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Update documentation for audio/raw properties to cover format=float case.

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Original commit message from CVS:
Update documentation for audio/raw properties to cover format=float case.
Please check this for correctness.
This commit is contained in:
Richard Boulton 2001-05-01 13:54:41 +00:00
parent b67a5bf39d
commit 317c1c5b30
1 changed files with 54 additions and 28 deletions
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82
docs/fwg/gst-plugin-writers-guide.sgml
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@ -254,43 +254,69 @@
<para>
<emphasis>audio/raw</emphasis>
- Unstructured and uncompressed raw audio data.
</para><para>
<emphasis>law</emphasis>
- The law used to describe the data. This is an integer for which
there are three valid values: 0 for linear, 1 for
mu law, 2 for A law.
</para><para>
<emphasis>endianness</emphasis>
- The order of bytes in a sample. This is a boolean:
0 means little-endian (ie, bytes are least significant first),
1 means big-endian (ie, most significant byte first).
</para><para>
<emphasis>signed</emphasis>
- Whether the samples are signed or not. This is a boolean:
0 means unsigned, 1 means signed.
</para><para>
<emphasis>width</emphasis>
- The number of bits per sample. This is extremely likely to be
a multiple of 8, but as ever this is up to each element supporting
this format to specify.
</para><para>
<emphasis>depth</emphasis>
- The number of bits used per sample. This must be less than or
equal to the width: if less than the width, the low bits are
assumed to be the ones used. For example, width=32, depth=24
means that each sample is stored in a 32 bit word, but only the
low 24 bits are actually used.
</para><para>
<emphasis>rate</emphasis>
- The sample rate of the data, in samples per second.
</para><para>
<emphasis>channels</emphasis>
- The number of channels of audio data.
</para><para>
<emphasis>format</emphasis>
- This describes the format in which the audio data is passed.
This is a string for which there are currently two valid values:
"int" for integer data and "float" for floating point data.
</para><para>
<emphasis>law</emphasis>
- Valid only if format=int. The law used to describe the data.
This is an integer for which there are three valid values: 0 for
linear, 1 for mu law, 2 for A law.
</para><para>
<emphasis>endianness</emphasis>
- Valid only if format=int. The order of bytes in a sample. This
is a boolean: 0 means little-endian (ie, bytes are least
significant first), 1 means big-endian (ie, most significant byte
first).
</para><para>
<emphasis>signed</emphasis>
- Valid only if format=int. Whether the samples are signed or not.
This is a boolean: 0 means unsigned, 1 means signed.
</para><para>
<emphasis>width</emphasis>
- Valid only if format=int. The number of bits per sample. This
is extremely likely to be a multiple of 8, but as ever this is up
to each element supporting this format to specify.
</para><para>
<emphasis>depth</emphasis>
- Valid only if format=int. The number of bits used per sample.
This must be less than or equal to the width: if less than the
width, the low bits are assumed to be the ones used. For example,
width=32, depth=24 means that each sample is stored in a 32 bit
word, but only the low 24 bits are actually used.
</para><para>
<emphasis>layout</emphasis>
- Valid only if format=float. A string representing the way in
which the floating point data is represented. For now, the only
valid value is gfloat, meaning that the data is passed as a series
of gfloat values.
</para><para>
<emphasis>intercept</emphasis>
- Valid only if format=float. A floating point value representing
the value that the signal "centres" on.
</para><para>
<emphasis>slope</emphasis>
- Valid only if format=float. A floating point value representing
how far the signal deviates from the intercept. So a slope of 1.0
and an intercept of 0.0 would mean an audio signal with minimum
and maximum values of -1.0 and 1.0. A slope of 0.5 and intercept
of 0.5 would represent values in the range 0.0 to 1.0.
</para>
<para>
For example: 16 bit, unsigned, linear, monophonic, big-endian,
For example: 16 bit integer, unsigned, linear, monophonic, big-endian,
44100KHz audio would be represented by
"law=0,endianness=1,signed=0,width=16,depth=16,rate=44100,channels=1"
"format=int,law=0,endianness=1,signed=0,width=16,depth=16,rate=44100,channels=1"
and floating point, using gfloat's, in the range -1.0 to 1.0,
8000KHz stereo audio would be represented by
"format=float,layout=gfloat,intercept=0.0,slope=1.0,rate=8000,channels=2"
</para>
</listitem>
</itemizedlist>