[vlc-devel] [PATCH 3/4] libvlc: add sdl_opengl_player sample
Pierre Lamot
pierre at videolabs.io
Tue Jul 3 14:38:36 CEST 2018
this sample shows a simple use of libvlc_video_set_opengl_callbacks
---
doc/libvlc/sdl_opengl_player.cpp | 316 +++++++++++++++++++++++++++++++
1 file changed, 316 insertions(+)
create mode 100644 doc/libvlc/sdl_opengl_player.cpp
diff --git a/doc/libvlc/sdl_opengl_player.cpp b/doc/libvlc/sdl_opengl_player.cpp
new file mode 100644
index 0000000000..290b680629
--- /dev/null
+++ b/doc/libvlc/sdl_opengl_player.cpp
@@ -0,0 +1,316 @@
+//g++ sdl_opengl_player.cpp $(pkg-config --cflags --libs libvlc sdl2 gl)
+
+/* Licence WTFPL */
+/* Written by Pierre Lamot */
+
+#include <exception>
+#include <mutex>
+#include <iostream>
+
+#include <SDL2/SDL.h>
+#define GL_GLEXT_PROTOTYPES 1
+#include <SDL2/SDL_opengl.h>
+#include <vlc/vlc.h>
+
+/*
+ * This program show how to use libvlc_video_set_opengl_callbacks API.
+ *
+ * The main idea is to set up libvlc to render into FBO, and to use a
+ * triple buffer mechanism to share textures between VLC and the rendering
+ * thread of our application
+ */
+
+// Shader sources
+const GLchar* vertexSource =
+ "attribute vec4 a_position; \n"
+ "attribute vec2 a_uv; \n"
+ "varying vec2 v_TexCoordinate; \n"
+ "void main() \n"
+ "{ \n"
+ " v_TexCoordinate = a_uv; \n"
+ " gl_Position = vec4(a_position.xyz, 1.0); \n"
+ "} \n";
+
+const GLchar* fragmentSource =
+ "precision mediump float; \n"
+ "uniform sampler2D u_videotex; \n"
+ "varying vec2 v_TexCoordinate; \n"
+ "void main() \n"
+ "{ \n"
+ " gl_FragColor = texture2D(u_videotex, v_TexCoordinate); \n"
+ "} \n";
+
+class VLCVideo
+{
+public:
+ VLCVideo(SDL_Window *window):
+ m_win(window)
+ {
+ const char *args[] = {
+ "--verbose=4"
+ };
+ m_vlc = libvlc_new(sizeof(args) / sizeof(*args), args);
+
+ //VLC opengl context needs to be shared with SDL context
+ SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+ m_ctx = SDL_GL_CreateContext(window);
+ }
+
+ ~VLCVideo()
+ {
+ stop();
+ if (m_vlc)
+ libvlc_release(m_vlc);
+ }
+
+ bool playMedia(const char* url)
+ {
+ m_media = libvlc_media_new_location (m_vlc, url);
+ if (m_media == NULL) {
+ fprintf(stderr, "unable to create media %s", url);
+ return false;
+ }
+ m_mp = libvlc_media_player_new_from_media (m_media);
+ if (m_mp == NULL) {
+ fprintf(stderr, "unable to create media player");
+ libvlc_media_release(m_media);
+ return false;
+ }
+ // Define the opengl rendering callbacks
+ libvlc_video_set_opengl_callbacks(m_mp, create_fbo, destroy_fbo, make_current, get_proc_address, render_fbo, this);
+
+ // Play the video
+ libvlc_media_player_play (m_mp);
+
+ return true;
+ }
+
+ void stop()
+ {
+ if (m_mp) {
+ libvlc_media_player_release(m_mp);
+ m_mp = nullptr;
+ }
+ if (m_media) {
+ libvlc_media_release(m_media);
+ m_media = nullptr;
+ }
+ }
+
+ /// return the texture to be displayed
+ GLuint getVideoFrame(bool* out_updated)
+ {
+ std::lock_guard<std::mutex> lock(m_text_lock);
+ if (out_updated)
+ *out_updated = m_updated;
+ if (m_updated) {
+ std::swap(m_idx_swap, m_idx_display);
+ m_updated = false;
+ }
+ return m_tex[m_idx_display];
+ }
+
+ /// this callback is called to create the surfaces and FBO used by VLC to perform its rendering
+ static void create_fbo(void* data, size_t width, size_t height)
+ {
+ VLCVideo* that = reinterpret_cast<VLCVideo*>(data);
+ glGenTextures(3, that->m_tex);
+ glGenFramebuffers(3, that->m_fbo);
+
+ for (int i = 0; i < 3; i++) {
+ glBindTexture(GL_TEXTURE_2D, that->m_tex[i]);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+ glBindFramebuffer(GL_FRAMEBUFFER, that->m_fbo[i]);
+ glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, that->m_tex[i], 0);
+ }
+ glBindTexture(GL_TEXTURE_2D, 0);
+
+ GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+
+ if (status != GL_FRAMEBUFFER_COMPLETE) {
+ return;
+ }
+ glBindFramebuffer(GL_FRAMEBUFFER, 0);
+ }
+
+ // This callback is called to release resources created by create_fbo
+ static void destroy_fbo(void* data)
+ {
+ VLCVideo* that = reinterpret_cast<VLCVideo*>(data);
+ glDeleteTextures(3, that->m_tex);
+ glDeleteFramebuffers(3, that->m_fbo);
+ }
+
+ //This callback is called before and after VLC render the videoframe
+ //This will bind the rendering FBO to the current context
+ static void render_fbo(void* data, bool enter)
+ {
+ VLCVideo* that = reinterpret_cast<VLCVideo*>(data);
+ if (enter) {
+ glBindFramebuffer(GL_FRAMEBUFFER, that->m_fbo[that->m_idx_render]);
+ } else {
+ glBindFramebuffer(GL_FRAMEBUFFER, 0);
+ {
+ std::lock_guard<std::mutex> lock(that->m_text_lock);
+ that->m_updated = true;
+ std::swap(that->m_idx_swap, that->m_idx_render);
+ }
+ }
+ }
+
+ // This callback is called to set the OpenGL context
+ static bool make_current(void* data, bool current)
+ {
+ VLCVideo* that = reinterpret_cast<VLCVideo*>(data);
+ if (current)
+ return SDL_GL_MakeCurrent(that->m_win, that->m_ctx) == 0;
+ else
+ return SDL_GL_MakeCurrent(that->m_win, 0) == 0;
+ }
+
+ // This callback is called by VLC to get OpenGL functions.
+ static void* get_proc_address(void* /*data*/, const char* current)
+ {
+ return SDL_GL_GetProcAddress(current);
+ }
+
+private:
+ //VLC objects
+ libvlc_instance_t* m_vlc = nullptr;
+ libvlc_media_player_t* m_mp = nullptr;
+ libvlc_media_t* m_media = nullptr;
+
+ //FBO data
+ std::mutex m_text_lock;
+ GLuint m_tex[3];
+ GLuint m_fbo[3];
+ size_t m_idx_render = 0;
+ size_t m_idx_swap = 1;
+ size_t m_idx_display = 2;
+ bool m_updated = false;
+
+ //SDL context
+ SDL_Window* m_win;
+ SDL_GLContext m_ctx;
+};
+
+int main(int argc, char** argv)
+{
+ if (argc != 2) {
+ fprintf(stderr, "usage: %s <uri>\n", argv[0]);
+ return 1;
+ }
+
+ // SDL_Init(SDL_INIT_VIDEO);
+ SDL_Window* wnd = SDL_CreateWindow("test",
+ SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+ 640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
+
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+ SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+ SDL_GL_SetSwapInterval(0);
+ SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+ SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+
+ SDL_GLContext glc = SDL_GL_CreateContext(wnd);
+
+ VLCVideo video(wnd);
+
+ SDL_Renderer* rdr = SDL_CreateRenderer(
+ wnd, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE);
+
+ // Create Vertex Array Object
+ GLuint vao;
+ glGenVertexArrays(1, &vao);
+ glBindVertexArray(vao);
+
+ // Create a Vertex Buffer Object and copy the vertex data to it
+ GLuint vbo;
+ glGenBuffers(1, &vbo);
+
+ //vertex X, vertex Y, UV X, UV Y
+ GLfloat vertices[] = {
+ -0.5f, 0.5f, 0.f, 1.f,
+ -0.5f, -0.5f, 0.f, 0.f,
+ 0.5f, 0.5f, 1.f, 1.f,
+ 0.5f, -0.5f, 1.f, 0.f
+ };
+
+ glBindBuffer(GL_ARRAY_BUFFER, vbo);
+ glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+ // Create and compile the vertex shader
+ GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+ glShaderSource(vertexShader, 1, &vertexSource, NULL);
+ glCompileShader(vertexShader);
+
+ // Create and compile the fragment shader
+ GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+ glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
+ glCompileShader(fragmentShader);
+
+ // Link the vertex and fragment shader into a shader program
+ GLuint shaderProgram = glCreateProgram();
+ glAttachShader(shaderProgram, vertexShader);
+ glAttachShader(shaderProgram, fragmentShader);
+ glLinkProgram(shaderProgram);
+ glUseProgram(shaderProgram);
+
+ // Specify the layout of the vertex data
+ GLint posAttrib = glGetAttribLocation(shaderProgram, "a_position");
+ glEnableVertexAttribArray(posAttrib);
+ glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 4*sizeof(float), 0);
+
+ // Specify the layout of the vertex data
+ GLint uvAttrib = glGetAttribLocation(shaderProgram, "a_uv");
+ glEnableVertexAttribArray(uvAttrib);
+ glVertexAttribPointer(uvAttrib, 2, GL_FLOAT, GL_FALSE, 4*sizeof(float), (GLvoid*)(2*sizeof(float)));
+
+ // Specify the texture of the video
+ GLint textUniform = glGetUniformLocation(shaderProgram, "u_videotex");
+ glActiveTexture(GL_TEXTURE0);
+ glUniform1i(textUniform, /*GL_TEXTURE*/0);
+
+ //start playing the video
+ if (!video.playMedia(argv[1])) {
+ SDL_DestroyWindow(wnd);
+ SDL_Quit();
+ return 1;
+ }
+
+ bool updated = false;
+ bool quit = false;
+ while(!quit) {
+ SDL_Event e;
+ while(SDL_PollEvent(&e)) {
+ if(e.type == SDL_QUIT)
+ quit = true;
+ }
+
+ // Clear the screen to black
+ glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+ glClear(GL_COLOR_BUFFER_BIT);
+
+ // Get the current video texture and bind it
+ GLuint tex = video.getVideoFrame(&updated);
+ glBindTexture(GL_TEXTURE_2D, tex);
+
+ // Draw the video rectangle
+ glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+ glBindTexture(GL_TEXTURE_2D, 0);
+
+ SDL_GL_SwapWindow(wnd);
+ };
+
+ video.stop();
+
+ SDL_DestroyWindow(wnd);
+ SDL_Quit();
+
+ return 0;
+}
--
2.17.1
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