How to render a video with raylib and gstreamer

raylib-video.c

#include "raylib.h"
#include <gst/gst.h>
#include <gst/app/gstappsink.h>


GstElement* createPipeline(const char* filename)
{
    GError      *error;
    gchar       *pipelineString = g_strdup_printf ("filesrc location=%s ! tee name=t ! queue ! decodebin ! videoconvert ! appsink name=output caps=video/x-raw,format=RGBA,pixel-aspect-ratio=1/1 t. ! queue ! decodebin ! audioconvert ! audioresample ! autoaudiosink", filename);
    GstElement  *pipeline = gst_parse_launch (pipelineString, &error);

    if (error != NULL) {
        g_print ("Something goes wrong with pipeline initialization: %s\n", error->message);
        g_clear_error (&error);
        exit (-1);
    }

    g_free(pipelineString);
    return pipeline;
}

void restartPipeline(GstElement *pipeline)
{
    gst_element_seek_simple (pipeline, GST_FORMAT_TIME, GST_SEEK_FLAG_SEGMENT | GST_SEEK_FLAG_FLUSH, 0);
    gst_element_set_state (pipeline, GST_STATE_PLAYING);
}

int main(int argc, char** argv)
{
    // Gstreamer Initialization
    gst_init (&argc, &argv);
  
    GstElement  *pipeline = createPipeline("BigBuckBunny.mp4");
    GstElement  *sink = gst_bin_get_by_name(GST_BIN (pipeline), "output");
    GstMapInfo  mapInfo;
    gint64      duration, position;
    int         frameWidth = 0, frameHeight = 0;
    int         renderWidth = 0, renderHeight = 0;
    float       renderScale = -1.0f;
    int         status = 0;

    // Raylib Initialization
    //--------------------------------------------------------------------------------------
    RenderTexture2D renderTexture;
    int screenWidth = 800;
    int screenHeight = 450;

    SetConfigFlags(FLAG_WINDOW_RESIZABLE); 
    InitWindow(screenWidth, screenHeight, "raylib + gstreamer");

    // Start video
    gst_element_set_state(pipeline, GST_STATE_PLAYING);
    restartPipeline(pipeline);

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        // Update duration & position
        gst_element_query_duration(pipeline, GST_FORMAT_TIME, &duration);
        gst_element_query_position(pipeline, GST_FORMAT_TIME, &position);

        // Keyboard events
        //----------------------------------------------------------------------------------
        
        if (IsKeyPressed(KEY_SPACE))
        {
            GstState state;
            gst_element_get_state (pipeline, &state, NULL, 1);

            if (state == GST_STATE_PLAYING) 
            {
                status = 1;
                gst_element_set_state(pipeline, GST_STATE_PAUSED);
            }
            else 
            {
                status = 0;
                gst_element_set_state (pipeline, GST_STATE_PLAYING);
            }   
        }
        else if (IsKeyPressed(KEY_R))
        {
            status = 2;
            restartPipeline(pipeline);
        } 

        if (IsMouseButtonPressed(MOUSE_BUTTON_LEFT))
        {
            Vector2 mouse = GetMousePosition();
            if (mouse.x >= 5 && mouse.x <= screenWidth-5 && mouse.y>=screenHeight-15 && mouse.y<=screenHeight-5)
                gst_element_seek_simple (pipeline, GST_FORMAT_TIME, GST_SEEK_FLAG_SEGMENT | GST_SEEK_FLAG_FLUSH, (gint64)((1.0f*(mouse.x - 5)/(screenWidth-10))*duration));
        }
        //----------------------------------------------------------------------------------


        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

            ClearBackground(RAYWHITE);

            // Read a sample, if available   
            GstSample* sample = gst_app_sink_try_pull_sample(GST_APP_SINK(sink), 1);

            if (IsWindowResized()) renderScale = -1.0f;

            // First time: get frame width & height from video sample
            if (sample != NULL && frameWidth == 0)
            {
                GstCaps *caps = gst_sample_get_caps (sample);
                GstStructure *s = gst_caps_get_structure (caps, 0);

                gst_structure_get_int (s, "width", &frameWidth);
                gst_structure_get_int (s, "height", &frameHeight);
                
                renderTexture = LoadRenderTexture(frameWidth, frameHeight);
            }
            
            // Scale video to fit window if needed
            if (renderScale < 0 && frameWidth > 0)
            {
                screenWidth = GetScreenWidth();
                screenHeight = GetScreenHeight();

                renderWidth = screenWidth;
                renderHeight = (int)(screenWidth * 1.0f*frameHeight/frameWidth);

                if (renderHeight > screenHeight)
                { 
                    renderHeight = screenHeight;
                    renderWidth = (int)(screenHeight * 1.0f*frameWidth/frameHeight);
                }

                renderScale = 1.0f*renderWidth/frameWidth;
            }

            // Render a frame from video, if available.
            if (sample != NULL)   
            {         
                GstBuffer   *buffer = gst_sample_get_buffer(sample);
                GstMapInfo  mapInfo;

                if (gst_buffer_map (buffer, &mapInfo, GST_MAP_READ)) 
                {
                    UpdateTexture(renderTexture.texture, mapInfo.data);
                    gst_buffer_unmap (buffer, &mapInfo);
                }

                gst_sample_unref(sample);
            }

            DrawTextureEx(renderTexture.texture, (Vector2){(screenWidth-renderWidth)/2, (screenHeight-renderHeight)/2 }, 0, 1.0f*renderWidth/frameWidth, WHITE);
        
            // Draw progress
            DrawRectangle(5, screenHeight-15, screenWidth-10, 10, RAYWHITE);
            DrawRectangle(5, screenHeight-15, (int)((screenWidth-10)*(1.0f*position/duration)), 10, BLUE);

            // Draw the texts
            DrawRectangle(4,4,222,82,GRAY);
            DrawRectangle(5,5,220,80,RAYWHITE);
            DrawText("Press SPACE to play/pause video", 15, 15, 10, GRAY);
            DrawText("Press R to restart video", 15, 30, 10, GRAY);

            // Draw status
            switch (status)
            {
                case 0: DrawText("PLAYING", 15, 60, 20, GREEN); break;
                case 1: DrawText("PAUSED", 15, 60, 20, BLUE); break;
                case 2: DrawText("RESTARTED", 15, 60, 20, GREEN); break;
            }
            
        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);
    gst_deinit();
    
    UnloadRenderTexture(renderTexture);

    CloseWindow();            // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}