![]() ![]() LEAD has created many videos and audio processors, such as the Video Resize Filter, used to resize a video stream. These are usually custom filters used to perform some type of data processing or generate some type of event. They can handle writing the data to disk to create a media file, or they can send the data to some other location, such as over a network. These filters are usually the last filters in the graph. The output is a single stream containing both video and audio data. Input is usually compressed data from an audio/video encoder. Multiplexer This filter is responsible for joining media streams. The input is usually uncompressed audio or video data, and the output is the compressed version of the same data. These filters are used to compress data, audio or video. The input of the renderer is usually uncompressed data coming from the decoder.Īudio/Video Encoder. For example, when playing a media file with both audio and video, a video renderer would handle displaying the video on the screen, and an audio renderer would handle directing the audio data to the sound device. These filters are used to actually render data. For example, the video decoder input might be a compressed video stream such as MPEG2, and the output could be raw video data. Therefore, they are usually connected to the demultiplexer output. They do not demultiplex, so data should be demultiplexed before it is passed to the decoder. These filters handle the actual decoding or decompression. For example, the filter input might be the actual file or network stream, while the output would be separate audio and video streams. It is usually connected to the source filter. This filter is responsible for splitting the media streams. The data can come from a file on disk, a network, or any other method.ĭemulitplexer. It is responsible for reading the input data. This is usually the first filter in the graph. Since the entire concept of rendering, converting, and capturing files in DirectShow is based on filters and filter graphs, it is important to understand the role of each filter. These handle much of the creation, registration, and connection logic for the filter. Developers can add custom effects or other filters at any stage in the graph, then render the results to a file, URL, or camera.ĭirectShow Base Classes, a set of C++ classes provided in the DirectShow SDK, are used to build most filters. Filters can be connected in different ways for different tasks to build a filter graph that lists all necessary filters to perform a specific task. Filters are connected together by input and output pins. Each step, or stage in the processing of the data, is called a filter. DirectShow's most notable competitor is Apple Computer's QuickTime framework.ĭirectShow divides multimedia task processing such as video playback into a set of steps. Most video-related Windows applications, such as Microsoft's Windows Media Player, Winamp, and Windows Movie Maker, use DirectShow to manage multimedia content. ![]() DirectShow development tools and documentation are distributed as part of the Microsoft Platform SDK. Microsoft produced the DirectShow multimedia framework and API, which replaced the Video for Windows technology (VFW), to enable software developers to perform various operations on media files. DirectShow® also contains DirectX plug-ins for audio signal processing, and DirectX Video Acceleration for accelerated video playback. It can render or record media files on-demand by the user or developer. Microsoft DirectShow is an extensible, filter-based framework, based on the Microsoft Windows Component Object Model (COM), that provides a common interface for media across many of Microsoft's programming languages.
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