program scaling_video;

{$APPTYPE CONSOLE}
{$R *.res}
{$include ffmpeg.inc}

uses
  System.SysUtils,
  System.Classes,
  ffmpeglib in '..\..\ffmpeglib.pas',
  libavcodec.avcodec in '..\..\libavcodec\libavcodec.avcodec.pas',
  ctypes in '..\..\..\ctypes\ctypes.pas',
  avformat in '..\..\libavformat\avformat.pas',
  avio in '..\..\libavformat\avio.pas',
  avutil in '..\..\libavutil\avutil.pas',
  buffer in '..\..\libavutil\buffer.pas',
  dict in '..\..\libavutil\dict.pas',
  frame in '..\..\libavutil\frame.pas',
  log in '..\..\libavutil\log.pas',
  opt in '..\..\libavutil\opt.pas',
  pixfmt in '..\..\libavutil\pixfmt.pas',
  rational in '..\..\libavutil\rational.pas',
  samplefmt in '..\..\libavutil\samplefmt.pas',
  parseutils in '..\..\libavutil\parseutils.pas',
  swscale in '..\..\libswscale\swscale.pas',
  pixdesc in '..\..\libavutil\pixdesc.pas',
  imgutils in '..\..\libavutil\imgutils.pas',
  mem in '..\..\libavutil\mem.pas',
  error in '..\..\libavutil\error.pas';

Var
  src_data: TPointers;
  dst_data: TPointers;
  src_linesize: TLinesizes;
  dst_linesize: TLinesizes;
  src_w: Integer = 320;
  src_h: Integer = 240;
  dst_w, dst_h: Integer;
  src_pix_fmt: TAVPixelFormat = AV_PIX_FMT_YUV420P;
  dst_pix_fmt: TAVPixelFormat = AV_PIX_FMT_RGB24;
  dst_size: AnsiString;
  dst_filename: AnsiString;
//  dst_file: File;
  dst_straem:TMemoryStream;
  dst_bufsize: Integer;
  sws_ctx: pSwsContext = nil;
  i, ret: Integer;

procedure fill_yuv_image(data: TPointers; linesize: TLinesizes; width: Integer; height: Integer; frame_index: Integer);
Var
  x, y: Integer;
begin
  (* Y *)
  for y := 0 to height - 1 do
    for x := 0 to width - 1 do
      data[0][y * linesize[0] + x] := x + y + frame_index * 3;

  (* Cb and Cr *)
  for y := 0 to height div 2 - 1 do
  begin
    for x := 0 to width div 2 - 1 do
    begin
      data[1][y * linesize[1] + x] := 128 + y + frame_index * 2;
      data[2][y * linesize[2] + x] := 64 + x + frame_index * 5;
    end;
  end;
end;

Var
  Buf: array [0 .. 511] of AnsiChar;
  r:Integer;

begin
  try
    if (ParamCount <> 2) then
    begin
      WriteLn(Format('Usage: %s output_file output_size' + #13#10 + 'API example program to show how to scale an image with libswscale.' +
        #13#10 + 'This program generates a series of pictures, rescales them to the given ' +
        'output_size and saves them to an output file named output_file.' + #13#10 + #13#10, [ExtractFileName(ParamStr(0))]));
      Halt(1);
    end;
    dst_filename := ParamStr(1);
    dst_size := ParamStr(2);

    if av_parse_video_size(dst_w, dst_h, PAnsiChar(dst_size)) < 0 then
    begin
      WriteLn(Format('Invalid size %s, must be in the form WxH or a valid size abbreviation', [dst_size]));
      Halt(1);
    end;

//    Assign(dst_file, dst_filename);
//    Rewrite(dst_file,1);
    // if (!dst_file) begin
    // fprintf(stderr, 'Could not open destination file %s'+#13#10+, dst_filename);
    // exit(1);
    // end;

    (* create scaling context *)
    sws_ctx := sws_getContext(src_w, src_h, src_pix_fmt, dst_w, dst_h, dst_pix_fmt, SWS_BILINEAR, Nil, Nil, Nil);
    if not Assigned(sws_ctx) then
    begin
      WriteLn(Format('Impossible to create scale context for the conversion fmt:%s s:%dx%d -> fmt:%s s:%dx%d' + #13#10,
        [av_get_pix_fmt_name(src_pix_fmt), src_w, src_h, av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h]));
      Halt(1);
      // ret := AVERROR(EINVAL);
      // goto
      // end;
    end;

    (* allocate source and destination image buffers *)
    ret := av_image_alloc(src_data, src_linesize, src_w, src_h, src_pix_fmt, 16);
    // av_strerror(ret,@buf,SizeOf(buf));
    if (ret < 0) then
    begin
      WriteLn('Could not allocate source image');
      Halt(1);
    end;

    (* buffer is going to be written to rawvideo file, no alignment *)
    ret := av_image_alloc(dst_data, dst_linesize, dst_w, dst_h, dst_pix_fmt, 1);
    if (ret < 0) then
    begin
      WriteLn('Could not allocate destination image');
    end;
    dst_bufsize := ret;

    dst_straem:=TMemoryStream.Create;

    for i := 0 to 99 do
    begin
      (* generate synthetic video *)
      fill_yuv_image(src_data, src_linesize, src_w, src_h, i);

      (* convert to destination format *)
      sws_scale(sws_ctx, @src_data, @src_linesize, 0, src_h, @dst_data, @dst_linesize);

      (* write scaled image to file *)
      dst_straem.Write((@dst_data[0][0])^, dst_bufsize);
    end;

    dst_straem.SaveToFile(dst_filename);
    dst_straem.Free;

    WriteLn(Format('Scaling succeeded. Play the output file with the command:' + #13#10 +
      'ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s', [av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename]));

    av_freep(@src_data[0]);
    av_freep(@dst_data[0]);
    sws_freeContext(sws_ctx);

  except
    on E: Exception do
      WriteLn(E.ClassName, ': ', E.Message);
  end;

end.