## MPEG-1 Media Types

The following information summarizes the media types used by Microsoft® DirectShow™ for MPEG data.

MPEG-1 System Stream
  Major type: MEDIATYPE_Stream

  Minor type: MEDIASUBTYPE_MPEG1System

  Format: None

  Sample contents: BYTE stream; no alignment

MPEG-1 System Stream off Video CD
  Major type: MEDIATYPE_Stream

  Minor type: MEDIASUBTYPE_MPEG1VideoCD

  Format: None

  Sample contents: BYTE stream; no alignment

MPEG-1 Audio Packet
  Major type: MEDIATYPE_Audio

  Minor type: MEDIASUBTYPE_MPEG1Packet

  Format: MPEG1WAVEFORMAT

  Sample contents: Single MPEG-1 packet including packet header

MPEG-1 Audio payload
  Major type: MEDIATYPE_Audio

  Minor type: MEDIASUBTYPE_MPEG1Payload

  Format: MPEG1WAVEFORMAT

  Sample contents: Byte-aligned MPEG-1 audio data

MPEG-1 Video Packet
  Major type: MEDIATYPE_Video

  Minor type: MEDIASUBTYPE_MPEG1Packet

  Format: VIDEOINFO + Video sequence header

  Sample contents: Single MPEG-1 packet including packet header

MPEG-1 Video payload
  Major type: MEDIATYPE_Video

  Minor type: MEDIASUBTYPE_MPEG1Payload

  Format: VIDEOINFO + Video sequence header

  Sample contents: Byte-aligned MPEG-1 video data

MPEG-1 Native Video Stream
  Major type: MEDIATYPE_Stream

  Minor type: MEDIASUBTYPE_ MPEG1Video

  Format: None

  Sample contents: Array of video stream bytes (no system layer)

MPEG-1 Native Audio Stream
  Major type: MEDIATYPE_Stream

  Minor type: MEDIASUBTYPE_ MPEG1Audio

  Format: None

  Sample contents: Array of audio stream bytes (no system layer)

The various filters will support pins as follows:

Filter | Direction | Media type(s)
System layer splitter | Input | MPEG-1 system stream MPEG-1 system stream off Video CD
System layer splitter | Output | MPEG-1 Audio packet or MPEG-1 Audio data
System layer splitter | Output | MPEG-1 Video packet or MPEG-1 Video data
Software Audio CODEC | Input | MPEG-1 Audio data or MPEG-1 Audio packet
Software Video CODEC | Input | MPEG-1 Video data or MPEG-1 Video packet
Software Audio CODEC | Output | PCM audio mono or stereo, input sampling rate, input sampling rate divided by 2 or input sampling rate divided by 4
Software Video CODEC | Output | Uncompressed video in Y41P, YUY2, UYVY, RGB24, RGB32, RGB565, RGB555 and RGB8 formats

MPEG-1 Video packet and payload media types contain a complete sequence header so that data can be played from the middle of a file without needing a sequence header to initialize the video playback.

The video sequence header is appended to the video data type for MPEG video so that play can begin from the middle of a stream. The length of this field is up to 140 bytes (it includes the sequence header start code—0x000001B3—at the start and any quantization matrices found in the first sequence header encountered).

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