GstAudio.DsdInfo¶

Fields¶

Name	Type	Access	Description
channels	`int`	r/w	number of channels (must be at least 1)
flags	`GstAudio.AudioFlags`	r/w
format	`GstAudio.DsdFormat`	r/w	DSD grouping format
layout	`GstAudio.AudioLayout`	r/w	audio layout
positions	[`GstAudio.AudioChannelPosition`]	r/w	positions for each channel
rate	`int`	r/w	DSD rate
reversed_bytes	`bool`	r/w	true if the DSD bits in the data bytes are reversed, that is, the least significant bit comes first

Methods¶

class	`from_caps` (caps)
class	`init` ()
class	`new` ()
class	`new_from_caps` (caps)
	`copy` ()
	`free` ()
	`is_equal` (other)
	`set_format` (format, rate, channels, positions)
	`to_caps` ()

Details¶

class GstAudio.DsdInfo¶

Information describing DSD audio properties.

In DSD, the “sample format” is the bit. Unlike PCM, there are no further “sample formats” in DSD. However, in software, DSD bits are grouped into bytes (since dealing with individual bits is impractical), and these bytes in turn are grouped into words. This becomes relevant when interleaving channels and transmitting DSD data through audio APIs. The different types of grouping DSD bytes are referred to as the “DSD grouping forma” or just “DSD format”. GstAudio.DsdFormat has a list of valid ways of grouping DSD bytes into words.

DSD rates are equivalent to PCM sample rates, except that they specify how many DSD bytes are consumed per second. This refers to the bytes per second _per channel_; the rate does not change when the number of channel changes. (Strictly speaking, it would be more correct to measure the *bits* per second, since the bit is the DSD “sample format”, but it is more practical to use bytes.) In DSD, bit rates are always an integer multiple of the CD audio rate (44100) or the DAT rate (48000). DSD64-44x is 44100 * 64 = 2822400 bits per second, or 352800 bytes per second (the latter would be used in this info structure). DSD64-48x is 48000 * 64 = 3072000 bits per second, or 384000 bytes per second. #GST_DSD_MAKE_DSD_RATE_44x can be used for specifying DSD-44x rates, *and #GST_DSD_MAKE_DSD_RATE_48x can be used for specifying DSD-48x ones. Also, since DSD-48x is less well known, when the multiplier is given without the 44x/48x specifier, 44x is typically implied.

It is important to know that in DSD, different format widths correspond to different playtimes. That is, a word with 32 DSD bits covers two times as much playtime as a word with 16 DSD bits. This is in contrast to PCM, where one word (= one PCM sample) always covers a time period of 1/samplerate, no matter how many bits a PCM sample is made of. For this reason, DSD and PCM widths and strides cannot be used the same way.

Multiple channels are arranged in DSD data either interleaved or non- interleaved. This is similar to PCM. Interleaved layouts rotate between channels and words. First, word 0 of channel 0 is present. Then word 0 of channel 1 follows. Then word 0 of channel 2 etc. until all channels are through, then comes word 1 of channel 0 etc.

Non-interleaved data is planar. First, all words of channel 0 are present, then all words of channel 1 etc. Unlike interleaved data, non-interleaved data can be sparse, that is, there can be space in between the planes. the positions array specifies the plane offsets.

In uncommon cases, the DSD bits in the data bytes can be stored in reverse order. For example, normally, in DSDU8, the first byte contains DSD bits 0 to 7, and the most significant bit of that byte is DSD bit 0. If this order is reversed, then bit 7 is the first one instead. In that ase, reversed_bytes is set to True.

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

New in version 1.24.

classmethod from_caps(caps)[source]¶

Parameters:

caps (Gst.Caps) – a Gst.Caps

Returns:

True if caps could be parsed

info:: a GstAudio.DsdInfo

Return type:

(bool, info: GstAudio.DsdInfo)

Parse caps and update info.

New in version 1.24.

classmethod init()[source]¶

Returns:: a GstAudio.DsdInfo
Return type:: info: GstAudio.DsdInfo

Initialize info with default values.

New in version 1.24.

classmethod new()[source]¶

Returns:: a new GstAudio.DsdInfo. free with GstAudio.DsdInfo.free().
Return type:: GstAudio.DsdInfo

Allocate a new GstAudio.DsdInfo that is also initialized with GstAudio.DsdInfo.init().

New in version 1.24.

classmethod new_from_caps(caps)[source]¶

Parameters:: caps (Gst.Caps) – a Gst.Caps
Returns:: A GstAudio.DsdInfo, or None if caps couldn’t be parsed
Return type:: GstAudio.DsdInfo

Parse caps to generate a GstAudio.DsdInfo.

New in version 1.24.

copy()[source]¶

Returns:: a new GstAudio.DsdInfo. free with GstAudio.DsdInfo.free.
Return type:: GstAudio.DsdInfo

Copy a GstAudio.DsdInfo structure.

New in version 1.24.

free()[source]¶: Free a GstAudio.DsdInfo structure previously allocated with GstAudio.DsdInfo.new() or GstAudio.DsdInfo.copy().

New in version 1.24.

is_equal(other)[source]¶

Parameters:: other (GstAudio.DsdInfo) – a GstAudio.DsdInfo
Returns:: True if self and other are equal, else False.
Return type:: bool

Compares two GstAudio.DsdInfo and returns whether they are equal or not

New in version 1.24.

set_format(format, rate, channels, positions)[source]¶

Parameters:

format (GstAudio.DsdFormat) – the format
rate (int) – the DSD rate
channels (int) – the number of channels
positions ([GstAudio.AudioChannelPosition] or None) – the channel positions

Set the default info for the DSD info of format and rate and channels.

Note: This initializes self first, no values are preserved.

New in version 1.24.

to_caps()[source]¶

Returns:: the new Gst.Caps containing the info of self.
Return type:: Gst.Caps

Convert the values of self into a Gst.Caps.

New in version 1.24.