These Transform filters are often (somewhat erroneously) called Decoder Filters, or Codecs (which stands for enCODer/DECoder), because they often take care of decompressing the media. This data is usually then passed over to a set of Transform filters which decode the different media streams (including audio, video, and metadata, such as subtitles). The Source Filter (often referred to as the Splitter Filter) reads the file container format and splits out the different "streams" of data contained within. Usually, however, you need one Source Filter, one or more Transform filters, and one or more Render Filters. To play back a file properly via DirectShow you always need at least one Source Filter and one Render filter. A codec is a special type of filter (or other similar software) that can both encode a media stream to a compressed format, and decode a stream from that same compressed format - a COmpressor/DECompressor, which is how it gets its name. So, wrapped up inside the AVI or MP4 file there will be one or more different types of media, usually compressed with a codec of some type. It is the individual media streams inside the container which make up the actual media, including metadata tags, video streams, audio streams, subtitles, and other information. The container format is essentially the file you see on your hard drive (the AVI, MKV, MP4, OGM, or whatever) which is used to identify and interleave the different media stream types. With most media files, there is a distinction between the file container format and the individual media stream types (sometimes referred to as the codec or the FourCC of the file) "contained" inside the file. Generally speaking, there are three types of filters in terms of functionality: Source filters, Transform filters, and Render filters.īefore explaining what these different types of filters do, it is useful to understand a bit more about how multimedia content is stored in files on disk. Filter Types further information: DirectShow Playback Guide: Filter Types The pins are the connections between the different filter boxes, with outputs on one end and inputs on the other. GraphEdit with a x264 compressed MKV file loaded, showing the default filter graph. You can use the free GraphEdit utility from Microsoft to manually build filter graphs if you want to play around with how this works. FFDSHOW will then connect it's input pins to Haali's output pins and decode the video stream. For example, the Input pin of the Haali Media Splitter will receive the data from the file, split it to it's component parts and then output those "streams" via it's output pins. Pins are the means by which media data is passed from one filter to another filter. Filters have âpinsâ - points of connection between filters, both input pins and output pins. Each filter in the Filter Graph chain processes audio/video data in a specific way to facilitate the playing of the media files. They are sort of like little "plugins" for DirectShow that allow it to handle different types of media, different types of files, or perform transformations on the media data. A filter is a software component in DirectShow that will work with other similar components to render a media file. A filter graph is like a chain of individual âDirectShow Filtersâ. DirectShow is a Microsoft technology for playing (and recording) audio/video media on a Windows computer.ĭirectShow uses the concept of âFilter Graphâ to take a multimedia file on disk and turn it into what you see or hear from your computer. Media Center plays many media formats in DirectShow, including DVD and many video and audio files. What is DirectShow? What is a DirectShow filter?
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