I am targeting windows machines. I need to get access to the pointer to the byte array describing the individual streaming frames from an attached usb webcam. I saw the playcap directshow sample from the windows sdk, but I dont see how to get to raw data, frankly, I don't understand how the video actually gets to the window. Since I don't really need anything other than the video capture I would prefer not to use opencv.
Visual Studio 2008 c++
Insert the sample grabber filter. Connect the camera source to the sample grabber and then to the null renderer. The sample grabber is a transform, so you need to feed the output somewhere, but if you don't need to render it, the null renderer is a good choice.
You can configure the sample grabber using ISampleGrabber. You can arrange a callback to your app for each frame, giving you either a pointer to the bits themselves, or a pointer to the IMediaSample object which will also give you the metadata.
You need to implement ISampleGrabberCB on your object, and then you need something like this (pseudo code)
IFilterInfoPtr m_pFilterInfo;
ISampleGrabberPtr m_pGrabber;
m_pGrabber = pFilter;
m_pGrabber->SetBufferSamples(false);
m_pGrabber->SetOneShot(false);
// force to 24-bit mode
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(mt));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24;
m_pGrabber->SetMediaType(&mt);
m_pGrabber->SetCallback(this, 0);
// SetCallback increments a refcount on ourselves,
// but we own the grabber so this is recursive
/// -- must addref before SetCallback(NULL)
Release();
Related
I have a EmbeddedMediaPlayerComponent and I want to check before playing if the video has audio track.
The getMediaPlayer().getAudioTrackCount() method works fine but only when I play the video and I am inside the public void playing(MediaPlayer mp) event.
I also tryed
getMediaPlayer().prepareMedia("/path/to/media", null);
getMediaPlayer().play();
System.out.println("TRACKS: "+getMediaPlayer().getAudioTrackCount());
But it does not work. it says 0.
I also tryed:
MediaPlayerFactory factory = new MediaPlayerFactory();
HeadlessMediaPlayer p = factory.newHeadlessMediaPlayer();
p.prepareMedia("/path/to/video", null);
p.parseMedia();
System.out.println("TRACKS: "+p.getAudioTrackCount());
But it also says -1. Is there a way I can do that ? or using another technique?
The track count is not metadata, so using parseMedia() here is not going to help.
parseMedia() will work to get e.g. ID3 tag data, title, artist, album, and so on.
The track data is usually not available until after the media has started playing, since it is the particular decoder plugin that knows how many tracks there are. Even then, it is not always available immediately after the media has started playing, sometimes there's an indeterminate delay (and no LibVLC event).
In applications where I need the track information before playing the media, I usually would use something like the native MediaInfo application and parse the output - this has a plain-text out format, or an XML output format and IIRC the newer versions have a JSON output format. The downside is you have to launch a native process to do this, I use CommonsExec for things like this. It's pretty simple and does work even though it's not a pure Java solution, but neither is vlcj!
A slight aside if you did actually want the meta data there is an easier way, just use
this method on the MediaPlayerFactory:
public MediaMeta getMediaMeta(String mediaPath, boolean parse);
This gives you the meta data without having to prepare, play or parse media.
Is there a way to read the info (fps, bitrate, duration, codecs required, etc.) of a media file (avi, mp4, mkv, etc.) on windows using visual studio c++?
I managed to play various files (which I actually don't even want) using directshow (http://msdn.microsoft.com/en-us/library/windows/desktop/dd389098%28v=vs.85%29.aspx) but I don't know how to only get the information from the file.
Edit: I got it working like this...
int height, width, framerate, bitrate;
LARGE_INTEGER duration;
// initialize the COM library
CoInitialize(NULL);
//
IPropertyStore* store = NULL;
SHGetPropertyStoreFromParsingName(L"E:\\test.avi", NULL, GPS_DEFAULT, __uuidof(IPropertyStore), (void**)&store);
PROPVARIANT variant;
store->GetValue(PKEY_Media_Duration, &variant);
duration = variant.hVal;
store->GetValue(PKEY_Video_FrameHeight, &variant);
height = variant.lVal;
store->GetValue(PKEY_Video_FrameWidth, &variant);
width = variant.lVal;
store->GetValue(PKEY_Video_FrameRate, &variant);
framerate = variant.lVal;
store->GetValue(PKEY_Video_TotalBitrate, &variant);
bitrate = variant.lVal;
//
store->Release();
//
CoUninitialize();
You can obtain this information via DirectShow, however if you don't need the playback/streaming pipeline and you are on Windows 7, then you possibly have a better alternate option to get the data from shell properties - those supplying data to display in additional columns of Windows explorer.
SHGetPropertyStoreFromParsingName gets you property store
MSDN entry point for Shell Metadata Providers
Code snippet: How to use the IPropertyStore to obtain Media_Duration?
Have you considered using the MediaInfo SDK? You can get extensive information about all of the audio and video streams available in the container, including codec specifics, as well as everything you were asking about.
Their getting started guide and reference documentation are here:
http://mediaarea.net/en/MediaInfo/Support/SDK/Quick_Start
http://mediaarea.net/en/MediaInfo/Support/SDK/More_Info
Code is available at their SourceForge page here.
I am porting coding from Objective C to MonoTouch to use an external accessory. It is super basic coding, however when I create The EASession and try to use the InputStream or OutputStream, they are both NULL. I have used it in Objective-C so I know this should not happen.
I am able to repeatedly connect/disconnect the device and detect it. Now I just can't seem to read the data from the device because of this null issue. Below is my coding:
session = new EASession(acc, "com.idtechproducts.reader");
session.OutputStream.Delegate = streamDel; // Crashed saying OutputStream is null
session.OutputStream.Schedule (NSRunLoop.Current , "NSDefaultRunLoopMode");
session.OutputStream.Open ();
You need to list the external accessories you're going to use in your
Info.plist.
There is some documentation on this on apple's site:
http://developer.apple.com/library/ios/#featuredarticles/ExternalAccessoryPT/Introduction/Introduction.html#//apple_ref/doc/uid/TP40009502
Here is a screenshot of how to set this value in Info.plist:
http://screencast.com/t/AYmOWjf8wkL
I was wondering how I can select the output device for audio in directshow. I am able to get available audio output devices in directshow. But how can I make one of these to be audio output device. Its always going for the default audio device. I want to be able to output audio on my choice of device. I have been struggling through google but couldn't find anything useful. All I could get was this link but it doesn't really solve my problem.
Any help will be really helpful for me.
First off, if you're not using DirectShow .NET (DirectShowLib), get that here: It serves as a (very complete) interface between unmanaged DirectShow and C#
What follows is a pretty simple example of how to play an audio file, to the desired audio device
using DirectShowLib;
private IGraphBuilder m_objFilterGraph = null;
private IBasicAudio m_objBasicAudio = null;
private IMediaControl m_objMediaControl = null;
private void playAudioToDevice(string fName, int devIndex)
{
object source = null;
DsDevice[] devices;
devices = DsDevice.GetDevicesOfCat(FilterCategory.AudioRendererCategory);
DsDevice device = (DsDevice)devices[devIndex];
Guid iid = typeof(IBaseFilter).GUID;
device.Mon.BindToObject(null, null, ref iid, out source);
m_objFilterGraph = (IGraphBuilder)new FilterGraph();
m_objFilterGraph.AddFilter((IBaseFilter)source, "Audio Render");
m_objFilterGraph.RenderFile(fName, "");
m_objBasicAudio = m_objFilterGraph as IBasicAudio;
m_objMediaControl = m_objFilterGraph as IMediaControl;
m_objMediaControl.Run();
}
It is up to user to manage audio devices and choose a primary device (such as via Control Panel applet). You can find ways to switch devices programmatically in Windows XP, however in Vista+ it is impossible without interactive user action by design.
See also Larry's answer here: How to change default sound playback device programmatically?
UPDATE: The mentioned above refers to modifying system configuration trying to alter default audio output device. An application is however not limited to default device only. Instead, it can enumerate available devices (see Using the System Device Enumerator + CLSID_AudioRendererCategory) and then create an instance of renderer for specific device with BindToObject call. From there on, it is a regular filter, just bound internally to device of interest.
I have a legacy MCF application that displays some images (bmp 32-bits with alpha channel information) by pre-multiplying the images and using CDC::AlphaBlend method.
I would like to introduce some new graphics using Direct2D but I don't want to migrate all the images to png or other formats.
I managed to draw a bmp image from a file but I'm facing problems to get the image from resources and also the displayed image does not use the alpha channel information.
So could anybody help me out with this?
This is my code to create the bitmap:
hr = pIWICFactory->CreateDecoderFromFilename( L"D:\\image.bmp",
NULL,
GENERIC_READ,
WICDecodeMetadataCacheOnDemand,
&pDecoder);
if (SUCCEEDED(hr))
{
// Create the initial frame.
hr = pDecoder->GetFrame(0, &pSource);
}
if (SUCCEEDED(hr))
{
//create a Direct2D bitmap from the WIC bitmap.
hr = pRenderTarget->CreateBitmapFromWicBitmap(
pSource,
NULL,
ppBitmap
);
}
This is the code to draw the bitmap:
m_pRenderTarget->DrawBitmap(
m_pBitmap,
D2D1::RectF(0.0f, 0.0f, size.width, size.height)
);
You'll need to make an IStream from the resource to pass to IWICImagingFactory::CreateDecoderFromStream.
Since resources are available in memory (assuming the module that contains them is loaded), the easiest way to do that is to create an IWICStream object using IWICImagingFactory::CreateStream and initialize it using IWICStream::InitializeFromMemory.
To get the size of the resource and a pointer to the first byte, use the FindResource, LoadResource, LockResource, and SizeofResource functions.
If your bitmap's header uses BI_BITFIELDS to specify a format with alpha data, I believe WIC will respect that. I don't have any experience with Direct2D, so I can't say if you need to do anything further to make it use alpha data.
If you can't use BI_BITFIELDS (or if that doesn't work), you can write your own IWICBitmapSource implementation that wraps the frame's IWICBitmapSource. You should be able to pass most calls directly to the frame source, and supply your own GetPixelFormat method that returns the real format of your image data. Alternatively, you can create an IWICBitmap with the format you want, lock the bitmap, and copy in the pixel data from the frame source.