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I'm recording alot of video files and I need to create real-time peaks of the recorded audio stream. I was thinking that I could achieve this by creating an .AX filter to attach to the recorder graph which will receive the audio stream, analyze it, and create the peaks.
Does anyone have any idea how to implement this?
Thanks alot !
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A good place to start is with the filter samples included with the DirectShow SDK.
The WavDest Filter Sample is an example of a transform filter for audio.
The Scope Filter Sample shows one way of processing audio samples.
Is there a more specific part that you are having trouble implementing?
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
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Thanks alot !
Scope sample is something close of what I need. I just want that result write to a file. Frame number along with peak audio value.
I need a filter that's compatible with iuVCR. The scope filter is not, and I don't know how to implement one that could be used with it.
Claudiu
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The scope filter is a renderer so that would be tough to use unless you insert a tee somewhere
in the graph.
The WavDest filter is implemented as a transform filter, which seems more appropriate for your
needs - you can grab samples as they go by in the graph.
Either way, getting them to work with iuVCR is the problem. I've never used it. What does a
filter graph look like with it? No matter what method you choose, you'll need a place in the
graph to insert your filter (or a tee, then your filter).
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
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I don't know how to take a look at it's filer graph. It has an option to insert additional filters into the filter graph. Here's a quote from the help file "This tab allows the use of additional plugins for real time video stream processing. Any DirectShow filter with one Input Pin and one Output Pin can be used as a plug-in for iuVCR. Compatibility between the current video stream and filter is strongly recommended for correct operation."
As you might suspect I'm a DirectShow novice. Any further help is greatly appreciated 
Claudiu
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Well that's good - at least there's a place to insert filters!  Does it specify just the video
stream or do you have access to the audio stream?
With access to the audio stream, the WavDest Filter Sample would be a good start since it's
implemented as a transform filter - it has one input pin and one output pin.
I'll take a look at iuVCR...
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
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I believe it gives access to audio stream also, I don't see why not.
Or could that be the reason I can't load WaveDest filter ? Because it won't allow access to audio stream?
Perhaps you'll be able to figure it out better when you take a look at it.
Claudiu
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hmm I don't see any audio stream inserts there.
Maybe contact Ivan and ask him to add it! It should be pretty simple
Although it uses directShow, it's an all-in-one app. Unless he provides an insertion point for
external filters (like he has for video) there's no way to get at the filter graph to manually
insert filters.
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
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Thought so... I'll contact him regarding this matter.
Thank you so much for your support. If I'll need more help I'll get back with some more posts .
Claudiu
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How can we save the contents of a Graphics object as a jpg ???
thanks
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How can we combine a transparent GIF image with a JPG file and save the resulting image in disc.
I want the GIF to act as a frame that we can see the JPG image through it . Help me please.
Thanks.
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If you use GDI+ you can load the jpeg, assoiciate it with a Graphics object, and draw the gif
transparently on top of it.
Mark
"If you can dodge a wrench, you can dodge a ball."
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Please don't cross post in multiple forums!
Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007
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In GDI+ in .NET ,How can we load a jpg image from disc and scale it to a smaller size and then save it to disk..
Help me please I need this now .
Thanks.
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Here's one way:
1) Create a System.Drawing.Bitmap of the desired destination pixel format and dimensions
2) Create a destination System.Drawing.Graphics object from the bitmap (using Graphics.FromImage)
2a) *optional* set the InterpolationMode property on the destination Graphics object
3) Load the source image as a System.Drawing.Bitmap
4) Use Graphics.DrawImage to draw the source image on the destination graphics (created in step 2)
5) Save the destination bitmap (created in step 1)
-- modified at 14:17 Tuesday 10th April, 2007
"If you can dodge a wrench, you can dodge a ball."
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Does anyone know, please, how to install this very useful previewer? The code comes with a .txt file but I just don't understand it! It talks about changing paths, which I really don't get. Can anyone help with an explanation in plain English, please? (and help others struggling, too)
Many thanks.
Roy
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In the folder with the dll file, open a command prompt with admin privileges
gacutil -i MsdnMagPreviewHandlers.dll
regasm /codebase MsdnMagPreviewHandlers.dll
gacutil -i PSDPreviewHandlers.dll
regasm /codebase PSDPreviewHandlers.dll
thats it , check by clicking the psd file and view in the preview pane
Omit Needless Words - Strunk, William, Jr.
Vista? Photoshop Preview Handler here
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Hi
Im coding a virtual hair styling and makeover tool in C#. Can any buddy know any link or idea abt virtual makeover.... Any link for the help.......
actually when I apply makeover it should blend the applied color on the skin. How can I get the blended effect?? Wht function I should use on the pixel previos color and the new color to be applied........ ANY Idea?????
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I am looking at the new Vista/07 styles and was wondering what the formula was for creating the gradients.
Brad
Australian
- unknown PHP Developer on "Job Prospect"
Requirement: * Experience working with XML, XSL, XPath
Comment: and other things starting with X.
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I don't understand your question... I noted nothing misterious with Vista's gradients... maybe you mean gradients in color and in transparency? Or are you just asking about gradients in general?
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Yeah just gradients in general. I know nothing of graphics
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Ok.
Modern computer graphics consist of pixels, which are the smallest units of color that can be represented on the screen. A screen of 1280x1024 contains 1.3 million pixels, and a modern display can set each one of those pixels to an individual color.
These pixels are divided into 3 components: the red, the green, and the blue. This is because almost every color that our eyes can distinguish can be obtained by combining diferent amounts of red, green, and blue. So, controlling only these 3 components can make it possible to obtain almost any possible color.
Then there is component resolution. Each component can be varied in intensity to achieve diferent colors, as I mentioned before. Usually we cannot distinguish between more than about 150 steps, meaning that if the span of a given component (from invisible (or off) to its full intensity) is divided into more than about 150 steps then we cannot tell the difference from one step to another. So we don't need to divide the span into more than 150 steps. However we divide it into 256 steps, to make it confortable to store components in computer memory (one byte per component) and for some other not so obvious reasons. This givs us a total of over 16 million individual colors (with 256 steps per component we get a total of 256x256x256 different colors).
To get white you sum all components (you set red, green, and blue, to full intensity). This is the whitest that a screen is able to represent. To get black you turn them all off, and that is the blackest that a screen can represent. Screens vary in their ability to make full white or full black. For example, my video projector is unable to make perfect white because the blue component is a little weaker than the others (as with many of the mid-range video projectors). Also, LCD's/TFT's are unable to make perfect black, usually because the material used for their construction usually reflects some envoronmental light.
If you want a gradient from black to white (from left to right, for example) then you should vary the component intensity from off (to the left) to on (to the right). Imagine an image of 800x600 and the following formula:
for(x=0; x<800; x++) {
for(y=0; y<600; y++) {
pixel(x,y).red=x/799*255;
pixel(x,y).green=x/799*255;
pixel(x,y).blue=x/799*255;
} // next y
} // next x
As you can see, x/799 is 1.0 only when x is 799, and that happens only at the rightmost pixel. Also, x/799 is zero on the left. An inversion would be simple, just replace x/799 by (799-x)/799. Also note that the component intensity does not depend on y, so there are changes only from left to right and not from top to bottom.
If you wanted full white on the top left and full white on the bottom right, the formula would be:
for(x=0; x<800; x++) {
for(y=0; y<600; y++) {
pixel(x,y).red=(x+y)/(799+599)*255;
pixel(x,y).green=(x+y)/(799+599)*255;
pixel(x,y).blue=(x+y)/(799+599)*255;
} // next y
} // next x
Again (x+y)/(799/599) is zero at the top left, and one at the bottom right. At the bottom left it is some intermediate level of gray (between black and white) as well as on the top right. If instead of black to white you wanted black to red then you just keep the green and blue at zero through all the operation.
for(x=0; x<800; x++) {
for(y=0; y<600; y++) {
pixel(x,y).red=(x+y)/(799+599)*255;
pixel(x,y).green=0;
pixel(x,y).blue=0;
} // next y
} // next x
At the top left all components are zero (black) and at the bottom right red is one and the others are zero. Orange is about full red, half gree, and zero blue. To go from black to orange you would do:
for(x=0; x<800; x++) {
for(y=0; y<600; y++) {
pixel(x,y).red=(x+y)/(799+599)*255;
pixel(x,y).green=(x+y)/(799+599)*128;
pixel(x,y).blue=0;
} // next y
} // next x
At the bottom right the pixel is full red, half green, and zero blue.
So, as you can see, the formula is simple after you know what you want. As you can imagine it would be easy to get gradients with many diferent colors by using more elaborate formulas. In general, you just need a function...
GetPixelComponets(float dx, float dy, int& dst_red, int& dst_green, int& dst_blue);
... that takes normalized X/Y coordinates (dx/dy from 0.0 to 1.0 so as not to depend on screen resolution) and computes what the component values dst_red, dst_green, and dst_blue should be for that screen point. Then that function simply has to take some set of references of the colors you want and where (in the above examples I wanted 2 reference points: a given color on the top left and another on the bottom right) and interpolate them (making smooth spatial transitions from a reference point to the next).
I hope this helps,
Rilhas
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Thank you very much for this, it is fantastic advise.
Brad
Australian
- peterchen on "Who has the worst keyboard"
Keyboard? Ha! I throw magnets over the RAM chips!
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Hi
I'm working on a teleprompter software (that flips a given text and lets the user to scroll it pixel by pixel)
I tried GDI+ using C# .Each time the user wants to scroll the text an image of the current lines is made.Then the image is rotated and loaded into a pciture box.
Unfortunately this procedure is very slow.
I like to ask if there is anyway that I can do the same thing using DirectX or OpenGL (I've already searched the ineternet but I couldn't find any answer)
Is there any other way that I can show the text upside down and let the user to scorll it?
Thanks a lot
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