Bump version: 5.3 → 5.4

Better CORS support

.bumpversion.cfg

@@ -1,7 +1,7 @@
 [bumpversion]
 commit = True
 tag = True
-current_version = 5.0
+current_version = 5.4
 parse = (?P<major>\d+)\.(?P<minor>\d+)
 serialize = 
 	{major}.{minor}

.github/FUNDING.yml

@@ -1,4 +1,4 @@
 # These are supported funding model platforms
 
 patreon: pikvm
-custom: https://www.paypal.me/mdevaev
+#custom: https://www.paypal.me/mdevaev

README.md

@@ -40,6 +40,7 @@ You'll need  ```make```, ```gcc```, ```libevent``` with ```pthreads``` support,
 * Arch: `sudo pacman -S libevent libjpeg-turbo libutil-linux libbsd`.
 * Raspbian: `sudo apt install libevent-dev libjpeg8-dev libbsd-dev`. Add `libgpiod-dev` for `WITH_GPIO=1` and `libsystemd-dev` for `WITH_SYSTEMD=1`.
 * Debian/Ubuntu: `sudo apt install build-essential libevent-dev libjpeg-dev libbsd-dev`.
+* Alpine: `sudo apk add libevent-dev libbsd-dev libjpeg-turbo-dev musl-dev`. Build with `WITH_PTHREAD_NP=0`.
 
 To enable GPIO support install [libgpiod](https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/about) and pass option ```WITH_GPIO=1```. If the compiler reports about a missing function ```pthread_get_name_np()``` (or similar), add option ```WITH_PTHREAD_NP=0``` (it's enabled by default). For the similar error with ```setproctitle()``` add option ```WITH_SETPROCTITLE=0```.
 
@@ -56,6 +57,8 @@ FreeBSD port: https://www.freshports.org/multimedia/ustreamer.
 
 -----
 # Usage
+**For M2M hardware encoding on Raspberry Pi, you need at least 5.15.32 kernel. OpenMAX and MMAL support on older kernels is deprecated and removed.**
+
 Without arguments, ```ustreamer``` will try to open ```/dev/video0``` with 640x480 resolution and start streaming on  ```http://127.0.0.1:8080```. You can override this behavior using parameters ```--device```, ```--host``` and ```--port```. For example, to stream to the world, run:
 ```
 # ./ustreamer --device=/dev/video1 --host=0.0.0.0 --port=80
@@ -97,6 +100,9 @@ $ modprobe bcm2835-v4l2 max_video_width=2592 max_video_height=1944
 -----
 # Integrations
 
+## Janus
+µStreamer supports bandwidth-efficient streaming using [H.264 compression](https://en.wikipedia.org/wiki/Advanced_Video_Coding) and the Janus WebRTC server. See the [Janus integration guide](docs/h264.md) for full details.
+
 ## Nginx
 When uStreamer is behind an Nginx proxy, it's buffering behavior introduces latency into the video stream. It's possible to disable Nginx's buffering to eliminate the additional latency:
 

README.ru.md

@@ -56,6 +56,8 @@ $ ./ustreamer --help
 
 -----
 # Использование
+**Для аппаратного кодирования M2M на Raspberry Pi, вам нужно ядро минимальной версии 5.15.32. Поддержка OpenMAX и MMAL для более старых ядер объявлена устаревшей и была удалена.**
+
 Будучи запущенным без аргументов, ```ustreamer``` попробует открыть устройство ```/dev/video0``` с разрешением 640x480 и начать трансляцию на ```http://127.0.0.1:8080```. Это поведение может быть изменено с помощью опций ```--device```, ```--host``` и ```--port```. Пример вещания на всю сеть по 80-м порту:
 ```
 # ./ustreamer --device=/dev/video1 --host=0.0.0.0 --port=80

docs/h264.md

@@ -0,0 +1,231 @@
+# Streaming H.264 Video over WebRTC with Janus
+
+µStreamer supports bandwidth-efficient streaming using [H.264 compression](https://en.wikipedia.org/wiki/Advanced_Video_Coding) and the Janus WebRTC server.
+
+This guide explains how to configure µStreamer to provide an H.264 video stream and consume it within a web application using WebRTC.
+
+## Components
+
+In addition to µStreamer, H.264 streaming involves the following components:
+
+- [**Janus**](https://janus.conf.meetecho.com/): A general-purpose WebRTC server.
+- [**µStreamer Janus Plugin**](https://github.com/pikvm/ustreamer/tree/master/janus): A Janus plugin that allows Janus to consume a video stream from µStreamer via shared memory.
+- [**Janus JavaScript Client**](https://janus.conf.meetecho.com/docs/JS.html): A frontend library that communicates with the Janus server and the µStreamer Janus plugin.
+
+## Control Flow
+
+To connect to a µStreamer video stream over WebRTC, an application must establish the following control flow:
+
+1. The backend server starts the µStreamer service.
+1. The backend server starts the Janus WebRTC server with the µStreamer Janus plugin.
+1. The client-side JavaScript application establishes a connection to the Janus server.
+1. The client-side JavaScript application instructs the Janus server to attach the µStreamer Janus plugin and start the video stream.
+1. The client-side JavaScript application renders the video stream in the web browser.
+
+## Server Setup
+
+### Prerequisites
+
+To integrate with Janus, µStreamer has the following prerequisites:
+
+- The system packages that µStreamer depends on (see the [main build instructions](../README.md#building)).
+- The Janus WebRTC server with WebSockets transport enabled (see the [Janus documentation](https://github.com/meetecho/janus-gateway)).
+
+### Fixing Janus C Headers
+
+To compile µStreamer with the Janus option, (see [“Installation”](#installation)), you need to make the Janus header files available within µStreamer's build context.
+
+First, create a symbolic link from `/usr/include` to the Janus install directory. By default, Janus installs to `/opt/janus`.
+
+```sh
+ln -s /opt/janus/include/janus /usr/include/janus
+```
+
+Janus uses `#include` paths that make it difficult for third-party libraries to build against its headers. To fix this, modify the `#include` directive in `janus/plugins/plugin.h` to prepend a `../` to the included file name (`#include "refcount.h"` → `#include "../refcount.h"`).
+
+```sh
+sed \
+  --in-place \
+  --expression 's|^#include "refcount.h"$|#include "../refcount.h"|g' \
+  /usr/include/janus/plugins/plugin.h
+```
+
+### Installation
+
+First, compile µStreamer with the Janus plugin option (`WITH_JANUS`).
+
+```sh
+git clone --depth=1 https://github.com/pikvm/ustreamer
+cd ustreamer
+make WITH_JANUS=1
+```
+
+The `WITH_JANUS` option compiles the µStreamer Janus plugin and outputs it to `janus/libjanus_ustreamer.so`. Move this file to the plugin directory of your Janus installation.
+
+```sh
+mv \
+  janus/libjanus_ustreamer.so \
+  /opt/janus/lib/janus/plugins/libjanus_ustreamer.so
+```
+
+Finally, specify a qualifier for the shared memory object so that the µStreamer Janus plugin can read  µStreamer's video data.
+
+```sh
+cat > /opt/janus/lib/janus/configs/janus.plugin.ustreamer.jcfg <<EOF
+memsink: {
+  object = "demo::ustreamer::h264"
+}
+EOF
+```
+
+### Start µStreamer and the Janus WebRTC Server
+
+For µStreamer to share the video stream with the µStreamer Janus plugin, µStreamer must run with the following command-line flags:
+
+- `--h264-sink` with the qualifier of the shared memory object you specified above (`demo::ustreamer::h264`)
+- `--h264-sink-mode` with the permissions bitmask for the shared memory object (e.g., `660`)
+- `--h264-sink-rm` to clean up the shared memory object when the µStreamer process exits
+
+To load the µStreamer Janus plugin and configuration, the Janus WebRTC server must run with the following command-line flags:
+
+- `--configs-folder` with the path to the Janus configuration directory (e.g., `/opt/janus/lib/janus/configs/`)
+- `--plugins-folder` with the path to the Janus plugin directory (e.g., `/opt/janus/lib/janus/plugins/`)
+
+## Client Setup
+
+Once an application's backend server is running µStreamer and Janus, a browser-based JavaScript application can consume the server's video stream.
+
+### Prerequisites
+
+The client needs to load the following JavaScript libraries:
+
+- [WebRTC Adapter library](https://webrtc.github.io/adapter/adapter-8.1.0.js) (`webrtc-adapter.js`, version `8.1.0`)
+- [Janus Gateway JavaScript library](https://raw.githubusercontent.com/meetecho/janus-gateway/v1.0.0/html/janus.js) (`janus.js`, version `1.0.0`)
+
+### Control Flow
+
+The client-side JavaScript application uses the following control flow:
+
+1. The client loads and initializes the Janus client library.
+1. The client establishes a WebSockets connection to the Janus server.
+1. The client instructs the Janus server to attach the µStreamer Janus plugin.
+1. On success, the client obtains a plugin handle through which it can send requests directly to the µStreamer Janus plugin. The client processes responses via the `attach` callbacks:
+   - `onmessage` for general messages
+   - `onremotetrack` for the H.264 video stream
+1. The client issues a `watch` request to the µStreamer Janus plugin, which initiates the H.264 stream in the plugin itself.
+   - It takes a few seconds for uStreamer's video stream to become available to Janus. The first `watch` request may fail, so the client must retry the `watch` request.
+1. The client and server negotiate the underlying parameters of the WebRTC session. This procedure is called JavaScript Session Establishment Protocol (JSEP). The server makes a `jsepOffer` to the client, and the client responds with a `jsepAnswer`.
+1. The client issues a `start` request to the µStreamer Janus plugin to indicate that the client wants to begin consuming the video stream.
+1. The µStreamer Janus plugin delivers the H.264 video stream to the client via WebRTC.
+1. The Janus client library invokes the `onremotetrack` callback. The client attaches the video stream to the `<video>` element, rendering the video stream in the browser window.
+
+### Sample Code
+
+```html
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>µStreamer H.264 demo</title>
+  <script src="https://webrtc.github.io/adapter/adapter-8.1.0.js"></script>
+  <!-- janus.js is the JavaScript client library of Janus, as specified above in
+       the prerequisites section of the client setup. You might need to change
+       the `src` path, depending on where you serve this file from. -->
+  <script src="janus.js"></script>
+  <style>
+    video {
+      height: 100%;
+      width: 100%;
+      object-fit: contain;
+    }
+  </style>
+</head>
+<body>
+  <video id="webrtc-output" autoplay playsinline muted></video>
+  <script type="text/javascript">
+    // Initialize Janus library.
+    Janus.init({
+      // Turn on debug logs in the browser console.
+      debug: true,
+
+      // Configure Janus to use standard browser APIs internally.
+      dependencies: Janus.useDefaultDependencies(),
+    });
+
+    // Establish a WebSockets connection to the server.
+    const janus = new Janus({
+      // Specify the URL of the Janus server’s WebSockets endpoint.
+      server: `ws://${window.location.hostname}:8188/`,
+
+      // Callback function if the client connects successfully.
+      success: attachUStreamerPlugin,
+
+      // Callback function if the client fails to connect.
+      error: console.error,
+    });
+
+    let uStreamerPluginHandle = null;
+
+    function attachUStreamerPlugin() {
+      // Instruct the server to attach the µStreamer Janus plugin.
+      janus.attach({
+        // Qualifier of the plugin.
+        plugin: "janus.plugin.ustreamer",
+
+        // Callback function, for when the server attached the plugin
+        // successfully.
+        success: function (pluginHandle) {
+          uStreamerPluginHandle = pluginHandle;
+          // Instruct the µStreamer Janus plugin to initiate the video stream.
+          uStreamerPluginHandle.send({ message: { request: "watch" } });
+        },
+
+        // Callback function if the server fails to attach the plugin.
+        error: console.error,
+
+        // Callback function for processing messages from the Janus server.
+        onmessage: function (msg, jsepOffer) {
+          // 503 indicates that the plugin is not ready to stream yet. Retry the
+          // watch request until the video stream is available.
+          if (msg.error_code === 503) {
+            uStreamerPluginHandle.send({ message: { request: "watch" } });
+            return;
+          }
+
+          // If there is a JSEP offer, respond to it. This starts the WebRTC
+          // connection.
+          if (jsepOffer) {
+            uStreamerPluginHandle.createAnswer({
+              jsep: jsepOffer,
+              // Prevent the client from sending audio and video, as this would
+              // trigger a permission dialog in the browser.
+              media: { audioSend: false, videoSend: false },
+              success: function (jsepAnswer) {
+                uStreamerPluginHandle.send({
+                  message: { request: "start" },
+                  jsep: jsepAnswer,
+                });
+              },
+              error: console.error,
+            });
+          }
+        },
+
+        // Callback function, for when the video stream arrives.
+        onremotetrack: function (mediaStreamTrack, mediaId, isAdded) {
+          if (isAdded) {
+            // Attach the received media track to the video element. Cloning the
+            // mediaStreamTrack creates a new object with a distinct, globally
+            // unique stream identifier.
+            const videoElement = document.getElementById("webrtc-output");
+            const stream = new MediaStream();
+            stream.addTrack(mediaStreamTrack.clone());
+            videoElement.srcObject = stream;
+          }
+        },
+      });
+    }
+  </script>
+</body>
+</html>
+```

man/ustreamer-dump.1

@@ -1,6 +1,6 @@
 .\" Manpage for ustreamer-dump.
 .\" Open an issue or pull request to https://github.com/pikvm/ustreamer to correct errors or typos
-.TH USTREAMER-DUMP 1 "version 5.0" "January 2021"
+.TH USTREAMER-DUMP 1 "version 5.4" "January 2021"
 
 .SH NAME
 ustreamer-dump \- Dump uStreamer's memory sink to file

man/ustreamer.1

@@ -1,6 +1,6 @@
 .\" Manpage for ustreamer.
 .\" Open an issue or pull request to https://github.com/pikvm/ustreamer to correct errors or typos
-.TH USTREAMER 1 "version 5.0" "November 2020"
+.TH USTREAMER 1 "version 5.4" "November 2020"
 
 .SH NAME
 ustreamer \- stream MJPEG video from any V4L2 device to the network

pkg/arch/PKGBUILD

@@ -3,19 +3,19 @@
 
 
 pkgname=ustreamer
-pkgver=5.0
+pkgver=5.4
 pkgrel=1
 pkgdesc="Lightweight and fast MJPEG-HTTP streamer"
 url="https://github.com/pikvm/ustreamer"
 license=(GPL)
 arch=(i686 x86_64 armv6h armv7h aarch64)
-depends=(libjpeg libevent libbsd libgpiod)
-makedepends=(gcc make)
+depends=(libjpeg libevent libbsd libgpiod systemd)
+makedepends=(gcc make systemd)
 source=(${pkgname}::"git+https://github.com/pikvm/ustreamer#commit=v${pkgver}")
 md5sums=(SKIP)
 
 
-_options="WITH_GPIO=1"
+_options="WITH_GPIO=1 WITH_SYSTEMD=1"
 if [ -e /usr/bin/python3 ]; then
 	_options="$_options WITH_PYTHON=1"
 	depends+=(python)
@@ -26,11 +26,6 @@ if [ -e /usr/include/janus/plugins/plugin.h ];then
 	makedepends+=(janus-gateway-pikvm)
 	_options="$_options WITH_JANUS=1"
 fi
-if [ -e /usr/include/systemd/sd-daemon.h ];then
-	depends+=(systemd)
-	makedepends+=(systemd)
-	_options="$_options WITH_SYSTEMD=1"
-fi
 
 
 # LD does not link mmal with this option

pkg/openwrt/Makefile

@@ -6,7 +6,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=ustreamer
-PKG_VERSION:=5.0
+PKG_VERSION:=5.4
 PKG_RELEASE:=1
 PKG_MAINTAINER:=Maxim Devaev <mdevaev@gmail.com>
 

python/setup.py

@@ -8,7 +8,7 @@ from setuptools import setup
 if __name__ == "__main__":
     setup(
         name="ustreamer",
-        version="5.0",
+        version="5.4",
         description="uStreamer tools",
         author="Maxim Devaev",
         author_email="mdevaev@gmail.com",

src/libs/config.h

@@ -23,7 +23,7 @@
 #pragma once
 
 #define VERSION_MAJOR 5
-#define VERSION_MINOR 0
+#define VERSION_MINOR 4
 
 #define MAKE_VERSION2(_major, _minor) #_major "." #_minor
 #define MAKE_VERSION1(_major, _minor) MAKE_VERSION2(_major, _minor)

src/libs/tools.h

@@ -28,6 +28,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
+#include <limits.h>
 #include <locale.h>
 #include <errno.h>
 #include <math.h>
@@ -37,6 +38,15 @@
 #include <sys/file.h>
 
 
+#ifdef NDEBUG
+#	error WTF dude? Asserts are good things!
+#endif
+
+#if CHAR_BIT != 8
+#	error There are not 8 bits in a char!
+#endif
+
+
 #define RN "\r\n"
 
 #define INLINE inline __attribute__((always_inline))

src/ustreamer/http/server.c

@@ -76,7 +76,7 @@ server_s *server_init(stream_s *stream) {
 	assert(!evthread_use_pthreads());
 	assert((run->base = event_base_new()));
 	assert((run->http = evhttp_new(run->base)));
-	evhttp_set_allowed_methods(run->http, EVHTTP_REQ_GET|EVHTTP_REQ_HEAD);
+	evhttp_set_allowed_methods(run->http, EVHTTP_REQ_GET|EVHTTP_REQ_HEAD|EVHTTP_REQ_OPTIONS);
 	return server;
 }
 
@@ -212,14 +212,36 @@ void server_loop_break(server_s *server) {
 	event_base_loopbreak(RUN(base));
 }
 
+#define GET_HEADER(_key) \
+	evhttp_find_header(evhttp_request_get_input_headers(request), _key)
+
 #define ADD_HEADER(_key, _value) \
 	assert(!evhttp_add_header(evhttp_request_get_output_headers(request), _key, _value))
 
 static int _http_preprocess_request(struct evhttp_request *request, server_s *server) {
 	RUN(last_request_ts) = get_now_monotonic();
 
+	if (server->allow_origin[0] != '\0') {
+		const char *cors_headers = GET_HEADER("Access-Control-Request-Headers");
+		const char *cors_method = GET_HEADER("Access-Control-Request-Method");
+
+		ADD_HEADER("Access-Control-Allow-Origin", server->allow_origin);
+		ADD_HEADER("Access-Control-Allow-Credentials", "true");
+		if (cors_headers != NULL) {
+			ADD_HEADER("Access-Control-Allow-Headers", cors_headers);
+		}
+		if (cors_method != NULL) {
+			ADD_HEADER("Access-Control-Allow-Methods", cors_method);
+		}
+	}
+
+	if (evhttp_request_get_command(request) == EVHTTP_REQ_OPTIONS) {
+		evhttp_send_reply(request, HTTP_OK, "OK", NULL);
+		return -1;
+	}
+
 	if (RUN(auth_token)) {
-		const char *token = evhttp_find_header(evhttp_request_get_input_headers(request), "Authorization");
+		const char *token = GET_HEADER("Authorization");
 
 		if (token == NULL || strcmp(token, RUN(auth_token)) != 0) {
 			ADD_HEADER("WWW-Authenticate", "Basic realm=\"Restricted area\"");
@@ -228,8 +250,8 @@ static int _http_preprocess_request(struct evhttp_request *request, server_s *se
 		}
 	}
 
-	if (evhttp_request_get_command(request) == EVHTTP_REQ_HEAD) { \
-		evhttp_send_reply(request, HTTP_OK, "OK", NULL); \
+	if (evhttp_request_get_command(request) == EVHTTP_REQ_HEAD) {
+		evhttp_send_reply(request, HTTP_OK, "OK", NULL);
 		return -1;
 	}
 
@@ -464,9 +486,6 @@ static void _http_callback_snapshot(struct evhttp_request *request, void *v_serv
 	assert((buf = evbuffer_new()));
 	assert(!evbuffer_add(buf, (const void *)EX(frame->data), EX(frame->used)));
 
-	if (server->allow_origin[0] != '\0') {
-		ADD_HEADER("Access-Control-Allow-Origin", server->allow_origin);
-	}
 	ADD_HEADER("Cache-Control", "no-store, no-cache, must-revalidate, proxy-revalidate, pre-check=0, post-check=0, max-age=0");
 	ADD_HEADER("Pragma", "no-cache");
 	ADD_HEADER("Expires", "Mon, 3 Jan 2000 12:34:56 GMT");
@@ -580,6 +599,7 @@ static void _http_callback_stream_write(struct bufferevent *buf_event, void *v_c
 #	define BOUNDARY "boundarydonotcross"
 
 	stream_client_s *client = (stream_client_s *)v_client;
+	struct evhttp_request *request = client->request; // for GET_HEADER
 	server_s *server = client->server;
 
 	long double now = get_now_monotonic();
@@ -620,9 +640,24 @@ static void _http_callback_stream_write(struct bufferevent *buf_event, void *v_c
 
 	if (client->need_initial) {
 		assert(evbuffer_add_printf(buf, "HTTP/1.0 200 OK" RN));
+		
 		if (client->server->allow_origin[0] != '\0') {
-			assert(evbuffer_add_printf(buf, "Access-Control-Allow-Origin: %s" RN, client->server->allow_origin));
+			const char *cors_headers = GET_HEADER("Access-Control-Request-Headers");
+			const char *cors_method = GET_HEADER("Access-Control-Request-Method");
+
+			assert(evbuffer_add_printf(buf,
+				"Access-Control-Allow-Origin: %s" RN
+				"Access-Control-Allow-Credentials: true" RN,
+				client->server->allow_origin				
+			));
+			if (cors_headers != NULL) {
+				assert(evbuffer_add_printf(buf, "Access-Control-Allow-Headers: %s" RN, cors_headers));
+			}
+			if (cors_method != NULL) {
+				assert(evbuffer_add_printf(buf, "Access-Control-Allow-Methods: %s" RN, cors_method));
+			}
 		}
+
 		assert(evbuffer_add_printf(buf,
 			"Cache-Control: no-store, no-cache, must-revalidate, proxy-revalidate, pre-check=0, post-check=0, max-age=0" RN
 			"Pragma: no-cache" RN
@@ -895,7 +930,7 @@ static char *_http_get_client_hostport(struct evhttp_request *request) {
 		assert(addr = strdup(peer));
 	}
 
-	const char *xff = evhttp_find_header(evhttp_request_get_input_headers(request), "X-Forwarded-For");
+	const char *xff = GET_HEADER("X-Forwarded-For");
 	if (xff) {
 		if (addr) {
 			free(addr);
@@ -918,3 +953,5 @@ static char *_http_get_client_hostport(struct evhttp_request *request) {
 	free(addr);
 	return hostport;
 }
+
+#undef GET_HEADER

src/ustreamer/m2m.c

@@ -70,7 +70,7 @@ m2m_encoder_s *m2m_h264_encoder_init(const char *name, const char *path, unsigne
 
 m2m_encoder_s *m2m_mjpeg_encoder_init(const char *name, const char *path, unsigned quality) {
 	const double b_min = 25;
-	const double b_max = 25000;
+	const double b_max = 20000;
 	const double step = 25;
 	double bitrate = log10(quality) * (b_max - b_min) / 2 + b_min;
 	bitrate = step * round(bitrate / step);

src/ustreamer/main.c

@@ -20,16 +20,6 @@
 *****************************************************************************/
 
 
-#include <assert.h>
-#ifdef NDEBUG
-#	error WTF dude? Asserts are good things!
-#endif
-
-#include <limits.h>
-#if CHAR_BIT != 8
-#	error There are not 8 bits in a char!
-#endif
-
 #include <stdio.h>
 #include <stdbool.h>
 #include <signal.h>

src/ustreamer/options.c

@@ -439,7 +439,7 @@ int options_parse(options_s *options, device_s *dev, encoder_s *enc, stream_s *s
 			ADD_SINK("", sink, SINK)
 			ADD_SINK("raw-", raw_sink, RAW_SINK)
 			ADD_SINK("h264-", h264_sink, H264_SINK)
-			case _O_H264_BITRATE:		OPT_NUMBER("--h264-bitrate", stream->h264_bitrate, 25, 25000, 0);
+			case _O_H264_BITRATE:		OPT_NUMBER("--h264-bitrate", stream->h264_bitrate, 25, 20000, 0);
 			case _O_H264_GOP:			OPT_NUMBER("--h264-gop", stream->h264_gop, 0, 60, 0);
 			case _O_H264_M2M_DEVICE:	OPT_SET(stream->h264_m2m_path, optarg);
 #			undef ADD_SINK