I have written a WPF application that can open, edit and render .GRF files. When rendering, I did not want it to open a new window (like GraphEdit does), so I found a solution that uses the Sample Grabber to render samples into a WPF brush.
Before rendering, my application replaces the Video Renderer in the .GRF file with the SampleGrabber. This worked fine, until I met the Microsoft DTV-DVD Video Decoder. For some reason, it only connects to the Video Renderer, and NOT to my Sample Grabber... so currently my application can't handle MPEG2.
Can someone explain to me: why? What restricts these filters from connecting?
And how am I supposed to grab decoded MPEG2 samples then?
Sample Grabber Filter will only connect to video media types described by VIDEOINFOHEADER structure (check MSDN link for details on that in Remarks section). You have video output with MPEG2VIDEOINFO and Sample Grabber rejects it.
Old SDKs have source code for Sample Grabber-like filter, which you can improve to add support for missing format structures. Sample Grabber filter alone is pretty simple on its own. You can also fit some additional decoder (third party, freeware, deinterlacer etc) for it to bring you VIDEOINFOHEADER media type on its output.
Related
I'd like to create to some custom visualization effects to a sound wave in Silverlight. As of Silverlight 3 there's the MediaElement class which does a great job in playing sounds/videos.
To visualize however I would need some kind of event callback with some information on the currently played segment of the sound. Does the framework have some support for achieving this?
I wanted the same so I've created exactly that.
You can see a live demo at http://prefix.teddywino.com/post/SilverlightMediaKitLiveDemo.aspx
The library and demo source code are available at http://salusemediakit.codeplex.com/
The demo shows the added feature to alter the raw audio data to create effects.
Currently works only with MP3s and is still under development
Sadly this is not possible in Silverlight unless you go the whole way and create your own MediaStreamSource to decode the audio (e.g. from MP3) yourself.
Can you get away with cheating? A lot of web players show a fake graphic equaliser which just has bars going up and down randomly during playback. I seem to remember that MySpace and SoundClick used to do this (may still do).
If you implement a custom MediaStreamSource, you could potentially inspect/analyze the data being generated by it, but you will immediately run in to UI threading issues if you try and update the UI directly from the custom MediaStreamSource, or vice versa.
One way to get this to work might be to implement a custom MediaStreamSource that writes (or duplicates?) extra audio data to a thread-safe buffer where your UI could access it.
I was wondering if there was a way to programmatically retrieve the first frame of an AVI and get a bitmap image to show the user a preview. The MediaControl in Silverlight shows a preview for Silverlight supported video files but not AVI. Because I'm in a Silverlight environment I cannot use unmanaged code or libraries to do so. I only have access to the filestream.
The Silverlight runtime doesn't have support for AVI files natively so you won't be able to use those with the MediaElement.
What you would need to do is actually parse the AVI file by hand and pull out frames from that file. Once you get to the point where you are parsing frames, it potentially gets a little trickier.
If you plan on having this work on Silverlight 2, your AVI file would need to contain WMV frames or frames in one of Silverlight's supported image formats(JPG or PNG). If you were working with WMV, I would set up a MediaStreamSource and pass in the desired video frame to the MediaStreamSource as my first sample. If you are working with one of the image formats you should use Image and set its source to a stream. You can see an example where Joe Stegman has used this to help Silverlight 2 support non-native image formats.
If you were doing this in Silverlight 3 (it's in Beta right now) the techniques are generally the same but the media format support grows a bit to include (in addition to WMV): H264, Raw YV12, or Raw ARGB frames. Similarly on the imaging front, you now have the WriteableBitmap which you could use to draw your frame.
If your video is something like Theora, Divx, Xvid, VP6, etc. You would need to find a way to decode that frame so you could display it in Silverlight.
Similar question has been posted on the Silverlight forum. The forum thread includes code samples.
You might want to pick a frame further into the video since the first few frames might fade in, or not be very representative of the video.
Depending on the encoding, your AVI files might not be readable by the MediaPlayer class. (See here for compatible encodings). You might need to transcode the video to do this with managed code. Unless you find/write your own decoder.
I am trying to evaluate which technology is best for my needs.
I need to display a video I get from some remote device, and let a user
interactively draw on it lines, polygons etc.
I searched and couldn't find any existing applications with this ability
(all the flash applications only displayed video).
Could anyone point me to such an application?
I haven't seen a specific app that allows you to do that, but I can tell you it would be fairly trivial to build it in Flex. You would simply create a transparent Sprite over the video clip, then use the Drawing API bound to various mouse events to do your drawing.
The final image can be saved by using BitmapData.draw() over the container that holds both the video and the canvas, and you can pass a bytearray encoded as PNG or JPG to a server-side script to save it.
I can't speak to Silverlight as I've never used it - but a Flex dev could build a basic sample of this for you in Flex in about 20 mins just as a proof of concept.
Where does your expertise lie?
Silverlight you could knock up a proof of concept rather easily and as Myk points out you could do the same in Flex. So your best bet is really whichever technology your current expertise lies in.
In Silverlight you could use a InkPresenter control above a MediaElement control in about 2 minutes up and running with a video file.
I think the hard part is finding a way to display realtime video from your specific device.
Silverlight supports streaming video so having that device talk with Windows Media Server or Silverlight Streaming sounds like the best bet.
Julie Lerman wrote an Silverlight app that you can draw on Images:
http://thedatafarm.com/blog/tablet/drawing-in-silverlight-article-in-msdn-magazine/
the article was presented at a magazine:
http://msdn.microsoft.com/en-us/magazine/cc721604.aspx
Hopes this helps.
I'm planning to make an animation with Silverlight, i want to export the animation to a video format, to be able to share it on video sharing website.
How can i do this ?
You could use a tool like Camtasia to record your screen or part of your screen. It then can be exported to a bunch of different video formats.
A pure code approach is to write a sequence of images, and then combine those images together as a video file. Eric Gunnerson has code to capture images from an animation , its WPF but would probably work in Silverlight? Codeproject has an example of converting a stream of images to an AVI video file in C#. It creates an AVI output. It would be great to go straight to mpg, but as it's compressed the input needs to be a video stream. If you do need mpg as the final output look for an off the shelf avi->mpg converter.
BTW - Let me know how you get on, I'm interested in the performance/functionality of this solution.
MrTelly: That approach would not work because Silverlight does not expose the RenderTargetBitmap class. (Well, this is not completely true, the class is there, but its constructor and methods are all marked SecurityCritical and as such are not normally accessible.)
The Camtasia solution proposed by Jakers is likely the simplest solution.
It's nuts that there isn't a simple way to do this in Silverlight, it's easy as pie in flash.
We have a Silverlight application that needs to load a number of .png files. We can load the images OK, but Silverlight doesn't support reading the pixel data from the Image class.
Can anyone suggest a simple solution for getting at this data? Our current best bet would be a third party .png loading library, but we are having trouble finding a suitable one.
There is no built in classes for doing pixel based imagine manipulation/generation i n Silverlight. You need to implement your own PNG Encoder/Decoder that works on an byte array containing the image information. Joe Stegman has implemented one such encoder you should check out. He got lots of great information about "editable images" in Silverlight over at http://blogs.msdn.com/jstegman/. He does things like applying filters to images, generating mandlebrots and more.
This blog discuss a JPEG Silverilght Encoder (FJCore) you can use to resize and recompress photos client size: http://fluxcapacity.net/2008/07/14/fjcore-to-the-rescue/
Another tool is "Fluxify" which lets you resize and upload photos using Silverilght 2. Can be found over at http://fluxtools.net/
So yes, client side image processing can definitely be done in Silverilght 2. Happy hacking!
PNG decoding is hard to find.
I wrote an article for MSDN that includes some open source code I cobbled together from Joe Stegman, FluxCapacity, and a few others. It includes PNG decoding (as well as GIF, JPG, and BMP) for those in this thread that are looking for that.
http://www.microsoft.com/youshapeit/msdn/ExpertKnowledge/2008-10/InnovateWithSilverlight2.aspx
If you don't care for my implementation of it for Silverlight, then you can go straight to what I modified for PNG decoding: http://sourceforge.net/projects/pr2/
Cheers!
Update: It looks like they no longer offer the source code on the site, so I re-posted the content here:
http://dimebrain.com/2009/01/innovate-with-silverlight-2-article-code-available.html
Thanks - I've seen the Joe Stegman blog. It's very handy, but the decoder he doesn't have is a PNG one. We're using PNGs as we need transparency. The fluxtools link seems to be broken too.
I'm still looking (unsuccessfully) for a PNG decoder I can drop into Silverlight.
One option that may (depending on circumstances) be easier is to save the color data and transparency data separately, then programmatically apply the transparency to the image once you have it loaded. That way, you could save the image as a 8-bit gif representing the alpha channel, plus a jpg or bmp or whatever for the color data.
Dimebrain - that msdn link you provided doesn't have a valid link to the sourcecode - any chance you have a link to the source that works?