audioconvert

Audioconvert converts raw audio buffers between various possible formats. It supports integer to float conversion, width/depth conversion, signedness and endianness conversion and channel transformations (ie. upmixing and downmixing), as well as dithering and noise-shaping.

Example launch line

 gst-launch-1.0 -v -m audiotestsrc ! audioconvert ! audio/x-raw,format=S8,channels=2 ! level ! fakesink silent=TRUE

This pipeline converts audio to 8-bit. The level element shows that the output levels still match the one for a sine wave.

 gst-launch-1.0 -v -m uridecodebin uri=file:///path/to/audio.flac ! audioconvert ! vorbisenc ! oggmux ! filesink location=audio.ogg

The vorbis encoder takes float audio data instead of the integer data output by most other audio elements. This pipeline decodes a FLAC audio file (or any other audio file for which decoders are installed) and re-encodes it into an Ogg/Vorbis audio file.

A mix matrix can be passed to audioconvert, that will govern the remapping of input to output channels.

Example matrix generation code

To generate the matrix using code:

 GValue v = G_VALUE_INIT;
 GValue v2 = G_VALUE_INIT;
 GValue v3 = G_VALUE_INIT;

 g_value_init (&v2, GST_TYPE_ARRAY);
 g_value_init (&v3, G_TYPE_FLOAT);
 g_value_set_float (&v3, 1);
 gst_value_array_append_value (&v2, &v3);
 g_value_unset (&v3);
 [ Repeat for as many float as your input channels - unset and reinit v3 ]
 g_value_init (&v, GST_TYPE_ARRAY);
 gst_value_array_append_value (&v, &v2);
 g_value_unset (&v2);
 [ Repeat for as many v2's as your output channels - unset and reinit v2]
 g_object_set_property (G_OBJECT (audioconvert), "mix-matrix", &v);
 g_value_unset (&v);

Example launch line

 gst-launch-1.0 audiotestsrc ! audio/x-raw, channels=4 ! audioconvert mix-matrix="<<(float)1.0, (float)0.0, (float)0.0, (float)0.0>, <(float)0.0, (float)1.0, (float)0.0, (float)0.0>>" ! audio/x-raw,channels=2 ! autoaudiosink

If an empty mix matrix is specified, a (potentially truncated) identity matrix will be generated.

Example empty matrix generation code

 GValue v = G_VALUE_INIT;

 g_value_init (&v, GST_TYPE_ARRAY);
 g_object_set_property (G_OBJECT (audioconvert), "mix-matrix", &v);
 g_value_unset (&v);

Example empty matrix launch line

 gst-launch-1.0 -v audiotestsrc ! audio/x-raw,channels=8 ! audioconvert mix-matrix="<>" ! audio/x-raw,channels=16,channel-mask=\(bitmask\)0x0000000000000000 ! fakesink

Hierarchy

GObject
    ╰──GInitiallyUnowned
        ╰──GstObject
            ╰──GstElement
                ╰──GstBaseTransform
                    ╰──audioconvert

Factory details

Authors: – Benjamin Otte

Classification:Filter/Converter/Audio

Rank – primary

Plugin – audioconvert

Package – GStreamer Base Plug-ins

Pad Templates

sink

audio/x-raw:
         format: { F64LE, F64BE, F32LE, F32BE, S32LE, S32BE, U32LE, U32BE, S24_32LE, S24_32BE, U24_32LE, U24_32BE, S24LE, S24BE, U24LE, U24BE, S20LE, S20BE, U20LE, U20BE, S18LE, S18BE, U18LE, U18BE, S16LE, S16BE, U16LE, U16BE, S8, U8 }
           rate: [ 1, 2147483647 ]
       channels: [ 1, 2147483647 ]
         layout: { (string)interleaved, (string)non-interleaved }

Presencealways

Directionsink

Object typeGstPad


src

audio/x-raw:
         format: { F64LE, F64BE, F32LE, F32BE, S32LE, S32BE, U32LE, U32BE, S24_32LE, S24_32BE, U24_32LE, U24_32BE, S24LE, S24BE, U24LE, U24BE, S20LE, S20BE, U20LE, U20BE, S18LE, S18BE, U18LE, U18BE, S16LE, S16BE, U16LE, U16BE, S8, U8 }
           rate: [ 1, 2147483647 ]
       channels: [ 1, 2147483647 ]
         layout: { (string)interleaved, (string)non-interleaved }

Presencealways

Directionsrc

Object typeGstPad


Properties

dithering

“dithering” GstAudioDitherMethod *

Selects between different dithering methods.

Flags : Read / Write

Default value : tpdf (2)


mix-matrix

“mix-matrix” GstValueArray *

Transformation matrix for input/output channels

Flags : Read / Write


noise-shaping

“noise-shaping” GstAudioNoiseShapingMethod *

Selects between different noise shaping methods.

Flags : Read / Write

Default value : none (0)


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