diff mbox

[FFmpeg-devel] libavformat: Add ZeroMQ as a protocol option

Message ID 20190730204401.kmixoh36gwhamr7k@manj
State New
Headers show

Commit Message

Andriy Gelman July 30, 2019, 8:44 p.m. UTC
Hello, 

I've been looking for a way to stream to multiple clients without using a
multicast destination address or an external server. 

I believe ZeroMQ, which is a lightweight asynchronous messaging library, is a
possible option. It is already part of ffmpeg and can be used to
forward messages to filters in a filtergraph.

I've put together an initial patch which adds ZeroMQ as a protocol option. 

To run an example, you will need to compile with the --enable-libzmq option. 

One streaming instance can be started with:
$ ./ffmpeg -i /dev/video0 -vcodec libx264 -tune zerolatency -f mpegts zmq:tcp://127.0.0.1:5555

Multiple clients can then connect with:
$ ./ffplay zmq:tcp://127.0.0.1:5555

I would be happy to maintain the code. 

Thanks,
Andriy
From 366f705945f9b2c40158730ec18ac9259bca2695 Mon Sep 17 00:00:00 2001
From: Andriy Gelman <andriy.gelman@gmail.com>
Date: Tue, 30 Jul 2019 14:39:32 -0400
Subject: [PATCH] libavformat: Add ZeroMQ as a protocol option

Currently multiple clients are only supported by using a
multicast destination address. An alternative is to stream to a server
which re-distributes the content.

This commit adds ZeroMQ as a protocol option, which allows
multiple clients to connect to a single ffmpeg instance.
---
 configure               |   2 +
 doc/general.texi        |   1 +
 doc/protocols.texi      |  37 +++++++++
 libavformat/Makefile    |   1 +
 libavformat/libzmq.c    | 162 ++++++++++++++++++++++++++++++++++++++++
 libavformat/protocols.c |   1 +
 6 files changed, 204 insertions(+)
 create mode 100644 libavformat/libzmq.c
diff mbox

Patch

diff --git a/configure b/configure
index 5a4f507246..4515341b06 100755
--- a/configure
+++ b/configure
@@ -3400,6 +3400,8 @@  libsrt_protocol_deps="libsrt"
 libsrt_protocol_select="network"
 libssh_protocol_deps="libssh"
 libtls_conflict="openssl gnutls mbedtls"
+libzmq_protocol_deps="libzmq"
+libzmq_protocol_select="network"
 
 # filters
 afftdn_filter_deps="avcodec"
diff --git a/doc/general.texi b/doc/general.texi
index 3c0c803449..b8e063268c 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -1329,6 +1329,7 @@  performance on systems without hardware floating point support).
 @item TCP          @tab X
 @item TLS          @tab X
 @item UDP          @tab X
+@item ZMQ          @tab E
 @end multitable
 
 @code{X} means that the protocol is supported.
diff --git a/doc/protocols.texi b/doc/protocols.texi
index 3e4e7af3d4..04d0fa8101 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -1728,4 +1728,41 @@  Timeout in ms.
 Create the Unix socket in listening mode.
 @end table
 
+@section libzmq
+
+ZeroMQ asynchronous messaging library.
+
+This library supports unicast streaming to multiple clients without relying on
+an external server.
+
+The required syntax for streaming or connecting to a stream is:
+@example
+zmq:tcp://hostname:port
+@end example
+
+Example:
+Create a localhost stream on port 5555:
+@example
+ffmpeg -re -i input -f mpegts zmq:tcp://127.0.0.1:5555
+@end example
+
+Multiple clients may connect and view the stream using:
+@example
+ffplay zmq:tcp://127.0.0.1:5555
+@end example
+
+@table @option
+@item zmq_timeout
+Set timeout (milliseconds) in the socket message receive call.
+By default it is set to 0. For more details see the timeout option
+in @url{http://api.zeromq.org/3-2:zmq-poll}.
+@end table
+
+The order with which the streaming and connecting instances start does not
+matter. This is handled by the ZeroMQ library.
+
+ffmpeg must be compiled with the --enable-libzmq option to support
+this protocol. See the compilation guide @url{https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu}
+for an example on how this option may be set.
+
 @c man end PROTOCOLS
diff --git a/libavformat/Makefile b/libavformat/Makefile
index a434b005a4..4a535429b7 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -631,6 +631,7 @@  OBJS-$(CONFIG_LIBRTMPTE_PROTOCOL)        += librtmp.o
 OBJS-$(CONFIG_LIBSMBCLIENT_PROTOCOL)     += libsmbclient.o
 OBJS-$(CONFIG_LIBSRT_PROTOCOL)           += libsrt.o
 OBJS-$(CONFIG_LIBSSH_PROTOCOL)           += libssh.o
+OBJS-$(CONFIG_LIBZMQ_PROTOCOL) 			 		 += libzmq.o
 
 # libavdevice dependencies
 OBJS-$(CONFIG_IEC61883_INDEV)            += dv.o
diff --git a/libavformat/libzmq.c b/libavformat/libzmq.c
new file mode 100644
index 0000000000..a7ef7fe77c
--- /dev/null
+++ b/libavformat/libzmq.c
@@ -0,0 +1,162 @@ 
+/*
+ * ZMQ URLProtocol
+ *
+ * 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
+ */
+
+#include <zmq.h>
+#include "url.h"
+#include "network.h"
+#include "libavutil/avstring.h"
+#include "libavutil/opt.h"
+
+typedef struct ZMQContext {
+    const AVClass *class;
+    void *context;
+    void *socket;
+    unsigned int timeout; /*blocking timeout during zmq poll in milliseconds */
+} ZMQContext;
+
+static const AVOption options[] = {
+    { "zmq_timeout", "Set timeout (milliseconds) in the socket message receive call. By default it is set to 0.", offsetof(ZMQContext, timeout), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+    { NULL }
+};
+
+static int ff_zmq_open(URLContext *h, const char *uri, int flags)
+{
+    int ret;
+    ZMQContext *s   = h->priv_data;
+    s->context      = zmq_ctx_new();
+    h->is_streamed  = 1;
+
+    av_strstart(uri, "zmq:", &uri);
+
+    /*publish during write*/
+    if (h->flags & AVIO_FLAG_WRITE) {
+        s->socket = zmq_socket(s->context, ZMQ_PUB);
+        if (!s->socket) {
+            av_log(h, AV_LOG_ERROR, "Error occured during zmq_socket(): %s\n", zmq_strerror(errno));
+            zmq_ctx_destroy(s->context);
+            return AVERROR_EXTERNAL;
+        }
+
+        ret = zmq_bind(s->socket, uri);
+        if (ret < 0) {
+            av_log(h, AV_LOG_ERROR, "Error occured during zmq_bind(): %s\n", zmq_strerror(errno));
+            zmq_close(s->socket);
+            zmq_ctx_destroy(s->context);
+            return AVERROR_EXTERNAL;
+        }
+    }
+
+    /*subscribe for read*/
+    if (h->flags & AVIO_FLAG_READ) {
+        s->socket = zmq_socket(s->context, ZMQ_SUB);
+        if (!s->socket) {
+            av_log(h, AV_LOG_ERROR, "Error occured during zmq_socket(): %s\n", zmq_strerror(errno));
+            zmq_ctx_destroy(s->context);
+            return AVERROR_EXTERNAL;
+        }
+
+        zmq_setsockopt(s->socket, ZMQ_SUBSCRIBE, "", 0);
+        ret = zmq_connect(s->socket, uri);
+        if (ret == -1) {
+            av_log(h, AV_LOG_ERROR, "Error occured during zmq_connect(): %s\n", zmq_strerror(errno));
+            zmq_close(s->socket);
+            zmq_ctx_destroy(s->context);
+            return AVERROR_EXTERNAL;
+        }
+    }
+    return 0;
+}
+
+static int ff_zmq_write(URLContext *h, const unsigned char *buf, int size)
+{
+    int ret;
+    ZMQContext *s = h->priv_data;
+
+    ret = zmq_send(s->socket, buf, size, ZMQ_DONTWAIT);
+    if (ret >= 0)
+        return ret; /*number of sent bytes*/
+
+    /*errno = EAGAIN if messages cannot be pushed*/
+    if (ret == -1 && errno == EAGAIN) {
+        return AVERROR(EAGAIN);
+    } else
+        return AVERROR_EXTERNAL;
+}
+
+static int ff_zmq_read(URLContext *h, unsigned char *buf, int size)
+{
+    int ret;
+    ZMQContext *s = h->priv_data;
+    zmq_msg_t msg;
+    int msg_size;
+
+    zmq_pollitem_t items[] = {
+        { s->socket, 0, ZMQ_POLLIN, 0 }
+    };
+
+    //block for for s->timeout milliseconds
+    zmq_poll(items, 1, s->timeout);
+    if (items[0].revents & ZMQ_POLLIN) {
+        ret = zmq_msg_init(&msg);
+        if (ret == -1) {
+            av_log(h, AV_LOG_ERROR, "Error occured during zmq_msg_init(): %s\n", zmq_strerror(errno));
+            return AVERROR_EXTERNAL;
+        }
+        zmq_recvmsg(s->socket, &msg, 0);
+
+        /*truncate msg if it exceeds available space.*/
+        /* TODO: Add Separate thread for ZMQ read. Use AVFifoBufer similar to udp to avoid truncating message*/
+        msg_size = zmq_msg_size(&msg);
+        if (msg_size > size) {
+            msg_size = size;
+            av_log(h, AV_LOG_WARNING, "ZMQ message exceeds available space in the buffer. Message will be truncated\n");
+        }
+        memcpy(buf, zmq_msg_data(&msg), msg_size);
+        zmq_msg_close(&msg);
+        return msg_size;
+    } else
+        return AVERROR(EAGAIN);
+}
+
+static int ff_zmq_close(URLContext *h)
+{
+    ZMQContext *s = h->priv_data;
+    zmq_close(s->socket);
+    zmq_ctx_destroy(s->context);
+    return 0;
+}
+
+static const AVClass zmq_context_class = {
+    .class_name = "zmq",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+const URLProtocol ff_libzmq_protocol = {
+    .name            = "zmq",
+    .url_close       = ff_zmq_close,
+    .url_open        = ff_zmq_open,
+    .url_read        = ff_zmq_read,
+    .url_write       = ff_zmq_write,
+    .priv_data_size  = sizeof(ZMQContext),
+    .priv_data_class = &zmq_context_class,
+    .flags           = URL_PROTOCOL_FLAG_NETWORK,
+};
diff --git a/libavformat/protocols.c b/libavformat/protocols.c
index ad95659795..face5b29b5 100644
--- a/libavformat/protocols.c
+++ b/libavformat/protocols.c
@@ -68,6 +68,7 @@  extern const URLProtocol ff_librtmpte_protocol;
 extern const URLProtocol ff_libsrt_protocol;
 extern const URLProtocol ff_libssh_protocol;
 extern const URLProtocol ff_libsmbclient_protocol;
+extern const URLProtocol ff_libzmq_protocol;
 
 #include "libavformat/protocol_list.c"