suspend its operation.
+ */
+void av_thread_message_queue_set_err_send(AVThreadMessageQueue *mq,
+                                          int err);
+
+/**
+ * Set the receiving error code.
+ *
+ * If the error code is set to non-zero, av_thread_message_queue_send() will
+ * return it immediately. Conventional values, such as AVERROR_EOF or
+ * AVERROR(EAGAIN), can be used to cause the sending thread to stop or
+ * suspend its operation.
+ */
+void av_thread_message_queue_set_err_recv(AVThreadMessageQueue *mq,
+                                          int err);
+
+#endif /* AVUTIL_THREADMESSAGE_H */