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Encoder and Decoder Development

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[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

This section contains articles about encoder and decoder development for DirectShow. These topics are not relevant for application developers.

A software decoder that supports DirectX Video Acceleration (VA) must be implemented as a DirectShow copy transform filter. If the decoder does not support DirectX VA, it can also be implemented as a DirectX Media Object (DMO). A decoder that connects to a video renderer should not be implemented as a trans-in-place filter, because this will result in significant performance degradation. For information on how to write a copy transform filter, see Writing Transform Filters.

Software encoders can be implemented as either transform filters or DMOs. Encoders do not use DirectX VA, since DirectX VA currently is only used for decompression. The Encoder API specification described in this section is relevant for both hardware and software encoders.

This section contains the following topics:

Using the VMR for DirectShow Filter Developers