Audio-channels

GstAudio.prototype.audio_channel_get_fallback_mask

function GstAudio.prototype.audio_channel_get_fallback_mask(channels: Number): {
    // javascript wrapper for 'gst_audio_channel_get_fallback_mask'
}

Get the fallback channel-mask for the given number of channels.

This function returns a reasonable fallback channel-mask and should be called as a last resort when the specific channel map is unknown.

Since : 1.8

GstAudio.prototype.audio_channel_positions_from_mask

function GstAudio.prototype.audio_channel_positions_from_mask(channels: Number, channel_mask: Number, position: [ GstAudio.AudioChannelPosition ]): {
    // javascript wrapper for 'gst_audio_channel_positions_from_mask'
}

Convert the channels present in channel_mask to a position array (which should have at least channels entries ensured by caller). If channel_mask is set to 0, it is considered as 'not present' for purpose of conversion. A partially valid channel_mask with less bits set than the number of channels is considered valid.

GstAudio.prototype.audio_channel_positions_to_mask

function GstAudio.prototype.audio_channel_positions_to_mask(position: [ GstAudio.AudioChannelPosition ], channels: Number, force_order: Number): {
    // javascript wrapper for 'gst_audio_channel_positions_to_mask'
}

Convert the position array of channels channels to a bitmask.

If force_order is true it additionally checks if the channels are in the order required by GStreamer.

GstAudio.prototype.audio_channel_positions_to_string

function GstAudio.prototype.audio_channel_positions_to_string(position: [ GstAudio.AudioChannelPosition ], channels: Number): {
    // javascript wrapper for 'gst_audio_channel_positions_to_string'
}

Converts position to a human-readable string representation for debugging purposes.

Since : 1.10

GstAudio.prototype.audio_channel_positions_to_valid_order

function GstAudio.prototype.audio_channel_positions_to_valid_order(position: [ GstAudio.AudioChannelPosition ], channels: Number): {
    // javascript wrapper for 'gst_audio_channel_positions_to_valid_order'
}

Reorders the channel positions in position from any order to the GStreamer channel order.

GstAudio.prototype.audio_check_valid_channel_positions

function GstAudio.prototype.audio_check_valid_channel_positions(position: [ GstAudio.AudioChannelPosition ], channels: Number, force_order: Number): {
    // javascript wrapper for 'gst_audio_check_valid_channel_positions'
}

Checks if position contains valid channel positions for channels channels. If force_order is true it additionally checks if the channels are in the order required by GStreamer.

GstAudio.prototype.audio_get_channel_reorder_map

function GstAudio.prototype.audio_get_channel_reorder_map(channels: Number, from: [ GstAudio.AudioChannelPosition ], to: [ GstAudio.AudioChannelPosition ], reorder_map: [ Number ]): {
    // javascript wrapper for 'gst_audio_get_channel_reorder_map'
}

Returns a reorder map for from to to that can be used in custom channel reordering code, e.g. to convert from or to the GStreamer channel order. from and to must contain the same number of positions and the same positions, only in a different order.

The resulting reorder_map can be used for reordering by assigning channel i of the input to channel reorder_map[i] of the output.

GstAudio.prototype.audio_reorder_channels

function GstAudio.prototype.audio_reorder_channels(data: [ Number ], size: Number, format: GstAudio.AudioFormat, channels: Number, from: [ GstAudio.AudioChannelPosition ], to: [ GstAudio.AudioChannelPosition ]): {
    // javascript wrapper for 'gst_audio_reorder_channels'
}

Reorders data from the channel positions from to the channel positions to. from and to must contain the same number of positions and the same positions, only in a different order.

Note: this function assumes the audio data is in interleaved layout

GstAudio.AudioChannelPosition

Audio channel positions.

These are the channels defined in SMPTE 2036-2-2008 Table 1 for 22.2 audio systems with the Surround and Wide channels from DTS Coherent Acoustics (v.1.3.1) and 10.2 and 7.1 layouts. In the caps the actual channel layout is expressed with a channel count and a channel mask, which describes the existing channels. The positions in the bit mask correspond to the enum values. For negotiation it is allowed to have more bits set in the channel mask than the number of channels to specify the allowed channel positions but this is not allowed in negotiated caps. It is not allowed in any situation other than the one mentioned below to have less bits set in the channel mask than the number of channels.

GST_AUDIO_CHANNEL_POSITION_MONO can only be used with a single mono channel that has no direction information and would be mixed into all directional channels. This is expressed in caps by having a single channel and no channel mask.

GST_AUDIO_CHANNEL_POSITION_NONE can only be used if all channels have this position. This is expressed in caps by having a channel mask with no bits set.

As another special case it is allowed to have two channels without a channel mask. This implicitly means that this is a stereo stream with a front left and front right channel.