openGL ES 在android中通过MediaCodec RGB的buffer转换MP4例子

以下是一个基本的示例，演示如何使用OpenGL ES和MediaCodec将RGB图像数据转换为MP4视频：

1. 首先，需要创建一个OpenGL ES上下文并设置它的表面为MediaCodec的输入表面。这可以通过使用EGL库和MediaCodec的createInputSurface()方法来完成。以下是一个示例代码片段：

EGLDisplay eglDisplay = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
int[] version = new int[2];
EGL14.eglInitialize(eglDisplay, version, 0, version, 1);

int[] configAttribs = {
    EGL14.EGL_RENDERABLE_TYPE, EGL14.EGL_OPENGL_ES2_BIT,
    EGL14.EGL_SURFACE_TYPE, EGL14.EGL_PBUFFER_BIT,
    EGL14.EGL_RED_SIZE, 8,
    EGL14.EGL_GREEN_SIZE, 8,
    EGL14.EGL_BLUE_SIZE, 8,
    EGL14.EGL_ALPHA_SIZE, 8,
    EGL14.EGL_NONE
};

EGLConfig[] configs = new EGLConfig[1];
int[] numConfigs = new int[1];
EGL14.eglChooseConfig(eglDisplay, configAttribs, 0, configs, 0, 1, numConfigs, 0);

int[] surfaceAttribs = {
    EGL14.EGL_WIDTH, inputWidth,
    EGL14.EGL_HEIGHT, inputHeight,
    EGL14.EGL_NONE
};

EGLSurface surface = EGL14.eglCreatePbufferSurface(eglDisplay, configs[0], surfaceAttribs, 0);
EGLContext context = EGL14.eglCreateContext(eglDisplay, configs[0], EGL14.EGL_NO_CONTEXT, new int[] {EGL14.EGL_CONTEXT_CLIENT_VERSION, 2, EGL14.EGL_NONE}, 0);
EGL14.eglMakeCurrent(eglDisplay, surface, surface, context);

MediaCodec codec = MediaCodec.createEncoderByType("video/avc");
MediaFormat format = MediaFormat.createVideoFormat("video/avc", inputWidth, inputHeight);
format.setInteger(MediaFormat.KEY_BIT_RATE, bitrate);
format.setInteger(MediaFormat.KEY_FRAME_RATE, frameRate);
format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, iFrameInterval);
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
Surface inputSurface = codec.createInputSurface();

2. 接下来，需要将RGB图像数据传递到OpenGL ES渲染管道中，并使用MediaCodec的输入表面将渲染结果作为视频帧发送到编码器。以下是一个示例代码片段：

// 将RGB数据传递到纹理中
int[] textures = new int[1];
GLES20.glGenTextures(1, textures, 0);
int textureId = textures[0];
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, inputWidth, inputHeight, 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, ByteBuffer.wrap(rgbData));
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);

// 渲染帧
int vertexShader = ShaderUtils.loadShader(GLES20.GL_VERTEX_SHADER, VERTEX_SHADER);
int fragmentShader = ShaderUtils.loadShader(GLES20.GL_FRAGMENT_SHADER, FRAGMENT_SHADER);
int program = ShaderUtils.createProgram(vertexShader, fragmentShader);
int positionHandle = GLES20.glGetAttribLocation(program, "position");
int textureHandle = GLES20.glGetUniformLocation(program, "texture");
int matrixHandle = GLES20.glGetUniformLocation(program, "matrix");

GLES20.glViewport(0, 0, inputWidth, inputHeight);
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

GLES20.glUseProgram(program);

float[] vertices = {
    -1.0f, -1.0f,
    1.0f, -1.0f,
    -1.0f, 1.0f,
    1.0f, 1.0f
};
ByteBuffer vertexBuffer = ByteBuffer.allocateDirect(vertices.length * 4);
vertexBuffer.order(ByteOrder.nativeOrder());
FloatBuffer floatBuffer = vertexBuffer.asFloatBuffer();
floatBuffer.put(vertices);
floatBuffer.position(0);

GLES20.glVertexAttribPointer(positionHandle, 2, GLES20.GL_FLOAT, false, 0, floatBuffer);
GLES20.glEnableVertexAttribArray(positionHandle);

Matrix.setIdentityM(matrix, 0);
Matrix.scaleM(matrix, 0, -1f, 1f, 1f);
Matrix.rotateM(matrix, 0, 270, 0, 0, 1);
GLES20.glUniformMatrix4fv(matrixHandle, 1, false, matrix, 0);

GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
GLES20.glUniform1i(textureHandle, 0);

GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

// 将渲染结果发送到编码器
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
int outputBufferIndex = codec.dequeueOutputBuffer(bufferInfo, TIMEOUT_US);
if (outputBufferIndex >= 0) {
    ByteBuffer outputBuffer = codec.getOutputBuffer(outputBufferIndex);
    outputBuffer.position(bufferInfo.offset);
    outputBuffer.limit(bufferInfo.offset + bufferInfo.size);
    videoTrackIndex = muxer.addTrack(format);
    muxer.writeSampleData(videoTrackIndex, outputBuffer, bufferInfo);
    codec.releaseOutputBuffer(outputBufferIndex, false);
}

3. 最后，需要在完成所有帧的渲染后释放OpenGL ES上下文和MediaCodec资源。以下是一个示例代码片段：

EGL14.eglDestroySurface(eglDisplay, surface);
EGL14.eglDestroyContext(eglDisplay, context);
EGL14.eglTerminate(eglDisplay);

codec.stop();
codec.release();

muxer.stop();
muxer.release();

注意：这只是一个基本示例，你需要根据你的具体情况进行修改。例如，你需要在每一帧之间等待编码器的输出缓冲区，以确保数据正确输出。