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4/8/2010

DirectShow uses the AM_MEDIA_TYPEstructure to describe media samples.

This structure includes GUID fields for major type, subtype, and format type, as well as fields specifying other properties of the sample, such as whether the samples are compressed.

The following sections summarize the major type and subtype options registered by DirectShow. These media types are defined in the header file Uuids.h.

Media Types with No Subtype

The following table describes the media types with no subtype.

Type	Description
MEDIATYPE_AnalogAudio	Analog audio connection.
MEDIATYPE_File	Media type is a file, used closed captions.
MEDIATYPE_Interleaved	Data is interleaved, used by Digital Video (DV).
MEDIATYPE_Midi	Data is MIDI format.
MEDIATYPE_ScriptCommand	Data is a script command, used by closed captions.
MEDIATYPE_Text	Data is text.
MEDIATYPE_Timecode	Data is timecode data.

Audio Media Types

The wFormatTagmember in the WAVEFORMATEXstructure specifies the audio format type.

The format type is generally FORMAT_WaveFormatEx. Media samples are generally whole number of samples as specified in the wBitsPerSamplemember in the WAVEFORMATEXstructure. This is not necessarily true for MPEG audio samples that can come from packetized streams and are therefore not necessarily packaged on sample/frame boundaries.

For MPEG audio the time stamp in a media sample is the time stamp for the first frame whose first byte is contained in the media sample.

Media subtypes are defined for each wFormatTagas follows:

The Data1 subfield of the Media Subtype is the same as the wFormatTagvalue.
The Data 2 field is 0.
The Data 3 field is 0x0010.
The Data 4 field is 0x80, 0x00, 0x00, 0xAA, 0x00, 0x38, 0x9B, 0x71.

Thus, for PCM audio the subtype GUID would be:

	Copy Code
{00000001-0000-0010-8000-00AA00389B71}

Older filters may still use GUID_NULLas the subtype so this should be checked for. However, registration of a filter with the explicit subtype greatly improves the speed of graph loading, especially when the given filter is not required.

The CreateAudioMediaTypefunction can be used to create an AM_MEDIA_TYPEstructure from a WAVEFORMATEXStructure.

The following table describes the audio media subtypes.

MEDIATYPE_Audio	Data is audio
MEDIASUBTYPE_PCMAudio	PCM audio
MEDIASUBTYPE_MPEG1Packet	MPEG1 Audio Packet
MEDIASUBTYPE_MPEG1Payload	MPEG1 Audio Payload

Buffering Media Types

The media types MEDIATYPE_AudioBuffered and MEDIATYPE_VideoBuffered identify that an encoding filter cannot encode data in real time. The Capture Graph Builder inserts a buffering filter immediately upstream from the encoding filter whenever it encounters either of these media types. The MEDIATYPE_AudioBuffered and MEDIATYPE_VideoBuffered media types support the same subtypes as MEDIATYPE_Audio and MEDIATYPE_Video respectively.

Line 21 Media Types

The following table describes the line 21 closed captioning media subtypes.

MEDIATYPE_AUXLine21Data	Data is line 21 type, used by closed captions
MEDIASUBTYPE_Line21_BytePair	Line 21 data as byte pairs
MEDIASUBTYPE_Line21_GOPPacket	Line 21 data in DVD GOP Packet
MEDIASUBTYPE_Line21_VBIRawData	Line 21 data in raw VBI format

MPEG-2 Media Types

The following table describes the MPEG-2 media subtypes.

MEDIATYPE_MPEG2_PES	Data is MPEG-2 format, used by DVD
MEDIASUBTYPE_DVD_SUBPICTURE	Subpicture data
MEDIASUBTYPE_DOLBY_AC3	Dolby data
MEDIASUBTYPE_MPEG2_AUDIO	MPEG-2 audio data
MEDIASUBTYPE_DVD_LPCM_AUDIO	DVD audio data

Stream Media Types

Time stamps are byte positions * 10000000 (notionally 1 byte per second) rather than real times.

The following table describes the stream media subtypes.

MEDIATYPE_Stream	Data is a non-time stamped byte stream
MEDIASUBTYPE_Avi	Data from AVI file
MEDIASUBTYPE_WAVE	Data from WAV file
MEDIASUBTYPE_AU	Data from AU file
MEDIASUBTYPE_AIFF	Data from AIFF file
MEDIASUBTYPE_MPEG1Video	MPEG video
MEDIASUBTYPE_MPEG1System	MPEG system
MEDIASUBTYPE_MPEG1VideoCD	MPEG video CD
MEDIASUBTYPE_MPEG1Audio	MPEG audio
MEDIASUBTYPE_DssVideo	Dss Video
MEDIASUBTYPE_DssAudio	Dss Audio

Video Media Types

The following table describes the video media subtypes.

MEDIATYPE_Video	Data is video
MEDIASUBTYPE_YVU9	Standard YVU9 format uncompressed data. A planar YUV format. A Y sample at every pixel, a U and V sample at every fourth pixel horizontally on each line; a Y sample on every vertical line, a U and V sample at every fourth vertical line. 9 bits per pixel.
MEDIASUBTYPE_Y411	YUV 411 format data. Same as Y41P.
MEDIASUBTYPE_Y41P	Y41P format data. A packed YUV format. A Y sample at every pixel, a U and V sample at every fourth pixel horizontally on each line; every vertical line sampled. Byte ordering (lowest first) is U0, Y0, V0, Y1, U4, Y2, V4, Y3, Y4, Y5, Y6, Y7, where the suffix 0 is the leftmost pixel and increasing numbers are pixels increasing left to right. Each 12-byte block is 8 image pixels.
MEDIASUBTYPE_YUY2	YUY2 format data. Same as UYVY but with different pixel ordering. Byte ordering (lowest first) is Y0, U0, Y1, V0, Y2, U2, Y3, V2, Y4, U4, Y5, V4, where the suffix 0 is the leftmost pixel and increasing numbers are pixels increasing left to right. Each 4-byte block is 2 image pixels.
MEDIASUBTYPE_YVYU	YVYU format data. A packed YUV format. Same as UYVY but with different pixel ordering. Byte ordering (lowest first) is Y0, V0, Y1, U0, Y2, V2, Y3, U2, Y4, V4, Y5, U4, where the suffix 0 is the leftmost pixel and increasing numbers are pixels increasing left to right. Each 4-byte block is 2 image pixels.
MEDIASUBTYPE_UYVY	UYVY format data. A packed YUV format. A Y sample at every pixel, a U and V sample at every second pixel horizontally on each line; every vertical line sampled. Probably the most popular of the various YUV 4:2:2 formats. Byte ordering (lowest first) is U0, Y0, V0, Y1, U2, Y2, V2, Y3, U4, Y4, V4, Y5, where the suffix 0 is the leftmost pixel and increasing numbers are pixels increasing left to right. Each 4-byte block is 2 image pixels.
MEDIASUBTYPE_Y211	YUV 211 format data. A packed YUV format. A Y sample at every second pixel, a U and V sample at every fourth pixel horizontally on each line; every vertical line sampled. Byte ordering (lowest first) is Y0, U0, Y2, V0, Y4, U4, Y6, V4, Y8, U8, Y10, V8, where the suffix 0 is the leftmost pixel and increasing numbers are pixels increasing left to right. Each 4-byte block is 4 image pixels.
MEDIASUBTYPE_CLJR	Cirrus Logic Jr YUV 411 format with less than 8 bits per Y, U, and V sample. A Y sample at every pixel, a U and V sample at every fourth pixel horizontally on each line; every vertical line sampled.
MEDIASUBTYPE_IF09	Indeo produced YVU9 format with additional information about differences from the last frame. 9.5 bits per pixel but reported as 9.
MEDIASUBTYPE_MJPG	Motion JPEG (MJPG) compressed video.
MEDIASUBTYPE_TVMJ	TrueVision MJPG format.
MEDIASUBTYPE_WAKE	MJPG format produced by some cards.
MEDIASUBTYPE_CFCC	MJPG format produced by some cards.
MEDIASUBTYPE_IJPG	JPEG format.
MEDIASUBTYPE_Plum	Plum MJPG format.
MEDIASUBTYPE_RGB1	RGB 1 bit per pixel. Palettized.
MEDIASUBTYPE_RGB4	RGB 4 bits per pixel. Palettized.
MEDIASUBTYPE_RGB8	RGB 8 bits per pixel. Palettized.
MEDIASUBTYPE_RGB565	565 format of RGB, 16 bits per pixel. Uncompressed RGB samples.
MEDIASUBTYPE_RGB555	555 format of RGB, 16 bits per pixel. Uncompressed RGB samples.
MEDIASUBTYPE_RGB24	RGB 24 bits per pixel. Uncompressed RGB samples.
MEDIASUBTYPE_RGB32	RGB 32 bits per pixel. Uncompressed RGB samples.
MEDIASUBTYPE_Overlay	Video delivered using hardware overlay.
MEDIASUBTYPE_dvsd	Standard DV format.
MEDIASUBTYPE_dvhd	High Definition DV format.
MEDIASUBTYPE_dvsl	Long Play DV format.
MEDIASUBTYPE_MPEG1Packet	MPEG1 Video Packet.
MEDIASUBTYPE_MPEG1Payload	MPEG1 Video Payload.
MEDIASUBTYPE_VideoPort	Data is video port data, used with DVD.