## gsttag gsttag — additional tag definitions for plugins and applications |

## Synopsis

    #include <gst/tag/tag.h>

    #define             GST_TAG_MUSICBRAINZ_TRACKID
    #define             GST_TAG_MUSICBRAINZ_ARTISTID
    #define             GST_TAG_MUSICBRAINZ_ALBUMID
    #define             GST_TAG_MUSICBRAINZ_ALBUMARTISTID
    #define             GST_TAG_MUSICBRAINZ_TRMID
    #define             GST_TAG_CDDA_CDDB_DISCID
    #define             GST_TAG_CDDA_CDDB_DISCID_FULL
    #define             GST_TAG_CDDA_MUSICBRAINZ_DISCID
    #define             GST_TAG_CDDA_MUSICBRAINZ_DISCID_FULL
    #define             GST_TAG_CMML_CLIP
    #define             GST_TAG_CMML_HEAD
    #define             GST_TAG_CMML_STREAM
    #define             GST_TAG_CAPTURING_SHUTTER_SPEED
    #define             GST_TAG_CAPTURING_FOCAL_RATIO
    #define             GST_TAG_CAPTURING_FOCAL_LENGTH
    #define             GST_TAG_CAPTURING_DIGITAL_ZOOM_RATIO
    #define             GST_TAG_CAPTURING_ISO_SPEED
    #define             GST_TAG_CAPTURING_EXPOSURE_PROGRAM
    #define             GST_TAG_CAPTURING_EXPOSURE_MODE
    #define             GST_TAG_CAPTURING_SCENE_CAPTURE_TYPE
    #define             GST_TAG_CAPTURING_GAIN_ADJUSTMENT
    #define             GST_TAG_CAPTURING_WHITE_BALANCE
    #define             GST_TAG_CAPTURING_CONTRAST
    #define             GST_TAG_CAPTURING_SATURATION
    #define             GST_TAG_CAPTURING_SHARPNESS
    #define             GST_TAG_CAPTURING_FLASH_FIRED
    #define             GST_TAG_CAPTURING_FLASH_MODE
    #define             GST_TAG_CAPTURING_METERING_MODE
    #define             GST_TAG_CAPTURING_SOURCE
    #define             GST_TAG_CAPTURING_EXPOSURE_COMPENSATION
    #define             GST_TAG_IMAGE_HORIZONTAL_PPI
    #define             GST_TAG_IMAGE_VERTICAL_PPI
    #define             GST_TAG_ID3V2_HEADER_SIZE
    void                gst_tag_register_musicbrainz_tags   (void);
    gchar *             gst_tag_freeform_string_to_utf8     (const gchar *data,
                                                             gint size,
                                                             const gchar **env_vars);
    gboolean            gst_tag_parse_extended_comment      (const gchar *ext_comment,
                                                             gchar **key,
                                                             gchar **lang,
                                                             gchar **value,
                                                             gboolean fail_if_no_key);
    enum                GstTagImageType;

## Description

Contains additional standardized GStreamer tag definitions for plugins and applications, and functions to register them with the GStreamer tag system.

## Details

### GST_TAG_MUSICBRAINZ_TRACKID

    #define GST_TAG_MUSICBRAINZ_TRACKID "musicbrainz-trackid"

MusicBrainz track ID

### GST_TAG_MUSICBRAINZ_ARTISTID

    #define GST_TAG_MUSICBRAINZ_ARTISTID "musicbrainz-artistid"

MusicBrainz artist ID

### GST_TAG_MUSICBRAINZ_ALBUMID

    #define GST_TAG_MUSICBRAINZ_ALBUMID "musicbrainz-albumid"

MusicBrainz album ID

### GST_TAG_MUSICBRAINZ_ALBUMARTISTID

    #define GST_TAG_MUSICBRAINZ_ALBUMARTISTID "musicbrainz-albumartistid"

MusicBrainz album artist ID

### GST_TAG_MUSICBRAINZ_TRMID

    #define GST_TAG_MUSICBRAINZ_TRMID "musicbrainz-trmid"

MusicBrainz track TRM ID

### GST_TAG_CDDA_CDDB_DISCID

    #define GST_TAG_CDDA_CDDB_DISCID              "discid"

CDDB disc id in its short form (e.g. 'aa063d0f')

### GST_TAG_CDDA_CDDB_DISCID_FULL

    #define GST_TAG_CDDA_CDDB_DISCID_FULL         "discid-full"

CDDB disc id including all details

### GST_TAG_CDDA_MUSICBRAINZ_DISCID

    #define GST_TAG_CDDA_MUSICBRAINZ_DISCID       "musicbrainz-discid"

Musicbrainz disc id (e.g. 'ahg7JUcfR3vCYBphSDIogOOWrr0-')

### GST_TAG_CDDA_MUSICBRAINZ_DISCID_FULL

    #define GST_TAG_CDDA_MUSICBRAINZ_DISCID_FULL  "musicbrainz-discid-full"

Musicbrainz disc id details

### GST_TAG_CMML_CLIP

    #define GST_TAG_CMML_CLIP "cmml-clip"

Annodex CMML clip element tag

### GST_TAG_CMML_HEAD

    #define GST_TAG_CMML_HEAD "cmml-head"

Annodex CMML head element tag

### GST_TAG_CMML_STREAM

    #define GST_TAG_CMML_STREAM "cmml-stream"

Annodex CMML stream element tag

### GST_TAG_CAPTURING_SHUTTER_SPEED

    #define GST_TAG_CAPTURING_SHUTTER_SPEED        "capturing-shutter-speed"

Shutter speed used when capturing an image, in seconds. (fraction)

### GST_TAG_CAPTURING_FOCAL_RATIO

    #define GST_TAG_CAPTURING_FOCAL_RATIO          "capturing-focal-ratio"

Focal ratio (f-number) used when capturing an image. (double)

The value stored is the denominator of the focal ratio (f-number). For example, if this tag value is 2, the focal ratio is f/2.

### GST_TAG_CAPTURING_FOCAL_LENGTH

    #define GST_TAG_CAPTURING_FOCAL_LENGTH         "capturing-focal-length"

Focal length used when capturing an image, in mm. (double)

### GST_TAG_CAPTURING_DIGITAL_ZOOM_RATIO

    #define GST_TAG_CAPTURING_DIGITAL_ZOOM_RATIO   "capturing-digital-zoom-ratio"

Digital zoom ratio used when capturing an image. (double)

### GST_TAG_CAPTURING_ISO_SPEED

    #define GST_TAG_CAPTURING_ISO_SPEED           "capturing-iso-speed"

ISO speed used when capturing an image. (integer)

### GST_TAG_CAPTURING_EXPOSURE_PROGRAM

    #define GST_TAG_CAPTURING_EXPOSURE_PROGRAM     "capturing-exposure-program"

Type of exposure control used when capturing an image. (string)

The allowed values are: "undefined" "manual" "normal" - automatically controlled "aperture-priority" - user selects aperture value "shutter-priority" - user selects shutter speed "creative" - biased towards depth of field "action" - biased towards fast shutter speed "portrait" - closeup, leaving background out of focus "landscape" - landscape photos, background in focus

### GST_TAG_CAPTURING_EXPOSURE_MODE

    #define GST_TAG_CAPTURING_EXPOSURE_MODE       "capturing-exposure-mode"

Exposure mode used when capturing an image. (string)

The allowed values are: "auto-exposure" "manual-exposure" "auto-bracket"

### GST_TAG_CAPTURING_SCENE_CAPTURE_TYPE

    #define GST_TAG_CAPTURING_SCENE_CAPTURE_TYPE  "capturing-scene-capture-type"

Scene mode used when capturing an image. (string)

The allowed values are: "standard" "landscape" "portrait" "night-scene"

### GST_TAG_CAPTURING_GAIN_ADJUSTMENT

    #define GST_TAG_CAPTURING_GAIN_ADJUSTMENT     "capturing-gain-adjustment"

Gain adjustment applied to an image. (string)

The allowed values are: "none" "low-gain-up" "high-gain-up" "low-gain-down" "high-gain-down"

### GST_TAG_CAPTURING_WHITE_BALANCE

    #define GST_TAG_CAPTURING_WHITE_BALANCE       "capturing-white-balance"

White balance mode used when capturing an image. (string)

The allowed values are: "auto" "manual" "daylight" "cloudy" "tungsten" "fluorescent" "fluorescent h" (newer daylight-calibrated fluorescents) "flash"

### GST_TAG_CAPTURING_CONTRAST

    #define GST_TAG_CAPTURING_CONTRAST            "capturing-contrast"

Direction of contrast processing applied when capturing an image. (string)

The allowed values are: "normal" "soft" "hard"

### GST_TAG_CAPTURING_SATURATION

    #define GST_TAG_CAPTURING_SATURATION          "capturing-saturation"

Direction of saturation processing applied when capturing an image. (string)

The allowed values are: "normal" "low-saturation" "high-saturation"

### GST_TAG_CAPTURING_SHARPNESS

    #define GST_TAG_CAPTURING_SHARPNESS          "capturing-sharpness"

Direction of sharpness processing applied when capturing an image. (string)

The allowed values are: "normal" "soft" "hard"

### GST_TAG_CAPTURING_FLASH_FIRED

    #define GST_TAG_CAPTURING_FLASH_FIRED         "capturing-flash-fired"

If flash was fired during the capture of an image. (boolean)

Note that if this tag isn't present, it should not be assumed that the flash did not fire. It should be treated as unknown.

### GST_TAG_CAPTURING_FLASH_MODE

    #define GST_TAG_CAPTURING_FLASH_MODE         "capturing-flash-mode"

The flash mode selected during the capture of an image. (string)

The allowed values are: "auto" "always" "never"

### GST_TAG_CAPTURING_METERING_MODE

    #define GST_TAG_CAPTURING_METERING_MODE      "capturing-metering-mode"

Defines the way a camera determines the exposure. (string)

The allowed values are: "unknown" "average" "center-weighted-average" "spot" "multi-spot" "pattern" "partial" "other"

### GST_TAG_CAPTURING_SOURCE

    #define GST_TAG_CAPTURING_SOURCE             "capturing-source"

Indicates the source of capture. The device/medium used to do the capture. (string)

Allowed values are: "dsc" (= digital still camera) "transparent-scanner" "reflex-scanner" "other"

### GST_TAG_CAPTURING_EXPOSURE_COMPENSATION

    #define GST_TAG_CAPTURING_EXPOSURE_COMPENSATION "capturing-exposure-compensation"

Exposure compensation using when capturing an image in EV. (double)

### GST_TAG_IMAGE_HORIZONTAL_PPI

    #define GST_TAG_IMAGE_HORIZONTAL_PPI         "image-horizontal-ppi"

Media (image/video) intended horizontal pixel density in ppi. (double)

### GST_TAG_IMAGE_VERTICAL_PPI

    #define GST_TAG_IMAGE_VERTICAL_PPI           "image-vertical-ppi"

Media (image/video) intended vertical pixel density in ppi. (double)

### GST_TAG_ID3V2_HEADER_SIZE

    #define GST_TAG_ID3V2_HEADER_SIZE            10

ID3V2 header size considered minimum input for some functions such as `gst_tag_list_from_id3v2_tag()` and `gst_tag_get_id3v2_tag_size()` for example.

### gst_tag_register_musicbrainz_tags ()

    void                gst_tag_register_musicbrainz_tags   (void);

Registers additional musicbrainz-specific tags with the GStreamer tag system. Plugins and applications that use these tags should call this function before using them. Can be called multiple times.

### gst_tag_freeform_string_to_utf8 ()

    gchar *             gst_tag_freeform_string_to_utf8     (const gchar *data,
                                                             gint size,
                                                             const gchar **env_vars);

Convenience function to read a string with unknown character encoding. If the string is already in UTF-8 encoding, it will be returned right away. If not it tries to detect byte-order-mark for UTF-16/32 cases and use that. Otherwise, the environment will be searched for a number of environment variables (whose names are specified in the NULL-terminated string array `env_vars`) containing a list of character encodings to try/use. If none are specified, the current locale will be tried. If that also doesn't work, WINDOWS-1252/ISO-8859-1 is assumed (which will almost always succeed).

`data` : | string data
`size` : | length of string data, or -1 if the string is NUL-terminated
`env_vars` : | a NULL-terminated string array of environment variable names, or NULL
Returns : | a newly-allocated string in UTF-8 encoding, or NULL

### gst_tag_parse_extended_comment ()

    gboolean            gst_tag_parse_extended_comment      (const gchar *ext_comment,
                                                             gchar **key,
                                                             gchar **lang,
                                                             gchar **value,
                                                             gboolean fail_if_no_key);

Convenience function to parse a GST_TAG_EXTENDED_COMMENT string and separate it into its components.

If successful, `key`, `lang` and/or `value` will be set to newly allocated strings that you need to free with `g_free()` when done. `key` and `lang` may also be set to NULL by this function if there is no key or no language code in the extended comment string.

`ext_comment` : | an extended comment string, see GST_TAG_EXTENDED_COMMENT
`key` : | return location for the comment description key, or NULL
`lang` : | return location for the comment ISO-639 language code, or NULL
`value` : | return location for the actual comment string, or NULL
`fail_if_no_key` : | whether to fail if strings are not in key=value form
Returns : | TRUE if the string could be parsed, otherwise FALSE

### enum GstTagImageType

    typedef enum {
      GST_TAG_IMAGE_TYPE_NONE = -1,
      GST_TAG_IMAGE_TYPE_UNDEFINED = 0,
      GST_TAG_IMAGE_TYPE_FRONT_COVER,
      GST_TAG_IMAGE_TYPE_BACK_COVER,
      GST_TAG_IMAGE_TYPE_LEAFLET_PAGE,
      GST_TAG_IMAGE_TYPE_MEDIUM,
      GST_TAG_IMAGE_TYPE_LEAD_ARTIST,
      GST_TAG_IMAGE_TYPE_ARTIST,
      GST_TAG_IMAGE_TYPE_CONDUCTOR,
      GST_TAG_IMAGE_TYPE_BAND_ORCHESTRA,
      GST_TAG_IMAGE_TYPE_COMPOSER,
      GST_TAG_IMAGE_TYPE_LYRICIST,
      GST_TAG_IMAGE_TYPE_RECORDING_LOCATION,
      GST_TAG_IMAGE_TYPE_DURING_RECORDING,
      GST_TAG_IMAGE_TYPE_DURING_PERFORMANCE,
      GST_TAG_IMAGE_TYPE_VIDEO_CAPTURE,
      GST_TAG_IMAGE_TYPE_FISH,
      GST_TAG_IMAGE_TYPE_ILLUSTRATION,
      GST_TAG_IMAGE_TYPE_BAND_ARTIST_LOGO,
      GST_TAG_IMAGE_TYPE_PUBLISHER_STUDIO_LOGO
    } GstTagImageType;

Type of image contained in an image tag (specified as "image-type" field in the info structure in the image's GstSample)

`GST_TAG_IMAGE_TYPE_NONE` | No image type. Can be used to tell functions such as `gst_tag_image_data_to_image_sample()` that no image type should be set.
`GST_TAG_IMAGE_TYPE_UNDEFINED` | Undefined/other image type
`GST_TAG_IMAGE_TYPE_FRONT_COVER` | Cover (front)
`GST_TAG_IMAGE_TYPE_BACK_COVER` | Cover (back)
`GST_TAG_IMAGE_TYPE_LEAFLET_PAGE` | Leaflet page
`GST_TAG_IMAGE_TYPE_MEDIUM` | Medium (e.g. label side of CD)
`GST_TAG_IMAGE_TYPE_LEAD_ARTIST` | Lead artist/lead performer/soloist
`GST_TAG_IMAGE_TYPE_ARTIST` | Artist/performer
`GST_TAG_IMAGE_TYPE_CONDUCTOR` | Conductor
`GST_TAG_IMAGE_TYPE_BAND_ORCHESTRA` | Band/orchestra
`GST_TAG_IMAGE_TYPE_COMPOSER` | Composer
`GST_TAG_IMAGE_TYPE_LYRICIST` | Lyricist/text writer
`GST_TAG_IMAGE_TYPE_RECORDING_LOCATION` | Recording location
`GST_TAG_IMAGE_TYPE_DURING_RECORDING` | During recording
`GST_TAG_IMAGE_TYPE_DURING_PERFORMANCE` | During performance
`GST_TAG_IMAGE_TYPE_VIDEO_CAPTURE` | Movie/video screen capture
`GST_TAG_IMAGE_TYPE_FISH` | A fish as funny as the ID3v2 spec
`GST_TAG_IMAGE_TYPE_ILLUSTRATION` | Illustration
`GST_TAG_IMAGE_TYPE_BAND_ARTIST_LOGO` | Band/artist logotype
`GST_TAG_IMAGE_TYPE_PUBLISHER_STUDIO_LOGO` | Publisher/studio logotype

## See Also

GstTagList