在YUV420p上有很多绿色 - > iOS上的OpenGL 2.0着色器中的RGB [英] a lot of GREEN Color at YUV420p --> RGB in OpenGL 2.0 Shader on iOS
问题描述
我想使用ffmpeg和OpenGL ES 2.0
为iOS制作电影播放器,但我有一些问题。输出RGB图像有很多绿色。
这是代码和图片
I want to make a movie player for iOS using ffmpeg and OpenGL ES 2.0 but I have some problem. Output RGB image has a lot of GREEN color. This is code and images
- 480x320 width&高度:
- 512x512纹理宽度&高度
我从ffmpeg AVFrame获得了一个YUV420p行数据。
I got a YUV420p row data from ffmpeg AVFrame.
for (int i = 0, nDataLen = 0; i < 3; i++) {
int nShift = (i == 0) ? 0 : 1;
uint8_t *pYUVData = (uint8_t *)_frame->data[i];
for (int j = 0; j < (mHeight >> nShift); j++) {
memcpy(&pData->pOutBuffer[nDataLen], pYUVData, (mWidth >> nShift));
pYUVData += _frame->linesize[i];
nDataLen += (mWidth >> nShift);
}
}
并准备Y,U&的纹理V频道。
and prepare texture for Y, U & V channel.
//: U Texture
if (sampler1Texture) glDeleteTextures(1, &sampler1Texture);
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &sampler1Texture);
glBindTexture(GL_TEXTURE_2D, sampler1Texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// This is necessary for non-power-of-two textures
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glEnable(GL_TEXTURE_2D);
glTexImage2D(GL_TEXTURE_2D,
0,
GL_LUMINANCE,
texW / 2,
texH / 2,
0,
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
NULL);
//: V Texture
if (sampler2Texture) glDeleteTextures(1, &sampler2Texture);
glActiveTexture(GL_TEXTURE2);
glGenTextures(1, &sampler2Texture);
glBindTexture(GL_TEXTURE_2D, sampler2Texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// This is necessary for non-power-of-two textures
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glEnable(GL_TEXTURE_2D);
glTexImage2D(GL_TEXTURE_2D,
0,
GL_LUMINANCE,
texW / 2,
texH / 2,
0,
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
NULL);
//: Y Texture
if (sampler0Texture) glDeleteTextures(1, &sampler0Texture);
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &sampler0Texture);
glBindTexture(GL_TEXTURE_2D, sampler0Texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// This is necessary for non-power-of-two textures
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glEnable(GL_TEXTURE_2D);
glTexImage2D(GL_TEXTURE_2D,
0,
GL_LUMINANCE,
texW,
texH,
0,
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
NULL);
渲染部分如下。
int _idxU = mFrameW * mFrameH;
int _idxV = _idxU + (_idxU / 4);
// U data
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, sampler1Texture);
glUniform1i(sampler1Uniform, 1);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW / 2, // source width
mFrameH / 2, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
&_frameData[_idxU]);
// V data
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, sampler2Texture);
glUniform1i(sampler2Texture, 2);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW / 2, // source width
mFrameH / 2, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
&_frameData[_idxV]);
// Y data
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, sampler0Texture);
glUniform1i(sampler0Uniform, 0);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW, // source width
mFrameH, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
_frameData);
Vertex Shader&片段着色器在下面。
Vertex Shader & Fragment Shader is below.
attribute vec4 Position;
attribute vec2 TexCoordIn;
varying vec2 TexCoordOut;
varying vec2 TexCoordOut_UV;
uniform mat4 Projection;
uniform mat4 Modelview;
void main()
{
gl_Position = Projection * Modelview * Position;
TexCoordOut = TexCoordIn;
}
uniform sampler2D sampler0; // Y Texture Sampler
uniform sampler2D sampler1; // U Texture Sampler
uniform sampler2D sampler2; // V Texture Sampler
varying highp vec2 TexCoordOut;
void main()
{
highp float y = texture2D(sampler0, TexCoordOut).r;
highp float u = texture2D(sampler2, TexCoordOut).r - 0.5;
highp float v = texture2D(sampler1, TexCoordOut).r - 0.5;
//y = 0.0;
//u = 0.0;
//v = 0.0;
highp float r = y + 1.13983 * v;
highp float g = y - 0.39465 * u - 0.58060 * v;
highp float b = y + 2.03211 * u;
gl_FragColor = vec4(r, g, b, 1.0);
}
Y纹理(灰度)是正确的但U& V有很多绿色。
所以最终的RGB图像(Y + U + V)有很多绿色。
有什么问题?
Y Texture (Grayscale) is correct but U & V has a lot of Green Color. So final RGB image (Y+U+V) has a lot of GREEN Color. What's the problem?
请帮忙。
谢谢。
Please help. thanks.
推荐答案
更改 u
和 v
制服(反之亦然),你会得到正确的结果。
Change u
and v
uniforms (vice versa) and you will have correct result.
所以像素着色器(保持不变):
So pixel shader (stays the same):
uniform sampler2D sampler0; // Y Texture Sampler
uniform sampler2D sampler1; // U Texture Sampler
uniform sampler2D sampler2; // V Texture Sampler
varying highp vec2 TexCoordOut;
void main()
{
highp float y = texture2D(sampler0, TexCoordOut).r;
highp float u = texture2D(sampler2, TexCoordOut).r - 0.5;
highp float v = texture2D(sampler1, TexCoordOut).r - 0.5;
highp float r = y + 1.13983 * v;
highp float g = y - 0.39465 * u - 0.58060 * v;
highp float b = y + 2.03211 * u;
gl_FragColor = vec4(r, g, b, 1.0);
}
和渲染代码:
// RENDERING
int _idxU = mFrameW * mFrameH;
int _idxV = _idxU + (_idxU / 4);
// U data
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, sampler1Texture);
GLint sampler1Uniform = glGetUniformLocation(programStandard, "sampler2");
glUniform1i(sampler1Uniform, 1);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW / 2, // source width
mFrameH / 2, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
&_frameData[_idxU]);
// V data
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, sampler2Texture);
GLint sampler2Uniform = glGetUniformLocation(programStandard, "sampler1");
glUniform1i(sampler2Uniform, 2);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW / 2, // source width
mFrameH / 2, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
&_frameData[_idxV]);
// Y data
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, sampler0Texture);
GLint sampler0Uniform = glGetUniformLocation(programStandard, "sampler0");
glUniform1i(sampler0Uniform, 0);
glTexSubImage2D(
GL_TEXTURE_2D,
0,
0,
0,
mFrameW, // source width
mFrameH, // source height
GL_LUMINANCE,
GL_UNSIGNED_BYTE,
_frameData);
//draw RECT
glVertexAttribPointer(ATTRIB_VERTEX, 3, GL_FLOAT, 0, 0, squareVertices);
glEnableVertexAttribArray(ATTRIB_VERTEX);
//ATTRIB_TEXTUREPOSITON
glVertexAttribPointer(ATTRIB_TEXTUREPOSITON, 2, GL_FLOAT, 0, 0, textureCoords);
glEnableVertexAttribArray(ATTRIB_TEXTUREPOSITON);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
free(_frameData);
[(EAGLView *)self.view presentFramebuffer];
结论: u< - > v
制服。
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