How to take snapshot and save to JPEG from webcam using DSPack? - delphi

Question

Using DSPack, Delphi XE I need to take a snapshot from a webcam and allow a preview before which the user is allowed to save to JPEG file. How can this be done (code)?

Answer 1

Maybe this will work, but I have not tested it. You should give it a try.
unit main;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, DSPack, DSUtil, DirectShow9;
type
TMainForm = class(TForm)
CaptureGraph: TFilterGraph;
VideoWindow: TVideoWindow;
ListBox1: TListBox;
VideoSourceFilter: TFilter;
StartButton: TButton;
StopButton: TButton;
Label1: TLabel;
ListBox2: TListBox;
Label3: TLabel;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure ListBox1Click(Sender: TObject);
procedure StartButtonClick(Sender: TObject);
procedure StopButtonClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
MainForm: TMainForm;
VideoDevice: TSysDevEnum;
VideoMediaTypes: TEnumMediaType;
implementation
{$R *.dfm}
{ TMainForm }
procedure TMainForm.FormCreate(Sender: TObject);
var i: integer;
begin
VideoDevice := TSysDevEnum.Create(CLSID_VideoInputDeviceCategory);
for i := 0 to VideoDevice.CountFilters - 1 do
ListBox1.Items.Add(VideoDevice.Filters[i].FriendlyName);
VideoMediaTypes := TEnumMediaType.Create;
end;
procedure TMainForm.FormDestroy(Sender: TObject);
begin
VideoDevice.Free;
VideoMediaTypes.Free;
end;
// Selecting of the video source
procedure TMainForm.ListBox1Click(Sender: TObject);
var
PinList: TPinList;
i: integer;
begin
VideoDevice.SelectGUIDCategory(CLSID_VideoInputDeviceCategory);
if ListBox1.ItemIndex <> -1 then
begin
// Set the device which we work with
VideoSourceFilter.BaseFilter.Moniker := VideoDevice.GetMoniker(ListBox1.ItemIndex);
VideoSourceFilter.FilterGraph := CaptureGraph;
CaptureGraph.Active := true;
PinList := TPinList.Create(VideoSourceFilter as IBaseFilter);
ListBox2.Clear;
VideoMediaTypes.Assign(PinList.First);
// Adding permission to ListBox2, which supports device
for i := 0 to VideoMediaTypes.Count - 1 do
ListBox2.Items.Add(VideoMediaTypes.MediaDescription[i]);
CaptureGraph.Active := false;
PinList.Free;
StartButton.Enabled := true;
end;
end;
procedure TMainForm.StartButtonClick(Sender: TObject);
var
PinList: TPinList;
begin
// Activating graph filter, at this stage the source filter is added to the graph
CaptureGraph.Active := true;
// The configuration of the output device
if VideoSourceFilter.FilterGraph <> nil then
begin
PinList := TPinList.Create(VideoSourceFilter as IBaseFilter);
if ListBox2.ItemIndex <> -1 then
with (PinList.First as IAMStreamConfig) do
SetFormat(VideoMediaTypes.Items[ListBox2.ItemIndex].AMMediaType^);
PinList.Free;
end;
// now render streams
with CaptureGraph as IcaptureGraphBuilder2 do
begin
// Hooking up a preview video (VideoWindow)
if VideoSourceFilter.BaseFilter.DataLength > 0 then
RenderStream(#PIN_CATEGORY_PREVIEW, nil, VideoSourceFilter as IBaseFilter,
nil , VideoWindow as IBaseFilter);
end;
// Launch video
CaptureGraph.Play;
StopButton.Enabled := true;
StartButton.Enabled := false;
ListBox2.Enabled := false;
ListBox1.Enabled := false;
end;
// Stop video
procedure TMainForm.StopButtonClick(Sender: TObject);
begin
StopButton.Enabled := false;
StartButton.Enabled := true;
CaptureGraph.Stop;
CaptureGraph.Active := False;
ListBox2.Enabled := true;
ListBox1.Enabled := true;
end;
end.