gstaudio

## gstaudio gstaudio — Support library for audio elements |

## Synopsis

    #include <gst/audio/audio.h>

    enum                GstAudioFlags;
    enum                GstAudioFormat;
    enum                GstAudioFormatFlags;
    struct              GstAudioFormatInfo;
    struct              GstAudioInfo;
    void                gst_audio_info_init                 (GstAudioInfo *info);
    gboolean            gst_audio_info_from_caps            (GstAudioInfo *info,
                                                             const GstCaps *caps);
    GstCaps *           gst_audio_info_to_caps              (const GstAudioInfo *info);
    gboolean            gst_audio_info_convert              (const GstAudioInfo *info,
                                                             GstFormat src_fmt,
                                                             gint64 src_val,
                                                             GstFormat dest_fmt,
                                                             gint64 *dest_val);
    const GstAudioFormatInfo * gst_audio_format_get_info    (GstAudioFormat format);
    #define             GST_AUDIO_FORMAT_INFO_DEPTH         (info)
    #define             GST_AUDIO_FORMAT_INFO_ENDIANNESS    (info)
    #define             GST_AUDIO_FORMAT_INFO_FLAGS         (info)
    #define             GST_AUDIO_FORMAT_INFO_FORMAT        (info)
    #define             GST_AUDIO_FORMAT_INFO_IS_FLOAT      (info)
    #define             GST_AUDIO_FORMAT_INFO_IS_INTEGER    (info)
    #define             GST_AUDIO_FORMAT_INFO_IS_BIG_ENDIAN (info)
    #define             GST_AUDIO_FORMAT_INFO_IS_LITTLE_ENDIAN(info)
    #define             GST_AUDIO_FORMAT_INFO_IS_SIGNED     (info)
    #define             GST_AUDIO_FORMAT_INFO_NAME          (info)
    #define             GST_AUDIO_FORMAT_INFO_WIDTH         (info)
    #define             GST_AUDIO_INFO_BPF                  (info)
    #define             GST_AUDIO_INFO_BPS                  (info)
    #define             GST_AUDIO_INFO_CHANNELS             (info)
    #define             GST_AUDIO_INFO_DEPTH                (i)
    #define             GST_AUDIO_INFO_FLAGS                (info)
    #define             GST_AUDIO_INFO_FORMAT               (i)
    #define             GST_AUDIO_INFO_NAME                 (i)
    #define             GST_AUDIO_INFO_POSITION             (info,
                                                             c)
    #define             GST_AUDIO_INFO_RATE                 (info)
    #define             GST_AUDIO_INFO_WIDTH                (i)
    #define             GST_FRAMES_TO_CLOCK_TIME            (frames,
                                                             rate)
    #define             GST_CLOCK_TIME_TO_FRAMES            (clocktime,
                                                             rate)
    #define             GST_AUDIO_DEF_RATE
    GstBuffer *         gst_audio_buffer_clip               (GstBuffer *buffer,
                                                             GstSegment *segment,
                                                             gint rate,
                                                             gint bpf);

## Description

This library contains some helper functions for audio elements.

## Details

### enum GstAudioFlags

    typedef enum {
      GST_AUDIO_FLAG_NONE              = 0,
      GST_AUDIO_FLAG_UNPOSITIONED      = (1 << 0)
    } GstAudioFlags;

Extra audio flags

`GST_AUDIO_FLAG_NONE` | no valid flag
`GST_AUDIO_FLAG_UNPOSITIONED` | the position array explicitly contains unpositioned channels.

### enum GstAudioFormat

    typedef enum {
      GST_AUDIO_FORMAT_UNKNOWN,
      /* 8 bit */
      GST_AUDIO_FORMAT_S8,
      GST_AUDIO_FORMAT_U8,
      /* 16 bit */
      GST_AUDIO_FORMAT_S16LE,
      GST_AUDIO_FORMAT_S16BE,
      GST_AUDIO_FORMAT_U16LE,
      GST_AUDIO_FORMAT_U16BE,
      /* 24 bit in low 3 bytes of 32 bits*/
      GST_AUDIO_FORMAT_S24_32LE,
      GST_AUDIO_FORMAT_S24_32BE,
      GST_AUDIO_FORMAT_U24_32LE,
      GST_AUDIO_FORMAT_U24_32BE,
      /* 32 bit */
      GST_AUDIO_FORMAT_S32LE,
      GST_AUDIO_FORMAT_S32BE,
      GST_AUDIO_FORMAT_U32LE,
      GST_AUDIO_FORMAT_U32BE,
      /* 24 bit in 3 bytes*/
      GST_AUDIO_FORMAT_S24LE,
      GST_AUDIO_FORMAT_S24BE,
      GST_AUDIO_FORMAT_U24LE,
      GST_AUDIO_FORMAT_U24BE,
      /* 20 bit in 3 bytes*/
      GST_AUDIO_FORMAT_S20LE,
      GST_AUDIO_FORMAT_S20BE,
      GST_AUDIO_FORMAT_U20LE,
      GST_AUDIO_FORMAT_U20BE,
      /* 18 bit in 3 bytes*/
      GST_AUDIO_FORMAT_S18LE,
      GST_AUDIO_FORMAT_S18BE,
      GST_AUDIO_FORMAT_U18LE,
      GST_AUDIO_FORMAT_U18BE,
      /* float */
      GST_AUDIO_FORMAT_F32LE,
      GST_AUDIO_FORMAT_F32BE,
      GST_AUDIO_FORMAT_F64LE,
      GST_AUDIO_FORMAT_F64BE,
      /* native endianness equivalents */
      GST_AUDIO_FORMAT_S16 = _GST_AUDIO_FORMAT_NE(S16),
      GST_AUDIO_FORMAT_U16 = _GST_AUDIO_FORMAT_NE(U16),
      GST_AUDIO_FORMAT_S24_32 = _GST_AUDIO_FORMAT_NE(S24_32),
      GST_AUDIO_FORMAT_U24_32 = _GST_AUDIO_FORMAT_NE(U24_32),
      GST_AUDIO_FORMAT_S32 = _GST_AUDIO_FORMAT_NE(S32),
      GST_AUDIO_FORMAT_U32 = _GST_AUDIO_FORMAT_NE(U32),
      GST_AUDIO_FORMAT_S24 = _GST_AUDIO_FORMAT_NE(S24),
      GST_AUDIO_FORMAT_U24 = _GST_AUDIO_FORMAT_NE(U24),
      GST_AUDIO_FORMAT_S20 = _GST_AUDIO_FORMAT_NE(S20),
      GST_AUDIO_FORMAT_U20 = _GST_AUDIO_FORMAT_NE(U20),
      GST_AUDIO_FORMAT_S18 = _GST_AUDIO_FORMAT_NE(S18),
      GST_AUDIO_FORMAT_U18 = _GST_AUDIO_FORMAT_NE(U18),
      GST_AUDIO_FORMAT_F32 = _GST_AUDIO_FORMAT_NE(F32),
      GST_AUDIO_FORMAT_F64 = _GST_AUDIO_FORMAT_NE(F64)
    } GstAudioFormat;

Enum value describing the most common audio formats.

`GST_AUDIO_FORMAT_UNKNOWN` | unknown audio format
`GST_AUDIO_FORMAT_S8` | 8 bits in 8 bits, signed
`GST_AUDIO_FORMAT_U8` | 8 bits in 8 bits, unsigned
`GST_AUDIO_FORMAT_S16LE` | 16 bits in 16 bits, signed, little endian
`GST_AUDIO_FORMAT_S16BE` | 16 bits in 16 bits, signed, big endian
`GST_AUDIO_FORMAT_U16LE` | 16 bits in 16 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U16BE` | 16 bits in 16 bits, unsigned, big endian
`GST_AUDIO_FORMAT_S24_32LE` | 24 bits in 32 bits, signed, little endian
`GST_AUDIO_FORMAT_S24_32BE` | 24 bits in 32 bits, signed, big endian
`GST_AUDIO_FORMAT_U24_32LE` | 24 bits in 32 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U24_32BE` | 24 bits in 32 bits, unsigned, big endian
`GST_AUDIO_FORMAT_S32LE` | 32 bits in 32 bits, signed, little endian
`GST_AUDIO_FORMAT_S32BE` | 32 bits in 32 bits, signed, big endian
`GST_AUDIO_FORMAT_U32LE` | 32 bits in 32 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U32BE` | 32 bits in 32 bits, unsigned, big endian
`GST_AUDIO_FORMAT_S24LE` | 24 bits in 24 bits, signed, little endian
`GST_AUDIO_FORMAT_S24BE` | 24 bits in 24 bits, signed, big endian
`GST_AUDIO_FORMAT_U24LE` | 24 bits in 24 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U24BE` | 24 bits in 24 bits, unsigned, big endian
`GST_AUDIO_FORMAT_S20LE` | 20 bits in 24 bits, signed, little endian
`GST_AUDIO_FORMAT_S20BE` | 20 bits in 24 bits, signed, big endian
`GST_AUDIO_FORMAT_U20LE` | 20 bits in 24 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U20BE` | 20 bits in 24 bits, unsigned, big endian
`GST_AUDIO_FORMAT_S18LE` | 18 bits in 24 bits, signed, little endian
`GST_AUDIO_FORMAT_S18BE` | 18 bits in 24 bits, signed, big endian
`GST_AUDIO_FORMAT_U18LE` | 18 bits in 24 bits, unsigned, little endian
`GST_AUDIO_FORMAT_U18BE` | 18 bits in 24 bits, unsigned, big endian
`GST_AUDIO_FORMAT_F32LE` | 32-bit floating point samples, little endian
`GST_AUDIO_FORMAT_F32BE` | 32-bit floating point samples, big endian
`GST_AUDIO_FORMAT_F64LE` | 64-bit floating point samples, little endian
`GST_AUDIO_FORMAT_F64BE` | 64-bit floating point samples, big endian
`GST_AUDIO_FORMAT_S16` | 16 bits in 16 bits, signed, native endianness
`GST_AUDIO_FORMAT_U16` | 16 bits in 16 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_S24_32` | 24 bits in 32 bits, signed, native endianness
`GST_AUDIO_FORMAT_U24_32` | 24 bits in 32 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_S32` | 32 bits in 32 bits, signed, native endianness
`GST_AUDIO_FORMAT_U32` | 32 bits in 32 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_S24` | 24 bits in 24 bits, signed, native endianness
`GST_AUDIO_FORMAT_U24` | 24 bits in 24 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_S20` | 20 bits in 24 bits, signed, native endianness
`GST_AUDIO_FORMAT_U20` | 20 bits in 24 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_S18` | 18 bits in 24 bits, signed, native endianness
`GST_AUDIO_FORMAT_U18` | 18 bits in 24 bits, unsigned, native endianness
`GST_AUDIO_FORMAT_F32` | 32-bit floating point samples, native endianness
`GST_AUDIO_FORMAT_F64` | 64-bit floating point samples, native endianness

### enum GstAudioFormatFlags

    typedef enum {
      GST_AUDIO_FORMAT_FLAG_INTEGER  = (1 << 0),
      GST_AUDIO_FORMAT_FLAG_FLOAT    = (1 << 1),
      GST_AUDIO_FORMAT_FLAG_SIGNED   = (1 << 2),
      GST_AUDIO_FORMAT_FLAG_COMPLEX  = (1 << 4)
    } GstAudioFormatFlags;

The different audio flags that a format info can have.

`GST_AUDIO_FORMAT_FLAG_INTEGER` | integer samples
`GST_AUDIO_FORMAT_FLAG_FLOAT` | float samples
`GST_AUDIO_FORMAT_FLAG_SIGNED` | signed samples
`GST_AUDIO_FORMAT_FLAG_COMPLEX` | complex layout

### struct GstAudioFormatInfo

    struct GstAudioFormatInfo {
      GstAudioFormat format;
      const gchar *name;
      const gchar *description;
      GstAudioFormatFlags flags;
      gint endianness;
      gint width;
      gint depth;
      guint8 silence[8];

      GstAudioFormat unpack_format;
      GstAudioFormatUnpack unpack_func;
      GstAudioFormatPack pack_func;
    };

Information for an audio format.

GstAudioFormat `format`; | GstAudioFormat
const gchar *`name`; | string representation of the format
const gchar *`description`; | user readable description of the format
GstAudioFormatFlags `flags`; | GstAudioFormatFlags
gint `endianness`; | the endianness
gint `width`; | amount of bits used for one sample
gint `depth`; | amount of valid bits in `width`
guint8 `silence`[8]; | `width`/8 bytes with 1 silent sample
GstAudioFormat `unpack_format`; | the format of the unpacked samples
GstAudioFormatUnpack `unpack_func`; | function to unpack samples
GstAudioFormatPack `pack_func`; | function to pack samples

### struct GstAudioInfo

    struct GstAudioInfo {
      const GstAudioFormatInfo *finfo;
      GstAudioFlags             flags;
      GstAudioLayout            layout;
      gint                      rate;
      gint                      channels;
      gint                      bpf;
      GstAudioChannelPosition   position[64];
    };

Information describing audio properties. This information can be filled in from GstCaps with `gst_audio_info_from_caps()`.

Use the provided macros to access the info in this structure.

const GstAudioFormatInfo *`finfo`; | the format info of the audio
GstAudioFlags `flags`; | additional audio flags
GstAudioLayout `layout`; | audio layout
gint `rate`; | the audio sample rate
gint `channels`; | the number of channels
gint `bpf`; | the number of bytes for one frame, this is the size of one sample * `channels`
GstAudioChannelPosition `position`[64]; | the positions for each channel

### gst_audio_info_init ()

    void                gst_audio_info_init                 (GstAudioInfo *info);

Initialize `info` with default values.

`info` : | a GstAudioInfo

### gst_audio_info_from_caps ()

    gboolean            gst_audio_info_from_caps            (GstAudioInfo *info,
                                                             const GstCaps *caps);

Parse `caps` and update `info`.

`info` : | a GstAudioInfo
`caps` : | a GstCaps
Returns : | TRUE if `caps` could be parsed

### gst_audio_info_to_caps ()

    GstCaps *           gst_audio_info_to_caps              (const GstAudioInfo *info);

Convert the values of `info` into a GstCaps.

`info` : | a GstAudioInfo
Returns : | the new GstCaps containing the info of `info`. [transfer full]

### gst_audio_info_convert ()

    gboolean            gst_audio_info_convert              (const GstAudioInfo *info,
                                                             GstFormat src_fmt,
                                                             gint64 src_val,
                                                             GstFormat dest_fmt,
                                                             gint64 *dest_val);

### gst_audio_format_get_info ()

    const GstAudioFormatInfo * gst_audio_format_get_info    (GstAudioFormat format);

Get the GstAudioFormatInfo for `format`

`format` : | a GstAudioFormat
Returns : | The GstAudioFormatInfo for `format`.

### GST_AUDIO_FORMAT_INFO_DEPTH()

    #define GST_AUDIO_FORMAT_INFO_DEPTH(info)            ((info)->depth)

### GST_AUDIO_FORMAT_INFO_ENDIANNESS()

    #define GST_AUDIO_FORMAT_INFO_ENDIANNESS(info)       ((info)->endianness)

### GST_AUDIO_FORMAT_INFO_FLAGS()

    #define GST_AUDIO_FORMAT_INFO_FLAGS(info)            ((info)->flags)

### GST_AUDIO_FORMAT_INFO_FORMAT()

    #define GST_AUDIO_FORMAT_INFO_FORMAT(info)           ((info)->format)

### GST_AUDIO_FORMAT_INFO_IS_FLOAT()

    #define GST_AUDIO_FORMAT_INFO_IS_FLOAT(info)         !!((info)->flags & GST_AUDIO_FORMAT_FLAG_FLOAT)

### GST_AUDIO_FORMAT_INFO_IS_INTEGER()

    #define GST_AUDIO_FORMAT_INFO_IS_INTEGER(info)       !!((info)->flags & GST_AUDIO_FORMAT_FLAG_INTEGER)

### GST_AUDIO_FORMAT_INFO_IS_BIG_ENDIAN()

    #define GST_AUDIO_FORMAT_INFO_IS_BIG_ENDIAN(info)    ((info)->endianness == G_BIG_ENDIAN)

### GST_AUDIO_FORMAT_INFO_IS_LITTLE_ENDIAN()

    #define GST_AUDIO_FORMAT_INFO_IS_LITTLE_ENDIAN(info) ((info)->endianness == G_LITTLE_ENDIAN)

### GST_AUDIO_FORMAT_INFO_IS_SIGNED()

    #define GST_AUDIO_FORMAT_INFO_IS_SIGNED(info)        !!((info)->flags & GST_AUDIO_FORMAT_FLAG_SIGNED)

### GST_AUDIO_FORMAT_INFO_NAME()

    #define GST_AUDIO_FORMAT_INFO_NAME(info)             ((info)->name)

### GST_AUDIO_FORMAT_INFO_WIDTH()

    #define GST_AUDIO_FORMAT_INFO_WIDTH(info)            ((info)->width)

### GST_AUDIO_INFO_BPF()

    #define GST_AUDIO_INFO_BPF(info)             ((info)->bpf)

### GST_AUDIO_INFO_BPS()

    #define GST_AUDIO_INFO_BPS(info)             (GST_AUDIO_INFO_DEPTH(info) >> 3)

### GST_AUDIO_INFO_CHANNELS()

    #define GST_AUDIO_INFO_CHANNELS(info)        ((info)->channels)

### GST_AUDIO_INFO_DEPTH()

    #define GST_AUDIO_INFO_DEPTH(i)              (GST_AUDIO_FORMAT_INFO_DEPTH((i)->finfo))

### GST_AUDIO_INFO_FLAGS()

    #define GST_AUDIO_INFO_FLAGS(info)           ((info)->flags)

### GST_AUDIO_INFO_FORMAT()

    #define GST_AUDIO_INFO_FORMAT(i)             (GST_AUDIO_FORMAT_INFO_FORMAT((i)->finfo))

### GST_AUDIO_INFO_NAME()

    #define GST_AUDIO_INFO_NAME(i)               (GST_AUDIO_FORMAT_INFO_NAME((i)->finfo))

### GST_AUDIO_INFO_POSITION()

    #define GST_AUDIO_INFO_POSITION(info,c)      ((info)->position[c])

### GST_AUDIO_INFO_RATE()

    #define GST_AUDIO_INFO_RATE(info)            ((info)->rate)

### GST_AUDIO_INFO_WIDTH()

    #define GST_AUDIO_INFO_WIDTH(i)              (GST_AUDIO_FORMAT_INFO_WIDTH((i)->finfo))

### GST_FRAMES_TO_CLOCK_TIME()

    #define             GST_FRAMES_TO_CLOCK_TIME(frames, rate)

Calculate clocktime from sample `frames` and `rate`.

`frames` : | sample frames
`rate` : | sampling rate

### GST_CLOCK_TIME_TO_FRAMES()

    #define             GST_CLOCK_TIME_TO_FRAMES(clocktime, rate)

Calculate frames from `clocktime` and sample `rate`.

`clocktime` : | clock time
`rate` : | sampling rate

### GST_AUDIO_DEF_RATE

    #define GST_AUDIO_DEF_RATE 44100

Standard sampling rate used in consumer audio.

### gst_audio_buffer_clip ()

    GstBuffer *         gst_audio_buffer_clip               (GstBuffer *buffer,
                                                             GstSegment *segment,
                                                             gint rate,
                                                             gint bpf);

Clip the buffer to the given `GstSegment`.

After calling this function the caller does not own a reference to `buffer` anymore.

`buffer` : | The buffer to clip.
`segment` : | Segment in `GST_FORMAT_TIME` or `GST_FORMAT_DEFAULT` to which the buffer should be clipped.
`rate` : | sample rate.
`bpf` : | size of one audio frame in bytes. This is the size of one sample * channels.
Returns : | `NULL` if the buffer is completely outside the configured segment, otherwise the clipped buffer is returned. If the buffer has no timestamp, it is assumed to be inside the segment and is not clipped

Since 0.10.14