Desperate to Overlay Moving Text over Video

[guivetemp]

I have spent MONTHS working on this problem.
I am trying to create a program that will overlay a static text/image AND a moving text (like a ticker) on top of an existing video

I am using DirectshowNet with VMR-9

The issue is that the bitmap mixer of VMR9 requires a pointer to

alphaBitmap = New Bitmap(720, 256)
g= Graphics.FromImage(alphaBitmap)

Then I have a timer that executes several time per second and which scrolls the text as:

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Static Dim hr As Integer = 0
Static Dim vez = 0

    Static Dim pos As Double



    Dim b As Brush
    b = New SolidBrush(Color.FromArgb(255, 100, 100, 240))


    Dim f As New Font("Arial", 24, FontStyle.Bold, GraphicsUnit.Pixel)


    Dim NativeMethodes As bmpMixerVB.DirectShowLib.Sample.NativeMethodes
    Dim r As New Rectangle(0, 0, 720, 576)
   g.Clear(Color.FromArgb(50, 255, 100, 100))
    g.DrawString("HELLO BABES", f, Brushes.Tomato, 0, 0)


    surface = New Surface(device, alphaBitmap, Pool.SystemMemory)

    unmanagedSurface = surface.GetObjectByValue(DxMagicNumber)


    pos = pos + 0.02
    Dim alphaBmp As VMR9AlphaBitmap
    alphaBmp = New VMR9AlphaBitmap
    alphaBmp.dwFilterMode = VMRMixerPrefs.PointFiltering
    alphaBmp.dwFlags = VMR9AlphaBitmapFlags.EntireDDS
    alphaBmp.pDDS = unmanagedSurface
    alphaBmp.rDest = GetDestRectangle()
    alphaBmp.rDest.top = 0
    alphaBmp.rDest.bottom = 1
    alphaBmp.rDest.right = pos + 3
    alphaBmp.rDest.left = pos
      alphaBmp.fAlpha = 1.0F

    hr = mixerBitmap.SetAlphaBitmap(alphaBmp)

    surface.Dispose()


    If pos > 1 Then pos = 0



End Sub

The big issue is that each time the timer is called I am doing

surface = New Surface(device, alphaBitmap, Pool.SystemMemory)

and this is a huge overkill. If I leave the surface as global variable and do not make the above call , even if I update unmanagedSurface = surface.GetObjectByValue(DxMagicNumber) , Then there is no update of the image.

My question: is there a way to push by updated bitmap to the VMR9 mixer without requiring to create a new Direct3D everytime.

Note that only a small portion of the surface is modified everytime so I could replace only part of the surface…

So many thanks for anybody who could help

Guive
guivetemp@yahoo.com

[guivetemp]

Zoltan,

I could make good progress. But now I am facing the following issue:
When I try to overlay the text WITH LARGE FONTS ( I am writing a TV Application) on top of the window, the text quality is poor. I tried to play with texthintering and graph smooting parameter. but nothing makes. The perimeter of the text is always kind "dirty": sometimes even there is a connection between two adjacent letters.

any idea what could be going wrong?

[Zoltan Lorincz]

Hello Guive,

unfortunatly i don't know what may be the problem.

Best regards,
Zoltan.

[Eric]

Which technology do you use to write your text (GDI or Direct3D) ?

GDI bitmaps don't support alpha values so colorkey is the only solution to do tansparency and this generaly produce very dirty things (especially with texts). Direct3D surfaces with alpha values & anti-aliased test generally produce better results.

[Zoltan Lorincz]

Hello Guivetemp,

i am a DirectShow newbie, so maybe my advice won't help. However i consider that you shouldn't create a new bitmap at each time the timer is called, only to change the destination rectangle of the VMR9AlphaBitmap. New bitmap should be created every time when the text is changing.

Hope it helps.

Regards,
Zollor.

[Zoltan Lorincz]

Hello Guive,

i found a method to modify the bitmap without recreating the device. Please note that my example is in C#, but you can easily convert to VB.

---

private void _Timer_Tick(object sender, EventArgs e)
{
long startTicks = DateTime.Now.Ticks;
try
{
GraphicsStream stream = surface.LockRectangle(LockFlags.Discard);

            try
            {
                int             stride = alphaBitmap.Width  * 4;

                Bitmap bmp = new Bitmap(
                    alphaBitmap.Width, 
                    alphaBitmap.Height, 
                    stride, 
                    alphaBitmap.PixelFormat, 
                    stream.InternalData
                    );

                using(Graphics gr = Graphics.FromImage(bmp))
                {
                    gr.Clear(Color.Transparent);
                    //gr.DrawString("Test", new Font("Arial", 12), Brushes.Black,  );
                    gr.FillEllipse(Brushes.Blue, this.xCoord, 0, 100, 100);
                    xCoord +=1;
                    if(xCoord > 400) xCoord = 0;
                }
            }
            finally
            {
                surface.UnlockRectangle();

            }

            // Set Alpha Bitmap Parameters for using a Direct3D surface
            VMR9AlphaBitmap alphaBmp = new VMR9AlphaBitmap();
            alphaBmp.dwFlags = VMR9AlphaBitmapFlags.EntireDDS;
            alphaBmp.pDDS = unmanagedSurface;
            alphaBmp.rDest = new NormalizedRect(0,0.8f, 1.0f, 1.0f);//GetDestRectangle();
            alphaBmp.fAlpha = 1.0f;
            // Note : Alpha values from the bitmap are cumulative with the fAlpha parameter.
            // Example : texel alpha = 128 (50%) & fAlpha = 0.5f (50%) = effective alpha : 64 (25%)

            // Set Alpha Bitmap Parameters
            int hr = mixerBitmap.SetAlphaBitmap(ref alphaBmp);
            DsError.ThrowExceptionForHR(hr);
        }
        catch(Exception exc)
        {
            Console.WriteLine(exc);
        }
        Console.WriteLine("Ellapsed ticks: " + (long)(DateTime.Now.Ticks - startTicks));
    }

---

The performance looks good.

Let me know if this helped...

[guivetemp]

Hi Zollor,

So many thanks ! I translated the code in VB and managed to get it to work. I had to add however in the code

Static surface = New Surface(device, alphaBitmap, Pool.SystemMemory)
unmanagedSurface = surface.GetObjectByValue(DxMagicNumber)

You help was really really great. Without it, I would still be stuck !

Private Sub Timer4_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer4.Tick
Dim startTicks As Long = DateTime.Now.Ticks
Static Dim xcoord As Integer

    Static surface = New Surface(device, alphaBitmap, Pool.SystemMemory)


    Try
        Dim stream As GraphicsStream = surface.LockRectangle(LockFlags.Discard)
        Try
            Dim stride As Integer = alphaBitmap.Width * 4
            Dim bmp As Bitmap = New Bitmap(alphaBitmap.Width, alphaBitmap.Height, stride, alphaBitmap.PixelFormat, stream.InternalData)
            ' Using 
            Dim gr As Graphics = Graphics.FromImage(bmp)
            Dim sb As SolidBrush
            sb = New SolidBrush(Color.FromArgb(50, 200, 200, 40))

            Try
                gr.Clear(Color.Transparent)
                gr.FillEllipse(sb, xcoord, 0, 400, 400)
                xcoord += 3
                If xcoord > 400 Then
                    xcoord = 0
                End If
            Finally
                CType(gr, IDisposable).Dispose()
            End Try
        Finally
            surface.UnlockRectangle()
        End Try


        unmanagedSurface = surface.GetObjectByValue(DxMagicNumber)

        Dim alphaBmp As VMR9AlphaBitmap = New VMR9AlphaBitmap
         alphaBmp.rDest = New NormalizedRect(0, 0.8F, 1.0F, 1.0F)
        alphaBmp.dwFilterMode = VMRMixerPrefs.PointFiltering
        alphaBmp.dwFlags = VMR9AlphaBitmapFlags.EntireDDS
        alphaBmp.pDDS = unmanagedSurface
        alphaBmp.rDest.top = 0
        alphaBmp.rDest.bottom = 1
        alphaBmp.rDest.right = 3
        alphaBmp.rDest.left = 0
        alphaBmp.fAlpha = 1.0F

        Dim hr As Integer = mixerBitmap.SetAlphaBitmap(alphaBmp)



        DsError.ThrowExceptionForHR(hr)
    Catch exc As Exception
        Console.WriteLine(exc)
    End Try
    Console.WriteLine("Ellapsed ticks: ", CType((DateTime.Now.Ticks - startTicks), Long))

End Sub

[Zoltan Lorincz]

Hello Guive,

i am happy that i could help ;).

However, don't forget that if you will resize the player window, you will have to reset the device and recreate the surface, at least this is how i could solve the device lost issue.

Regards,
Zollor.

[guivetemp]

Aha !

This may explain why I get sometimes nullexceptions...