Media Samples
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4/8/2010
After raw bytes have been pulled into the graph, either from a local file or capture card or some other source, the bytes must be parsed into meaningful units, called media samples. Sometimes a source filter does the parsing, and sometimes a separate parsing filter performs this task. In DirectShow, a media sample is wrapped in a COM object that implements the IMediaSample2 Interface. In addition to the actual multimedia data, the object contains information including the specific media type and the synchronization times. A media sample object containing video data holds the data for one video frame. For audio, a media sample object holds the data for several audio samples. In either case, when data moves downstream through a graph from one filter to the next, it is in the form of media sample objects.