Playback Channel: Spice-GTK Reference Manual

Playback Channel

Playback Channel — audio stream for playback

Stability Level

Stable, unless otherwise indicated

Functions

void	spice_playback_channel_set_delay ()

Properties

guint	min-latency	Read / Write
gboolean	mute	Read / Write
guint	nchannels	Read / Write
gpointer	volume	Read / Write

Signals

void	playback-data	Run First
void	playback-get-delay	Run First
void	playback-start	Run First
void	playback-stop	Run First

Types and Values

struct	SpicePlaybackChannel
struct	SpicePlaybackChannelClass

Object Hierarchy

    GObject
    ╰── SpiceChannel
        ╰── SpicePlaybackChannel

Includes

#include <spice-client.h>

Description

SpicePlaybackChannel class handles an audio playback stream. The audio data is received via “playback-data” signal, and is controlled by the guest with “playback-stop” and “playback-start” signal events.

Note: You may be interested to let the SpiceAudio class play and record audio channels for your application.

Functions

spice_playback_channel_set_delay ()

void
spice_playback_channel_set_delay (SpicePlaybackChannel *channel,
                                  guint32 delay_ms);

Adjust the multimedia time according to the delay.

Parameters

channel	a SpicePlaybackChannel
delay_ms	the delay in ms

Types and Values

struct SpicePlaybackChannel

struct SpicePlaybackChannel;

The SpicePlaybackChannel struct is opaque and should not be accessed directly.

struct SpicePlaybackChannelClass

struct SpicePlaybackChannelClass {
    SpiceChannelClass parent_class;

    /* signals */
    void (*playback_start)(SpicePlaybackChannel *channel,
                           gint format, gint channels, gint freq);
    void (*playback_data)(SpicePlaybackChannel *channel, gpointer *data, gint size);
    void (*playback_stop)(SpicePlaybackChannel *channel);
};

Class structure for SpicePlaybackChannel.

Members

`playback_start` ()	Signal class handler for the “playback-start” signal.
`playback_data` ()	Signal class handler for the “playback-data” signal.
`playback_stop` ()	Signal class handler for the “playback-stop” signal.

Property Details

The `“min-latency”` property

  “min-latency”              guint

Playback min buffer size (ms).

Flags: Read / Write

Default value: 200

The `“mute”` property

  “mute”                     gboolean

Mute.

Flags: Read / Write

Default value: FALSE

The `“nchannels”` property

  “nchannels”                guint

Number of Channels.

Flags: Read / Write

Allowed values: <= 255

Default value: 2

The `“volume”` property

  “volume”                   gpointer

Playback volume.

Flags: Read / Write

Signal Details

The `“playback-data”` signal

void
user_function (SpicePlaybackChannel *channel,
               gpointer              data,
               gint                  data_size,
               gpointer              user_data)

Provide audio data to be played.

Parameters

channel	the SpicePlaybackChannel that emitted the signal
data	pointer to audio data
data_size	size in byte of `data`
user_data	user data set when the signal handler was connected.

Flags: Run First

The `“playback-get-delay”` signal

void
user_function (SpicePlaybackChannel *channel,
               gpointer              user_data)

Notify when the current playback delay is requested

Parameters

channel	the SpicePlaybackChannel that emitted the signal
user_data	user data set when the signal handler was connected.

Flags: Run First

The `“playback-start”` signal

void
user_function (SpicePlaybackChannel *channel,
               gint                  format,
               gint                  channels,
               gint                  rate,
               gpointer              user_data)

Notify when the playback should start, and provide audio format characteristics.

Parameters

channel	the SpicePlaybackChannel that emitted the signal
format	a SPICE_AUDIO_FMT
channels	number of channels
rate	audio rate
latency	minimum playback latency in ms
user_data	user data set when the signal handler was connected.

Flags: Run First

The `“playback-stop”` signal

void
user_function (SpicePlaybackChannel *channel,
               gpointer              user_data)

Notify when the playback should stop.

Parameters

channel	the SpicePlaybackChannel that emitted the signal
user_data	user data set when the signal handler was connected.

Flags: Run First