Fooling Around

I added two new simple samples for the MediaTools DirectShow filters to demonstrate how to capture M-JPEG video feed, esp. from an IP camera, and write the video frames into sequence of JPEG files. The other sample takes a directory on the input and plays the images back as video. If you are working on certain transformation filter, it is an easy way to make a reference feed and use it for debugging purposes.

The filters behind that empower the sample are described in another post.

RenderHttpMjpegVideoIntoFiles01 sample takes an URL on the input to generate image/jpeg JPEG or multipart/x-mixed-replace M-JPEG stream. For example, it might be http://demo1.stardotcams.com/nph-mjpeg.cgi feed from a demo StarDot Technologies IP camera.

The application will create a new directory to write files into, and will save each new video frame received into new JPEG file.

Z:\MediaTools\Samples\RenderHttpMjpegVideoIntoFiles01\Release>RenderHttpMjpegVideoIntoFiles01.exe http://demo1.stardotcams.com/nph-mjpeg.cgi
URL: http://demo1.stardotcams.com/nph-mjpeg.cgi
Writing to directory: Z:\MediaTools\Samples\RenderHttpMjpegVideoIntoFiles01\Release\2010-05-12 22-07-37
Event: nCode EC_CLOCK_CHANGED 0xD, nParameter1 0x00000000, nParameter2 0x00000000
Event: nCode EC_PAUSED 0xE, nResult 0x00000000, nParameter2 0x00000000
[...]
^C

The application will generate the files and convert media sample time stamps into file time.

The DirectShow graph that implements the operation is the following:

The other sample RenderJpegFiles01 takes a directory path to look for JPEG files, e.g. generated by previous sample, and pushes them into DirectShow graph as a video feed. File times will be converted [back] to media sample times.

Continue Reading »

ProcessSnapshot is a utility to take a snapshot of process call stacks, and the snapshot taken is written into a human friendly text file.

Additionally to this, the utility has been given a capability to create process minidump files, on user request. The minidump files can be used with debugger to analyze the context of the process using feature rich debug environment, esp. Microsoft Visual Studio. To create a minidump for a process, check a corresponding box and press “Take a Dump” button. A file named “<process-image-name> – <date> <time>.dmp” will be created in the directory of the utility executable.

See also:

• Minidump Files (MSDN)
• How to read the small memory dump files that Windows creates for debugging
• Post-Mortem Debugging Your Application with Minidumps and Visual Studio .NET
• How to View Windows Minidump Files

A binary [Win32, x64] and partial Visual C++ .NET 2008 source code are available from SVN.

A small fix for M-JPEG video streams retrieved by HTTP Stream Source Filter:

• Username and password contained in URL are honored for Basic HTTP authentication
• Correctly parsed HTTP response headers with quotes, e.g.:
  Content-Type: multipart/x-mixed-replace; boundary=“myboundary“

Partial Visual C++ .NET 2008 source code is available from SVN, release binary included.

Unlike video, audio is difficult to troubleshoot in a way that once an issue has been noticed it was dynamic and already in past and it may be difficult to repeat, explain, forward as a screenshot etc. So it needs a visualization in order to check certain specific of the media stream.

Here we go with a Audio Oscillogram Filter, a filter which may be inserted into audio part of the graph, it insists on PCM audio (multichannel is OK, 8 or 16 bits per sample), so decoders might be required upstream and will be automatically inserted.

Once the filter is running, it shows a tool window with a visualization of the waveform coming through. Additionally, it shows a discontinuity sample (that is, a sample with AM_SAMPLE_DATADISCONTINUITY flag)  with a thick read vertical line, and a mismatch (gap or override) in neighboring sample start and stop times with a thin red line.

Additionally to this, a window provides an option to pop up downstream audio renderer property sheet in order to check/debug rendering statistics, such as buffer fullness and break count (programmatically available via IAMAudioRendererStats interface). Unfortunately Microsoft does not provide a well done proxy/stub pair for this interface and the property page and there is no way to access this property page connecting to graph remotely. Using this filter the property sheet is shown directly from the hosting process and works correctly.

A partial Visual C++ .NET 2008 source code is available from SVN, release binary included.

File and Class Summary

Utility.dll

Utility.dll (download) hosts the following classes:

• DirectShow Filters
  • Audio Oscillogram Filter, to visualize/debug audio data

Class Overview

Audio Oscillogram Filter

The filter visualizes PCM audio data going through in a form of oscillogram.

• Filter Executable: Utility.dll
• Filter CLSID: __uuidof(PcmAudioOscillogramFilter) {1450C047-C394-469e-BBB6-A1F949B893FA}
• Filter Property Page CLSID: N/A
• Filter Merit: MERIT_DO_NOT_USE
• Filter Category: CLSID_LegacyAmFilterCategory
• Filter Interfaces: IPersistStreamInit, IPersistStream, IBaseFilter, IMediaFilter, IPersist, IAMovieSetup, IAMFilterMiscFlags, IPcmAudioOscillogramFilter, IDispatch
• Filter Pins: single input pin (Input), single ouput pin (Ouput)
• Input Pin Media Types: MEDIATYPE_Audio/MEDIASUBTYPE_PCM
• Input Pin Interfaces: IPin, IMemInputPin
• Output Pin Media Types: MEDIATYPE_Audio/MEDIASUBTYPE_PCM
• Output Pin Interfaces: IPin

Remarks

The filter will create a tool window with audio visualization when put into paused/running state. The filter graph should be controlled (IMediaControl) from a GUI aware apartment so that window messages could reach internal filter’s window.

Windows Media Codec List utility uses IWMCodecInfo interface (see also IWMCodecInfo2, IWMCodecInfo3) lists installed Windows Media Codecs and their formats and presents the findings in a convenient way. The utility gives a quick idea what a programmer would obtain through IWMCodecInfo2/IWMCodecInfo3 interfaces and what well known format structures (WM_MEDIA_TYPE, AM_MEDIA_TYPE, WAVEFORMATEX, VIDEOINFOHEADER) correspond to particular format.

For a description of Windows Media video and audio codecs, check article Encoding Audio and Video with Windows Media Codecs.

Copy button copies discovered information into clipboard in comma-separated values (CSV) format (e.g. suitable fo rMicrosoft Excel). Submit button posts the same information to this website for… possibly further aggregation.

Some quick facts immediately visualized by the utility:

• for a video codec there is exactly one generic codec format listed
• video codec FOUCCs are: WM Video – WMV1, WMV2, WMV3; WM Video Screen – MSS1, MSS2; WM Video Image – WMVP, WVP2; WM Video Advanced Profile – WVC1
• for audio codecs there are complete codec formats enumerated, with names/descriptions suitable for GUI
• audio codecs enumerate different formats in response to enumeration settings (e.g. request for VBR formats)
• WM Audio Lossless only lists formats for single pass VBR mode
• audio format tags (wFormatTag) are: WM Audio including Professional and Lossless – 0×0161, 0×0162, 0×0163; WM Audio Voice – 0×000A; ACELP.net – 0×0130

Partial Visual C++ .NET 2008 source code is available from SVN, release binary included.

Continue Reading »

Among things beyond of any understanding are those presented by Asustek/Asus engineers. While hardware is more or less OK, software is often confusing. Asus Eee PC 1000HE, out of which I own one, comes with Asus Eee PC Tray Utility 5.1.1.4008.

A helper application to provide quick access to certain hardware control functions, it is OK. No, you don’t have an option to close it and even if you kill it from task manager, another Asus utility will immediately relaunch it. It is a kind monther care from Asus who are just sure that they know the right way.

The laptop las an LCD of 1024×600 pixel reoslution, and, as it usually happens, most accurate, sharp and best looking image is on the display when screen resolution is also set to 1024×600. That is, one virtual screen resolution pixel that matches exactly one physical pixel on the LCD matrix. Do I  need to be so much detailed on the obvious things, because everyone knows this as it seems? Everyone but Asus engineers who for some reasons sell laptops that automatically switch to default resolution 800×600. Even if you change resolution to desired one, the laptop will switch it back  sometimes when you logon, when you reboot, when you use fast switch user capability… Could it be more stupid than that? Perhaps it could, but this way it is already rather annoying.

After less than two months, the hotkey which switches LCD resolution sunk down while it was only used for one thing: to bring back resolution of 1024×600, which beyound of any doubt had to be default resolution without any justification to fall back to a different one for no reason. The key is definitely not going to last for too long.

Out of curiosity, I started the utility on my desktop, where it immediately blinded me by turning off both of my Asus monitors and left me no other way to press reset button to reboot the box.

I thought that there might be an update for the utility on Asus Support website because this kind of thing had to be fixed with apologies and sincere promises to never happen again. I was reluctant to use Asus Update utility because it is more refined masterpiece of stupidity. However on the website, there is no utility in downloads at all. It could be a part of another downloadable package, but there was also no obvious indication that would give a hint what update is required.

So that only solution left was to anatomize the crapware and think of a workaround to at least for some time extend the life of the hotkey. The utility below, PostAsTrayCommand, will look for Asus tray icon utility to be running and will post a requested command (this way it can also be used to switch on or off wireless LAN, or the camera) to the utility.

To switch resolution to 1024×600, a command of 32797 has to be posted. The screenshot below gives an idea of other values, which might be useful:

To post a command, it needs to be started from command line “PostAsTrayCommand.exe 32797″ and it makes sense to add it to Startup group to be automatically launched on logon.

A Visual C++ .NET 2008 source code is available from SVN, release binary included.

Media Tools DirectShow Filters can be used to acquire, parse and decoder M-JPEG encoded video stream from an IP camera or a video server, however for a quick start it is necessary to properly register filters on system and create a DirectShow graph.

To register the filters, it is necessary to download DLLs from repository. While Acquisition.dll does not require special prerequisites installed, CodingI.dll is using Intel Integrated Performance Primitives (IPP) version 6.0.0 internally and requires its [at least] redistributables installed before DLLs are being registered using regsvr32.

Intel went further with new releases of IPP, which are incompatible with the version used to build CodingI.dll, so it is version 6.0.0 (in downloads on Intel website: version 6.0 build 0) has to be installed. Note that Intel DLLs from C:\Program Files\Intel\IPP\6.0.0.044\ia32\bin (version 6.0.0.062 is known to be also compatible) need to be on system search path, or copied to C:\Windows\system32 directory.

Once Intel IPP is prepared, it is required to register CodingI.dll using regsvr32. This registers filters and they are available in GraphEdit and for applications. It is important that on the way of constructing graph which renders video using standard video renderers it is required to specify correct resolution for video, or otherwise graph might fail to start with a message “The graph could not change state”, caused by video renderer failure to dynamically change to different (effective) resolution.

To create rendering graph, add Alax.Info HTTP Stream Source Filter from the filter list and provide camera URL in properties, e.g. http://cam15001.miemasu.net/nphMotionJPEG?Kind=1

Continue Reading »