Vehicle Camera Systems

Remit

Proposal

Raycomm proposed a solution that included:

• The writing of the USB driver to allow the downloading of the encrypted video data from the camera to a PC
• The writing of a Windows application to allow the downloading and playing back of video clips on the PC. In addition the software would support the secure uploading of the clips to a website and database.
• The development of a website that:
  • Supported the secure uploading and storage of video clips.
  • Provided controlled access to the clips for the owner and his designated insurers.
  • Allowed users to view their video clips by streaming video to their desktop.
  • Allowed the on line selling of the Cameras via an online shop.
  • Updated their current website with a new layout and design.

Special Requirements

The main requirement of the upload and playback software was that the video clips could be downloaded to a PC and uploaded to the website in such away that they could not be tampered with. This required that the video clips should be encrypted throughout their time on the users PC.

Due to the technology employed in the initial camera design the video files were excessively large for 30 second clips. This required that the video files once on the PC should be transcoded to a more manageable size whilst keeping the video quality as high as possible. This was further complicated by the need to be able to stream the video and also play back the video on the PC, both tasks have differing requirements for the required bit rate. By compressing the video, uploads to the website would be faster thus reducing any problems associated with timeouts and other internet communication issues.

Technology

The USB requirements of this project were to download the video files quickly and securely. In order to guarantee the security it was decided not to implement a USB Mass storage driver as is typical in most digital cameras but instead to develop a custom interface that would only support the camera. Its sole purpose was to provide means of securely extracting the video files. The driver would be a typical Windows driver supporting a number of custom USB commands.

The Upload Utility was developed as a managed code application using C# 2.0. This utility includes a video compression engine to compress the encrypted video file. The Windows media services are used to compress the video using a custom profile. Playback of the video on the PC is achieved using the Windows DirectShow multimedia framework this was chosen over spawning a copy of media player as it meant the video could remain encrypted and did not need to be made available as an unencrypted wmv file. In addition the utility provides an upload facility with a secure login that allows the application to be uploaded via a web service.

The website was developed using ASP.NET 2.0 making use of the new membership, roles and user profile providers. This feature allows ASP.NET authentication to be integrated with role management to provide authorisation services for the website. In addition each user can have an associated profile which can provide application-specific customisation that can be tailored by individual users.

The web service provides a secure upload service for the upload of videos. Access to the facility is controlled at login.

Implementation

Driver

Raycomm did not have access to the firmware in the camera. As the USB code implemented was unverified it was decided to make use of a pre-built kernel mode driver and then use a customised user mode access DLL. By adopting this approach it was much easier to track down and debug errors in the USB communications which would inevitably occur if using two untried USB drivers (one in the camera and one on the PC). The result was that problems with the USB interface were quickly tracked back to the USB firmware and corrected allowing our developers to concentrate on the Upload Utility and website. If Raycomm had written the USB code for the camera we would normally have developed our own custom driver. By adopting this approach the source of any USB problems could easily be identified.

This approach allowed easy integration with managed code allowing the PC software to be developed as a managed application in C# 2.0.

Upload Utility

The upload utility is a simple managed C# application. Encryption of file streams is managed using the Crypto library in the .NET framework.

Video play back is provided using the DirectShow.NET library from http://sourceforge.net/projects/directshownet/ which provides .NET interface to the Direct Show api. The video compression uses the WMF SDK via Interop to access the necessary Windows codec to compress the video.

Microsoft Web services 3.0 were used to implement the web services interface for uploading video files.

Web Service

Designed to be used over a secure HTTP connection the MTOM based upload web service allows the secure uploading of the downloaded video clips along with supporting information such as insurer details, incident details etc. The uploading is only possible from the Upload Utility to add some extra protection.

Website

The website is based around an ASP.NET Master Page approach which provides the menus and peripheral graphics images for each page. The content holder for each page is then populated with the individual page contents. CSS Friendly adaptors are used to allow cascading style sheets to be used for formatting.

There are 3 secure areas on the site for

• Users - allows the management of orders , the viewing and management of video clips and updating of user profile details
• Insurers - allows the viewing of users clips if the user has permitted the insurer to do so.
• Site administration - allows for the management of orders and shop facilities, management of users, management of insurer accounts and general site admin.

In addition to the basic website elements and the areas accessible to a logged in user, the site uses Windows Media Server to stream video clips that are selected by the user. Access to the clips is controlled using the membership and role providers. Publishing points are dynamically created for the duration of the playback allowing the user to play back only the video they have selected and have permission to view.

The final element of the website is a simple shop consisting of a list of products with description and prices. It includes some simple stock control features allowing the Site Administrator to see the current stock level as orders are placed. Visual feedback is provided to the shop user by means of a coloured indicator indicating stock, low stock or out of stock products. The site administrators have a simple CMS system for entering products and updating details and price as required.

Raycomm are a UK based, custom software and electronics design and development service company creating bespoke electronic products, mobile device software applications, backend web server software and e-commerce database software.