Filter SDK/Cplusplus API/VideoInfo

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The VideoInfo structure holds global information about a clip (i.e. information that does not depend on the frame number). The GetVideoInfo method in IClip returns this structure. Below is a description of it (for AVISYNTH_INTERFACE_VERSION=5).

Properies and constants

// General properties: 

int width, height;                       // width=0 means no video
unsigned fps_numerator, fps_denominator;
int num_frames;                          // max. num_frames = 2,147,483,647 (signed int32)
int audio_samples_per_second;            // audio_samples_per_second=0 means no audio
int sample_type;                         // samples types are defined in avisynth.h
__int64 num_audio_samples;
int nchannels;

// Colorspace properties and constants: 

int pixel_type; 

enum {
  CS_BGR               = 1<<28,
  CS_YUV               = 1<<29,
  CS_INTERLEAVED       = 1<<30,
  CS_PLANAR            = 1<<31,
  
  // added in v5
  CS_Shift_Sub_Width   =  0,
  CS_Shift_Sub_Height  =  8,
  CS_Shift_Sample_Bits = 16,
  
  CS_Sub_Width_Mask    = 7 << CS_Shift_Sub_Width,
  CS_Sub_Width_1       = 3 << CS_Shift_Sub_Width, // YV24
  CS_Sub_Width_2       = 0 << CS_Shift_Sub_Width, // YV12, I420, YV16
  CS_Sub_Width_4       = 1 << CS_Shift_Sub_Width, // YUV9, YV411
  
  CS_VPlaneFirst       = 1 << 3, // YV12, YV16, YV24, YV411, YUV9
  CS_UPlaneFirst       = 1 << 4, // I420
  
  CS_Sub_Height_Mask   = 7 << CS_Shift_Sub_Height,
  CS_Sub_Height_1      = 3 << CS_Shift_Sub_Height, // YV16, YV24, YV411
  CS_Sub_Height_2      = 0 << CS_Shift_Sub_Height, // YV12, I420
  CS_Sub_Height_4      = 1 << CS_Shift_Sub_Height, // YUV9
  
  CS_Sample_Bits_Mask  = 7 << CS_Shift_Sample_Bits,
  CS_Sample_Bits_8     = 0 << CS_Shift_Sample_Bits,
  CS_Sample_Bits_16    = 1 << CS_Shift_Sample_Bits,
  CS_Sample_Bits_32    = 2 << CS_Shift_Sample_Bits,
  
  CS_PLANAR_MASK       = CS_PLANAR | CS_INTERLEAVED | CS_YUV | CS_BGR | CS_Sample_Bits_Mask | CS_Sub_Height_Mask | CS_Sub_Width_Mask,
  CS_PLANAR_FILTER     = ~( CS_VPlaneFirst | CS_UPlaneFirst ),
};

// Colorformat constants: 

enum {
  CS_UNKNOWN = 0,
  CS_BGR24 = 1<<0 | CS_BGR | CS_INTERLEAVED,
  CS_BGR32 = 1<<1 | CS_BGR | CS_INTERLEAVED,
  CS_YUY2  = 1<<2 | CS_YUV | CS_INTERLEAVED,
  CS_YV12  = 1<<3 | CS_YUV | CS_PLANAR,  // y-v-u, 4:2:0 planar // only in v3
  CS_I420  = 1<<4 | CS_YUV | CS_PLANAR,  // y-u-v, 4:2:0 planar // only in v3
  CS_IYUV  = 1<<4 | CS_YUV | CS_PLANAR,  // same as above // only in v3
  
  // added in v5
  CS_RAW32 = 1<<5 | CS_INTERLEAVED,
  CS_YV24  = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_VPlaneFirst | CS_Sub_Height_1 | CS_Sub_Width_1,  // YUV 4:4:4 planar
  CS_YV16  = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_VPlaneFirst | CS_Sub_Height_1 | CS_Sub_Width_2,  // YUV 4:2:2 planar
  CS_YV12  = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_VPlaneFirst | CS_Sub_Height_2 | CS_Sub_Width_2,  // y-v-u, 4:2:0 planar
  CS_I420  = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_UPlaneFirst | CS_Sub_Height_2 | CS_Sub_Width_2,  // y-u-v, 4:2:0 planar
  CS_IYUV  = CS_I420,
  CS_YUV9  = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_VPlaneFirst | CS_Sub_Height_4 | CS_Sub_Width_4,  // YUV 4:1:0 planar
  CS_YV411 = CS_PLANAR | CS_YUV | CS_Sample_Bits_8 | CS_VPlaneFirst | CS_Sub_Height_1 | CS_Sub_Width_4,  // YUV 4:1:1 planar
  
  CS_Y8    = CS_PLANAR | CS_INTERLEAVED | CS_YUV | CS_Sample_Bits_8,                                     // Y   4:0:0 planar
};

// Image_type properties and constants: 

int image_type;

enum {
  IT_BFF        = 1<<0,
  IT_TFF        = 1<<1,
  IT_FIELDBASED = 1<<2
};

// Chroma placement constants (bits 20 -> 23): 

enum { // added in v5
  CS_UNKNOWN_CHROMA_PLACEMENT = 0 << 20,
  CS_MPEG1_CHROMA_PLACEMENT   = 1 << 20,
  CS_MPEG2_CHROMA_PLACEMENT   = 2 << 20,
  CS_YUY2_CHROMA_PLACEMENT    = 3 << 20,
  CS_TOPLEFT_CHROMA_PLACEMENT = 4 << 20
};

Functions [need to add examples] 

bool HasVideo() const;

This will return true if there is any video in the given clip. 

bool HasAudio() const;

This will return true if there is any audio in the given clip. 

bool IsRGB() const;
bool IsRGB24() const;
bool IsRGB32() const;

All of them will return true if the colorspace is RGB (in any way). The last two return true if the clip has the specific RGB colorspace (RGB24 and RGB32). 

bool IsYUV() const;
bool IsYUY2() const;
bool IsYV24() const;   // v5
bool IsYV16() const;   // v5
bool IsYV12() const;
bool IsYV411() const;  // v5
bool IsY8() const;     // v5

All of them will return true if the colorspace is YUV (in any way). The last six return true if the clip has the specific YUV colorspace (YUY2, YV24, YV16, YV12, YV411 and Y8). 

bool IsColorSpace(int c_space) const;

This will return true if the colorspace (VideoInfo.pixel_type) is the same as the given c_space (or more general it checks for a Colorspace property). 

bool Is(int property) const;

This function is reserved for future use. It currently works the same as IsColorSpace. 

bool IsPlanar() const;

This will return true if the video is planar. See the Planar image format. 

bool IsFieldBased() const;

This will return true if the video is field-based. Thus if has been through a SeparateFields or AssumeFieldBased. Otherwise it will return false. 

bool IsParityKnown() const;

This will return true if the video parity is known (thus if it is TFF or BFF). 

bool IsBFF() const;
bool IsTFF() const;

This will return true if the video is bottom-field-first or top-field-first respectively. 

bool IsVPlaneFirst() const;  // Don't use this

This will return true if the V plane comes first. 

int BytesFromPixels(int pixels) const;

For interleaved formats it will return the number of bytes from the specified number of pixels. For planar formats it will do the same except it operates on the first plane. 

int RowSize(int plane=0) const;

For interleaved formats it will return the width of the frame in bytes. For planar formats it will return the width of the specified plane in bytes.

examples:

640x480 RGB24: RowSize() = 3*640 = 1920

640x480 YV12: RowSize() = 640
640x480 YV12: RowSize(1) = 320 

int BMPSize() const;

For interleaved formats it will return the size of the frame in bytes where the width is rounded up to a multiple of 4 bytes. For planar formats it will do the same but only for the first plane. So, it's the number of bytes of a frame as it was a BMP frame.

examples:

640x480 RGB24: BMPSize() = 480 * 3*640 = 921600
643x480 RGB24: BMPSize() = 480 * 3*644 = 927360

640x480 YV24: BMPSize() = 480 * 640 = 307200
643x480 YV24: BMPSize() = 480 * 644 = 309120

Since v5 the behavior for planar formats is the same as for interleaved formats. 

int GetPlaneWidthSubsampling(int plane) const; // v5

This will return the subsampling of the width in bitshifts.

examples:

YV24: GetPlaneWidthSubsampling(PLANAR_U) = 0 // since there is no horizontal subsampling on a chroma plane
YV16: GetPlaneWidthSubsampling(PLANAR_U) = 0 // since there is no horizontal subsampling on a chroma plane 

int GetPlaneHeightSubsampling(int plane) const; // v5

This will return the subsampling of the height in bitshifts.

examples:

YV24: GetPlaneHeightSubsampling(PLANAR_U) = 0 // since there is no vertical subsampling on a chroma plane
YV16: GetPlaneHeightSubsampling(PLANAR_U) = 1 // since vertically there are two times less samples on a chroma plane compared to a plane which is not subsampled

color format GetPlaneWidthSubsampling(PLANAR_U) GetPlaneHeightSubsampling(PLANAR_U)
YV24 0 0
YV16 1 0
YV12 1 1
YV411 2 1
Y8 0 ? 0 ? 
__int64 AudioSamplesFromFrames(int frames) const;

This returns the number of audiosamples from the first frames frames. 

int FramesFromAudioSamples(__int64 samples) const;

This returns the number of frames from the first samples audiosamples. 

__int64 AudioSamplesFromBytes(__int64 bytes) const;

This returns the number of audiosamples from the specified number of bytes. 

__int64 BytesFromAudioSamples(__int64 samples) const;

This returns the number of bytes from the first samples audiosamples. 

int AudioChannels() const;

This will return the number of audio channels. 

int SampleType() const;

This will return the sample type. See constants for the available sample types. 

bool IsSampleType(int testtype) const;

This will true if the sampletype (VideoInfo.sample_type) is the same as testtype. 

int SamplesPerSecond() const;

This will return the number of bytes per second. 

int BytesPerAudioSample() const;

This will return the number of bytes per sample: 

void SetFieldBased(bool isfieldbased);

This will set the field-based property to true (respectively false) if IsFieldBased()=true (respectively false). 

void Set(int property);
void Clear(int property);

This sets respectively clears an image_type property like: IT_BFF, IT_TFF or IT_FIELDBASED. See field.h for examples. 

int BitsPerPixel() const;

This will return the number of bits per pixel. This can be:

pixel_type nr of bits
CS_BGR32 32
CS_BGR24, CS_YV24 24
CS_YUY2, CS_YV16 16
CS_YV12, CS_I420 12
CS_Y8 8
CS_YV411 6 
int BytesPerChannelSample() const;

This will return the number of bytes per channel-sample. This can be:

sample nr of bytes
SAMPLE_INT8 sizeof(signed char)
SAMPLE_INT16 sizeof(signed short)
SAMPLE_INT24 3
SAMPLE_INT32 sizeof(signed int)
SAMPLE_FLOAT sizeof(SFLOAT) 
void SetFPS(unsigned numerator, unsigned denominator);

This will set the framerate. 

void MulDivFPS(unsigned multiplier, unsigned divisor);

This will multiply the denominator by multiplier and scale the numerator and modified denominator. 

// Test for same colorspace
bool IsSameColorspace(const VideoInfo& vi) const;

This will return true if vi has the same colorformat.

Retrieved from "http://avisynth.nl/index.php?title=Filter_SDK/Cplusplus_API/VideoInfo&oldid=2168"
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