DirectShow
DirectShow (formerly called ActiveMovie) is an architecture developed by Microsoft specifically for multimedia. DirectShow is currently included with Windows 98, Windows 2000, Windows XP, Windows ME and Internet Explorer.
What Issues Does DirectShow Address?
- Large amounts of data must be processed very quickly.
- The audio, video and any additional streams must all be synchronized to start and stop at the same time and play at the same rate.
- Streams can come from many various sources, including local media files, computer networks, broadcasts, video cameras and other media devices.
- Streams come in a variety of formats, such as Audio-Video Interleaved (AVI), Advanced Streaming Format (ASF), and Motion Picture Experts Group (MPEG).
- An application developer has no way of knowing what hardware devices will be installed on the end-user's system.
How does DirectShow Address The Issues?
To achieve the throughput necessary for streaming video and audio, DirectShow uses DirectDraw® and DirectSound® to render data efficiently to the system's sound and graphics cards. Synchronization is achieved by encapsulating the multimedia data in time-stamped media samples. To handle the variety of sources, formats, and hardware devices, DirectShow uses a modular architecture in which operating system components called filters can be mixed and matched to provide support for many different scenarios.
DirectShow includes filters that support codecs written for the Audio Compression Manager (ACM) and Video Compression Manager (VCM) interfaces.
DirectShow enables applications to play files and streams from various sources, including local files and remote files on a network. DirectShow has native compressors and decompressors for some file formats, and many third-party hardware and software decoders are compatible with DirectShow. In addition, DirectShow supports legacy Video for Windows codecs based on the Video Compression Manager (VCM) and Audio Compression Manager (ACM) interfaces. Playback makes full use of DirectDraw hardware acceleration and DirectSound capabilities when the hardware supports it.
Q: Why use LEADTOOLS Multimedia and not use the DirectShow SDK directly (after all it is free) to save some money?
A: DirectShow is indeed free and powerful, but very complex. Much time will be required to write a robust capture application by calling DirectShow directly. Although, you will save money by not purchasing a toolkit, you will spend much more money on the time required to write the code from scratch to make the application work with various different capture cards. No two capture devices are exactly the same, and it will take time to write the code that will work with every device. With a LEADTOOLS Multimedia product you avoid the complexities of writing an application that calls DirectShow directly.
