About Digital Video in DirectShow

Digital video (DV) can be captured from a DV camera, stored in a file on the user's computer, or stored on tape using a video tape recorder (VTR). Thus, the operations that an application might perform on a DV stream include:

  • Capture live video from a DV camera.
  • Transmit DV data from VTR tape to the computer.
  • Transmit DV data from the computer to the VTR.
  • Read DV data from a file.
  • Write DV data to a file.
  • Render the audio and video in a DV stream.

DirectShow provides the following DV filters:

  • MSDV Driver. The MSDV driver controls a DV device, such as a camcorder. The device may have a camera subunit and a VTR subunit; MSDV controls both subunits. The MSDV driver appears to applications as a DirectShow filter.
  • DV Splitter filter. DV frames contain audio and video in the same frame. The DV Splitter filter extracts the audio data and outputs it as one or two audio streams. It outputs the original data as a separate DV video stream.
  • DV Video Decoder filter. Decodes DV video into uncompressed video.
  • DV Video Encoder filter. Encodes uncompressed video to DV-encoded video.
  • DV Muxer. Combines a DV video stream with one or two audio streams, to create a single interleaved DV stream.

The DV Splitter and DV Video Decoder work together. The splitter takes the interleaved stream and outputs separate audio and DV video streams. The decoder converts the DV video to uncompressed video. The following image illustrates this process.

dv splitter and dv decoder

The DV Video Encoder and the DV Muxer reverse the process: The encoder converts uncompressed video to DV video, and the mux combines audio and DV video to create a single interleaved stream, as shown in the following diagram.

dv encoder and dv muxer

Digital Video in DirectShow