Introduction
Hello! I needed to call some GStreamer C++ code in my application from node, however there isn't a lot of information on how to do this so I thought I'd try it myself. Just leaving this to remind myself later of the basics and if it helps anyone else, Win-Win. :)
Also I am pretty new to creating native modules, so this was a good learning experience.
This sample basically takes the sample GStreamer application Basic Tutorial 1: Hello World source and enables it to be called via NodeJS.
Here I will be using the "node-addon-api"package for wrapping.
Requirements
- Gstreamer + GStreamer-Devel installed
- PkgConfig
- NodeJS
First we need to create the C++ file, open up "src/gstreamer.cc" and type/copy the following:
#include <gst/gst.h>
#include <napi.h>
using namespace Napi;
Number Play (const CallbackInfo& info)
{
GstElement *pipeline;
GstBus *bus;
GstMessage *message;
gst_init(NULL, NULL);
pipeline = gst_parse_launch(
"playbin uri=https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm"
, NULL);
gst_element_set_state(pipeline, GST_STATE_PLAYING);
bus = gst_element_get_bus(pipeline);
message = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, (GstMessageType)(GST_MESSAGE_ERROR | GST_MESSAGE_EOS));
if (GST_MESSAGE_TYPE(message) == GST_MESSAGE_ERROR)
{
g_error("An error occured");
}
gst_message_unref(message);
gst_object_unref(bus);
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(pipeline);
return Number::New(info.Env(), 0);
}
Object Init (Env env, Object exports)
{
exports.Set("play", Function::New(env, Play));
return exports;
}
NODE_API_MODULE(addon, Init);
Next we need to create the "bindings.gyp" file which allows us to compile native addon modules for NodeJS.
Open it up and add the following:
{
"targets": [
{
"target_name": "gstreamer",
"sources": [
"src/gstreamer.cc"
],
"include_dirs": [
"<!@(node -p \"require('node-addon-api').include\")",
"<!@(pkg-config gstreamer-1.0 --cflags-only-I | sed s/-I//g)"
],
"libraries": [
"<!@(pkg-config gstreamer-1.0 --libs)"
],
"cflags!": ["-fno-exceptions"],
"cflags_cc!": ["-fno-exceptions"],
"defines": ["NAPI_CPP_EXCEPTIONS"]
}
]
}
Here we basically include the needed libraries and header files, in this case we only need GStreamer.
Next we need to initialize the NodeJS Module.
npm init -y
Install the necessary packages:
npm i bindings node-addon-api
Now we need to build the native addon:
npm i
Now that the native module has been built we can create a test file to test it, open up "test.js" and add the following:
const addon = require('bindings')('gstreamer');
addon.play();
Done now we just need to execute it:
node test.js
If done correctly you should now see the video playing in a new window.
Next I would like to pass the src to the native module and play that. Possibly an RTSP feed. :)
Github Repo:
https://github.com/ethand91/gstreamer-node-samples/tree/master/hello-world
Like me work? Any support is appreciated. :)
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