[Solved] Image capture from webcam to jpg.
lazarus / 39-Graphics

----------------------------------------------------------------------
BlueIcaro · 2020-11-23 19:51

Hello, I making a program that connects to a usb webcam using
videodev2 that I get from sdpo package.
I have any problem to capture a frame. But I want to save it as jpg
format.

Code: [Select] repeat
    begin
      FillChar(vBuf, sizeof(v4l2_buffer), 0);
      vbuf._type := V4L2_BUF_TYPE_VIDEO_CAPTURE;
      vbuf.memory := V4L2_MEMORY_MMAP;
      //Capturar imagen
      if DynIoctl(videohandle, VIDIOC_DQBUF, @vbuf) < 0 then
      begin
        raise Exception.Create('Fallo durante la captura');
      end;
    end;

  until vBuf.bytesused > 0;
  VideoBufferIndex := vbuf.index;
  FramePtr := VideoBuffer[VideoBufferIndex];

  Datos := TMemoryStream.Create;
  Datos.SetSize(vHeight * vWidth);
  Datos.Position := 0;
  size := vHeight * vWidth;

  //   case PixelFormat of
  //     uvcpf_YUYV:
  //YUYV_to_Gray  function converted
  for i := 0 to (size div 2) - 1 do
  begin
    g := FramePtr^ and $FF;
    r := g;
    b := g;
    //dest^ := (r shl 16) or (g shl 8) or (b);
    temp := (r shl 16) or (g shl 8) or (b);
    Datos.Write(temp, SizeOf(Temp));


    g := (FramePtr^ shr 16) and $FF;
    r := g;
    b := g;
    //dest^ := (r shl 16) or (g shl 8) or (b);
    temp := (r shl 16) or (g shl 8) or (b);
    Datos.Write(temp, SizeOf(Temp));
    Inc(FramePtr);
    //Inc(dest);
  end;
   
   Imagen := TFPMemoryImage.Create(vWidth,vHeight);
   Imagen.UsePalette:=true;
    MiPaleta.Alpha:=0;
   MiPaleta.Blue:=155;
   MiPaleta.Green:=75;
   MiPaleta.Red:=56;
   f := Imagen.Palette.Add(MiPaleta);
   DAtos.Position:=0;
   For X:= 0 To Imagen.Width-1 do
   begin
      For Y := 0 To Imagen.Height-1 do
      begin
        pixel := Datos.ReadByte;
        Imagen.Pixels[x,y] := pixel;
      end;
   end;

  //   case PixelFormat of
  //     uvcpf_YUYV:
  //       YUYV_to_Gray(PLongWord(FramePtr), (pdatos),
  //         vWidth * vHeight);
  //     uvcpf_YUV420:
  //       YUV420_to_Gray(FramePtr,  (pdatos), vWidth * vHeight);
  //     uvcpf_RGB24:
  //       RGB24_to_TrueColor(PRGB24Pixel(FramePtr),  (pdatos), vWidth
* vHeight);
  //     uvcpf_BGR24:
  //       BGR24_to_TrueColor(PRGB24Pixel(FramePtr),  (pdatos), vWidth
* vHeight);
  //   end;

     j := TFPWriterJPEG.Create;
     j.CompressionQuality:=75;
    Imagen.SaveToFile('pepe.jpg',j);
                                                                     
                 

In this code, I got a image from camera, and I convert to 
YUYV_to_Gray and store into TMemorystream. But I'm lost with palette.
I think I should create 255 palettes, which  values?. Or there is
other way to do the job?.

I attach all code.
Programmed in Linux 20.04 and Lazarus 2.10

Thanks in advance

/BlueIcaro

----------------------------------------------------------------------
circular · 2020-11-23 21:34

You can make a grayscale palette with a loop with i from 0 to 255,
setting Red, Green and Blue to I*$0101 and alpha to $ffff

----------------------------------------------------------------------
Jurassic Pork · 2020-11-24 00:21

hello,
if you have mplayer installed in your O.S and you  make a graphical
program, have a look
 here  and here

Friendly, J.P

----------------------------------------------------------------------
BlueIcaro · 2020-11-24 17:40

Quote from: Jurassic Pork on November 24, 2020, 01:21:49 amhello,
if you have mplayer installed in your O.S and you  make a graphical
program, have a look
 here  and here

Friendly, J.P

The program will run in a linux without GUI.

/BlueIcaro

----------------------------------------------------------------------
BlueIcaro · 2020-11-25 15:19

Hello, I make some changes in the program. I can save a jpeg image.
But my image is not equal to original is like rotate and cutted.

This the code that I use to capture:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  procedure
GuardarImagen; var  vBuf: v4l2_buffer;  VideoBufferIndex: __u32; 
FramePtr: PByte;  x, y, i, size, f: integer;  Datos: TMemoryStream; 
Imagen: TFPMemoryImage;  MiPaleta: TFPColor;  j: TFPWriterJPEG; 
Convertido, src: PRGB24Pixel;  Blue, Green, Red, g, r, b: byte;  h,
by, pixel: longint;  d, RgbColor: longword;  buffer: TRGB24Pixel; 
color: TColor;  dest: Pointer; begin  repeat    begin     
FillChar(vBuf, sizeof(v4l2_buffer), 0);      vbuf._type :=
V4L2_BUF_TYPE_VIDEO_CAPTURE;      vbuf.memory := V4L2_MEMORY_MMAP;   
 //Capturar imagen      if DynIoctl(videohandle, VIDIOC_DQBUF, @vbuf)
< 0 then      begin        raise Exception.Create('Fallo durante la
captura');      end;    end;   until vBuf.bytesused > 0; 
Sleep(2000);  VideoBufferIndex := vbuf.index;  FramePtr :=
VideoBuffer[VideoBufferIndex];   Datos := TMemoryStream.Create; 
//Datos.SetSize(vHeight * vWidth);  Datos.Position := 0;  size :=
vHeight * vWidth * 3;   case PixelFormat of    uvcpf_YUYV:     
writeln('uvcpf_YUYV');    uvcpf_YUV420:      writeln('uvcpf_YUV420'); 
  uvcpf_RGB24:      writeln('uvcpf_RGB24');    uvcpf_BGR24:     
WriteLn('uvcpf_BGR24');  end;    //convers format uvcpf_BGR24  src :=
PRGB24Pixel(FramePtr);  for I := 0 to size - 1 do  begin    RgbColor
:= PLongWord(@src[I])^;    datos.Write(RgbColor,1);  end;   Imagen :=
TFPMemoryImage.Create(vWidth, vHeight);   Imagen.UsePalette := True; 
for I := 0 to 255 do  begin    MiPaleta.Alpha := $FFFF;   
MiPaleta.Blue := I * $0101;    MiPaleta.Green := I * $0101;   
MiPaleta.Red := I * $0101;     f := Imagen.Palette.Add(MiPaleta); 
end;     Datos.Position := 0;  for X := 0 to Imagen.Width - 1 do 
begin    for Y := 0 to Imagen.Height - 1 do    begin     
Datos.Read(RgbColor,1);      Imagen.Pixels[x, y] := RgbColor;    end; 
end;     j := TFPWriterJPEG.Create;  j.CompressionQuality := 100; 
Imagen.SaveToFile('pepe.jpg', j);end;          I attach the program
complete. And two image. The "original" and the image that saves my
program Any IdeaThanks/BlueIcaro

----------------------------------------------------------------------
circular · 2020-11-25 15:31

I suppose pixels are organized as rows, so:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Datos.Position := 0;  for Y := 0 to Imagen.Height - 1 do  begin    for
X := 0 to Imagen.Width - 1 do    begin      Datos.Read(RgbColor,1);  
  Imagen.Pixels[x, y] := RgbColor;    end;  end;

----------------------------------------------------------------------
BlueIcaro · 2020-11-25 15:46

Amazing Circular!!!
I was fighting with Tmemoruimage, and the tstreammemory, because I
thought that the problem was when the programs moved the info from
image buffer.
Also I thought that the program leaved the repeat until loop before
image was complete.
I spend this days reading about linux driver  ( 
https://linuxtv.org/docs.php )  

I didn't see that the rows are changed by cols 

Two fast (i hope) questions more:
How can I make a palette with the colors?
Where Can I find more info about colors, palettes, etc?

Thanks

/BlueIcaro

P.D I attach the image with Circular solution. The image is not the
same that the previous post, because I moved the camera.

----------------------------------------------------------------------
circular · 2020-11-25 16:43

Basically you don't need to use the intermediate memory stream Datos
nor Palette. You can set the RGB values directly:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var fpCol:
TFPColor;...  Imagen := TFPMemoryImage.Create(vWidth, vHeight);  src
:= PRGB24Pixel(FramePtr);  fpCol.alpha := $ffff;  for Y := 0 to
Imagen.Height - 1 do    for X := 0 to Imagen.Width - 1 do    begin   
 fpCol.red := src^.red * $101;      fpCol.green := src^.green * $101; 
    fpCol.blue := src^.blue * $101;      Imagen.Colors[x, y] :=
fpCol;      inc(src);    end;  ...  Imagen.Free; // don't forget to
free memory

----------------------------------------------------------------------
BlueIcaro · 2020-11-26 20:04

Thank you very match for all
/BlueIcaro