GstVideoChroma: GStreamer Base Plugins 1.0 Library Reference Manual

## GstVideoChroma GstVideoChroma — Functions and utility object for operating on chroma video planes |

## Functions

GstVideoChromaSite | gst_video_chroma_from_string ()
const gchar * | gst_video_chroma_to_string ()
void | gst_video_chroma_resample ()
void | gst_video_chroma_resample_free ()
void | gst_video_chroma_resample_get_info ()
GstVideoChromaResample * | gst_video_chroma_resample_new ()

## Types and Values

enum | GstVideoChromaSite
enum | GstVideoChromaFlags
enum | GstVideoChromaMethod
| GstVideoChromaResample

## Includes

    #include <gst/video/video-chroma.h>

## Description

The functions `gst_video_chroma_from_string()` and `gst_video_chroma_to_string()` convert between GstVideoChromaSite and string descriptions.

GstVideoChromaResample is a utility object for resampling chroma planes and converting between different chroma sampling sitings.

## Functions

### gst_video_chroma_from_string ()

    GstVideoChromaSite
    gst_video_chroma_from_string (const gchar *s);

Convert `s` to a GstVideoChromaSite

#### Parameters

s | a chromasite string |

#### Returns

a GstVideoChromaSite or `GST_VIDEO_CHROMA_SITE_UNKNOWN` when `s` does not contain a valid chroma description.

### gst_video_chroma_to_string ()

    const gchar *
    gst_video_chroma_to_string (GstVideoChromaSite site);

Converts `site` to its string representation.

#### Parameters

site | a GstVideoChromaSite |

#### Returns

a string describing `site` .

### gst_video_chroma_resample ()

    void
    gst_video_chroma_resample (GstVideoChromaResample *resample,
                               gpointer lines[],
                               gint width);

Perform resampling of `width` chroma pixels in `lines` .

#### Parameters

resample | a GstVideoChromaResample |
lines | pixel lines |
width | the number of pixels on one line |

### gst_video_chroma_resample_free ()

    void
    gst_video_chroma_resample_free (GstVideoChromaResample *resample);

Free `resample`

#### Parameters

resample | a GstVideoChromaResample |

### gst_video_chroma_resample_get_info ()

    void
    gst_video_chroma_resample_get_info (GstVideoChromaResample *resample,
                                        guint *n_lines,
                                        gint *offset);

The resampler must be fed `n_lines` at a time. The first line should be at `offset` .

#### Parameters

resample | a GstVideoChromaResample |
n_lines | the number of input lines |
offset | the first line |

### gst_video_chroma_resample_new ()

    GstVideoChromaResample *
    gst_video_chroma_resample_new (GstVideoChromaMethod method,
                                   GstVideoChromaSite site,
                                   GstVideoChromaFlags flags,
                                   GstVideoFormat format,
                                   gint h_factor,
                                   gint v_factor);

Create a new resampler object for the given parameters. When `h_factor` or `v_factor` is > 0, upsampling will be used, otherwise subsampling is performed.

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#### Parameters

method | a GstVideoChromaMethod |
site | a GstVideoChromaSite |
flags | GstVideoChromaFlags |
format | the GstVideoFormat |
h_factor | horizontal resampling factor |
v_factor | vertical resampling factor |

#### Returns

a new GstVideoChromaResample that should be freed with `gst_video_chroma_resample_free()` after usage.

## Types and Values

### enum GstVideoChromaSite

Various Chroma sitings.

#### Members

GST_VIDEO_CHROMA_SITE_UNKNOWN | unknown cositing |
GST_VIDEO_CHROMA_SITE_NONE | no cositing |
GST_VIDEO_CHROMA_SITE_H_COSITED | chroma is horizontally cosited |
GST_VIDEO_CHROMA_SITE_V_COSITED | chroma is vertically cosited |
GST_VIDEO_CHROMA_SITE_ALT_LINE | choma samples are sited on alternate lines |
GST_VIDEO_CHROMA_SITE_COSITED | chroma samples cosited with luma samples |
GST_VIDEO_CHROMA_SITE_JPEG | jpeg style cositing, also for mpeg1 and mjpeg |
GST_VIDEO_CHROMA_SITE_MPEG2 | mpeg2 style cositing |
GST_VIDEO_CHROMA_SITE_DV | DV style cositing |

### enum GstVideoChromaFlags

Extra flags that influence the result from `gst_video_chroma_resample_new()`.

#### Members

GST_VIDEO_CHROMA_FLAG_NONE | no flags |
GST_VIDEO_CHROMA_FLAG_INTERLACED | the input is interlaced |

### enum GstVideoChromaMethod

Different subsampling and upsampling methods

#### Members

GST_VIDEO_CHROMA_METHOD_NEAREST | Duplicates the chroma samples when upsampling and drops when subsampling |
GST_VIDEO_CHROMA_METHOD_LINEAR | Uses linear interpolation to reconstruct missing chroma and averaging to subsample |

### GstVideoChromaResample

    typedef struct _GstVideoChromaResample GstVideoChromaResample;