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• FFMPEG error : Error while parsing expression 'PTS-STARTPTS+/TB' while trying to merge two videos with different starting time [closed]

  13 octobre 2020, par Sankalpa Sarkar

  I was trying to merge two videos in .webm format side-by-side, with the exception that the second video might start a bit later than the first video, in which case there will be a blank buffer on the right side till it starts. To do that, I deployed the following code :

  


     DIFF=$(($start_ts-$BASEts))
   DIFFms=`echo "scale=0;$DIFF/1000" | bc`
   DIFFs=`echo "scale=4;$DIFF/1000000" | bc`
   ffmpeg -i a.webm -i b.webm -filter_complex \
    "[0]pad=2*iw:1*ih[l];[1]setpts=PTS-STARTPTS+$DIFFs/TB[1v]; [l][1v]overlay=x=W/2[v]; \
    [1]adelay=$DIFFms|$DIFFms[1a]; \
    [0][1a]amix=inputs=2[a]" \
    -map "[v]" -map "[a]" -vcodec libvpx -cpu-used -5 -deadline realtime finalOutput.webm


  


  However, I keep getting this error :

  


  [Parsed_setpts_1 @ 0x5598b680cdc0] [Eval @ 0x7ffcb6ae1550] Undefined constant or missing '(' in '/TB'
[Parsed_setpts_1 @ 0x5598b680cdc0] Error while parsing expression 'PTS-STARTPTS+/TB'
[AVFilterGraph @ 0x5598b67872a0] Error initializing filter 'setpts' with args 'PTS-STARTPTS+/TB'
Error initializing complex filters.
Invalid argument


  


  It is not recognizing the DIFFs variable at all and is hence unable to process the code. I tried replacing the entire setpts in a different variable as well and using it in setpts while merging. That process did not work either

  


• Decoded YUV shows green edge when rendered with OpenGL

  2 février 2023, par Alex

  Any idea, why decoded YUV -> RGB(shader conversion) has that extra green edge on the right side ?
  
Almost any 1080X1920 video seems to have this issue.

  


  

  


  A screen recording of the issue is uploaded here https://imgur.com/a/JtUZq4h

  


  Once I manually scale up the texture width, I can see it fills up to the viewport, but it would be nice if I could fix the actual cause. Is it some padding that's part of YUV colorspace ? What else could it be ?

  


  My model is -1 to 1, filling the entire width
  
The texture coordinates are also 0 to 1 ratio

  


  float vertices[] = {
    -1.0, 1.0f, 0.0f, 0.0,     // top left
     1.0f, 1.0f, 1.0, 0.0,      // top right
    -1.0f, -1.0f, 0.0f, 1.0f,  // bottom left
     1.0f, -1.0f, 1.0f, 1.0f    // bottom right
};


  


  Fragment Shader

  


  #version 330 core

in vec2 TexCoord;

out vec4 FragColor;
precision highp float;
uniform sampler2D textureY;
uniform sampler2D textureU;
uniform sampler2D textureV;
uniform float alpha;
uniform vec2 texScale;


void main()
{
    float y = texture(textureY, TexCoord / texScale).r;
    float u = texture(textureU, TexCoord / texScale).r - 0.5; 
    float v = texture(textureV, TexCoord / texScale).r - 0.5;
    
    vec3 rgb;
    
    //yuv - 709
    rgb.r = clamp(y + (1.402 * v), 0, 255);
    rgb.g = clamp(y - (0.2126 * 1.5748 / 0.7152) * u - (0.0722 * 1.8556 / 0.7152) * v, 0, 255);
    rgb.b = clamp(y + (1.8556 * u), 0,255);

    FragColor = vec4(rgb, 1.0);
} 


  


  Texture Class

  


  class VideoTexture {
   public:
    VideoTexture(Decoder *dec) : decoder(dec) {
        glGenTextures(1, &texture1);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glBindTexture(GL_TEXTURE_2D, texture1);
        glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, decoder->frameQueue.first().linesize[0], decoder->frameQueue.first().height, 0, format, GL_UNSIGNED_BYTE, 0);
        glGenerateMipmap(GL_TEXTURE_2D);

        glGenTextures(1, &texture2);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glBindTexture(GL_TEXTURE_2D, texture2);
        glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, decoder->frameQueue.first().linesize[1], decoder->frameQueue.first().height / 2, 0, format, GL_UNSIGNED_BYTE, 0);
        glGenerateMipmap(GL_TEXTURE_2D);

        glGenTextures(1, &texture3);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glBindTexture(GL_TEXTURE_2D, texture3);
        glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, decoder->frameQueue.first().linesize[2], decoder->frameQueue.first().height / 2, 0, format, GL_UNSIGNED_BYTE, 0);
        glGenerateMipmap(GL_TEXTURE_2D);
    }

    void Render(Shader *shader, Gui *gui) {
        if (decoder->frameQueue.isEmpty()) {
            return;
        }

        glActiveTexture(GL_TEXTURE0);
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, decoder->frameQueue.first().linesize[0], decoder->frameQueue.first().height, format, GL_UNSIGNED_BYTE, decoder->frameQueue.at(currentFrame).data[0]);
        glBindTexture(GL_TEXTURE_2D, texture1);
        shader->setInt("textureY", 0);

        glActiveTexture(GL_TEXTURE1);
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, decoder->frameQueue.first().linesize[1], decoder->frameQueue.first().height / 2, format, GL_UNSIGNED_BYTE, decoder->frameQueue.at(currentFrame).data[1]);
        glBindTexture(GL_TEXTURE_2D, texture2);
        shader->setInt("textureU", 1);

        glActiveTexture(GL_TEXTURE2);
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, decoder->frameQueue.first().linesize[2], decoder->frameQueue.first().height / 2, format, GL_UNSIGNED_BYTE, decoder->frameQueue.at(currentFrame).data[2]);
        glBindTexture(GL_TEXTURE_2D, texture3);
        shader->setInt("textureV", 2);
    }

    ~VideoTexture() {
        printf("\nVideo texture destructor");
        glDeleteTextures(1, &texture1);
        glDeleteTextures(1, &texture2);
        glDeleteTextures(1, &texture3);
    }

   private:
    GLuint texture1;
    GLuint texture2;
    GLuint texture3;
    GLint internalFormat = GL_RG8;
    GLint format = GL_RED;
    int currentFrame = 0;
    Decoder *decoder;
}


  


• FFmpeg - Xstack mutiple inputs for mosaic video output - extra output Blank screen is always green

  16 août 2020, par Dennisski

  I have a website where we combine multple videos with ffmpeg xstack. Its an automated process. When there is not an even number of videos the blank tiles in the mosaic are green. I am trying to figure out how to make the spare blanks Black.

  


  I have tried xstack=inputs=2:fill='black':layout=0_0 (this gives an error object not found) also tried -filter_complex "color=s=1920x1080:c=black".

  


  Any suggestions ? Here is entire command :

  


  ffmpeg -i video1 -i video1 -i video1 -i video1 -i video1 -i video1 -i video1 \ 
    -i video1 -i video1 -filter_complex \
    "color=s=1920x1080:c=black;[0:v] setpts=PTS-STARTPTS, scale=qvga [a0];[1:v] setpts=PTS-STARTPTS, scale=qvga [a1];[2:v] setpts=PTS-STARTPTS, scale=qvga [a2];[3:v] setpts=PTS-STARTPTS, scale=qvga [a3];[4:v] setpts=PTS-STARTPTS, scale=qvga [a4];[5:v] setpts=PTS-STARTPTS, scale=qvga [a5];[6:v] setpts=PTS-STARTPTS, scale=qvga [a6];[7:v] setpts=PTS-STARTPTS, scale=qvga [a7];[8:v] setpts=PTS-STARTPTS, scale=qvga [a8];[a0][a1][a2][a3][a4][a5][a6][a7][a8]xstack=inputs=9:layout=0_0|w0_0|w0+w1_0|0_h0|w0_h0|w0+w1_h0|0_h0+h1|w0_h0+h1|w0+w1_h0+h1[out] " \
    -map "[out]" output