# decodebin

GstBin that auto-magically constructs a decoding pipeline using available decoders and demuxers via auto-plugging.

decodebin is considered stable now and replaces the old decodebin element. uridecodebin uses decodebin internally and is often more convenient to use, as it creates a suitable source element as well.

## Hierarchy

    GObject
        ╰──GInitiallyUnowned
            ╰──GstObject
                ╰──GstElement
                    ╰──GstBin
                        ╰──decodebin

## Implemented interfaces

    GstChildProxy

## Factory details

Authors: – Edward Hervey , Sebastian Dröge

Classification: – `Generic/Bin/Decoder`

Rank – none

Plugin – playback

Package – GStreamer Base Plug-ins

## Pad Templates

### `sink`

    ANY

Presence – always

Direction – sink

Object type – GstPad

### `src_%u`

    ANY

Presence – sometimes

Direction – src

Object type – GstPad

## Signals

### autoplug-continue

    gboolean
    autoplug_continue_callback (GstElement * bin,
                                GstPad * pad,
                                GstCaps * caps,
                                gpointer udata)

    def autoplug_continue_callback (bin, pad, caps, udata):
        #python callback for the 'autoplug-continue' signal

    function autoplug_continue_callback(bin: GstElement * bin, pad: GstPad * pad, caps: GstCaps * caps, udata: gpointer udata): {
        // javascript callback for the 'autoplug-continue' signal
    }

This signal is emitted whenever decodebin finds a new stream. It is emitted before looking for any elements that can handle that stream.

> Invocation of signal handlers stops after the first signal handler returns FALSE. Signal handlers are invoked in the order they were connected in.

Parameters:

`bin` –

The decodebin.

`pad` –

The GstPad.

`caps` –

The GstCaps found.

`udata` –
No description available
Returns (gboolean) –

TRUE if you wish decodebin to look for elements that can handle the given caps. If FALSE, those caps will be considered as final and the pad will be exposed as such (see 'pad-added' signal of GstElement).

Flags: Run Last

### autoplug-factories

    GValueArray *
    autoplug_factories_callback (GstElement * bin,
                                 GstPad * pad,
                                 GstCaps * caps,
                                 gpointer udata)

    def autoplug_factories_callback (bin, pad, caps, udata):
        #python callback for the 'autoplug-factories' signal

    function autoplug_factories_callback(bin: GstElement * bin, pad: GstPad * pad, caps: GstCaps * caps, udata: gpointer udata): {
        // javascript callback for the 'autoplug-factories' signal
    }

This signal is emitted when an array of possible factories for caps on pad is needed. Decodebin will by default return an array with all compatible factories, sorted by rank.

If this function returns NULL, pad will be exposed as a final caps.

If this function returns an empty array, the pad will be considered as having an unhandled type media type.

> Only the signal handler that is connected first will ever by invoked. Don't connect signal handlers with the G_CONNECT_AFTER flag to this signal, they will never be invoked!

Parameters:

`bin` –

The decodebin.

`pad` –

The GstPad.

`caps` –

The GstCaps found.

`udata` –
No description available
Returns (GValueArray *) –

a GValueArray* with a list of factories to try. The factories are by default tried in the returned order or based on the index returned by "autoplug-select".

Flags: Run Last

### autoplug-query

    gboolean
    autoplug_query_callback (GstElement * bin,
                             GstPad * pad,
                             GstElement * child,
                             GstQuery * query,
                             gpointer udata)

    def autoplug_query_callback (bin, pad, child, query, udata):
        #python callback for the 'autoplug-query' signal

    function autoplug_query_callback(bin: GstElement * bin, pad: GstPad * pad, child: GstElement * child, query: GstQuery * query, udata: gpointer udata): {
        // javascript callback for the 'autoplug-query' signal
    }

This signal is emitted whenever an autoplugged element that is not linked downstream yet and not exposed does a query. It can be used to tell the element about the downstream supported caps for example.

Parameters:

`bin` –

The decodebin.

`pad` –

The GstPad.

`child` –

The child element doing the query

`query` –

The GstQuery.

`udata` –
No description available
Returns (gboolean) –

TRUE if the query was handled, FALSE otherwise.

Flags: Run Last

### autoplug-select

    GstAutoplugSelectResult *
    autoplug_select_callback (GstElement * bin,
                              GstPad * pad,
                              GstCaps * caps,
                              GstElementFactory * factory,
                              gpointer udata)

    def autoplug_select_callback (bin, pad, caps, factory, udata):
        #python callback for the 'autoplug-select' signal

    function autoplug_select_callback(bin: GstElement * bin, pad: GstPad * pad, caps: GstCaps * caps, factory: GstElementFactory * factory, udata: gpointer udata): {
        // javascript callback for the 'autoplug-select' signal
    }

This signal is emitted once decodebin has found all the possible GstElementFactory that can be used to handle the given caps. For each of those factories, this signal is emitted.

The signal handler should return a GstAutoplugSelectResult enum value indicating what decodebin should do next.

A value of try will try to autoplug an element from factory.

A value of expose will expose pad without plugging any element to it.

A value of skip will skip factory and move to the next factory.

> The signal handler will not be invoked if any of the previously registered signal handlers (if any) return a value other than GST_AUTOPLUG_SELECT_TRY. Which also means that if you return GST_AUTOPLUG_SELECT_TRY from one signal handler, handlers that get registered next (again, if any) can override that decision.

Parameters:

`bin` –

The decodebin.

`pad` –

The GstPad.

`caps` –

The GstCaps.

`factory` –

A GstElementFactory to use.

`udata` –
No description available
Returns (GstAutoplugSelectResult *) –

a GstAutoplugSelectResult that indicates the required operation. the default handler will always return try.

Flags: Run Last

### autoplug-sort

    GValueArray *
    autoplug_sort_callback (GstElement * bin,
                            GstPad * pad,
                            GstCaps * caps,
                            GValueArray * factories,
                            gpointer udata)

    def autoplug_sort_callback (bin, pad, caps, factories, udata):
        #python callback for the 'autoplug-sort' signal

    function autoplug_sort_callback(bin: GstElement * bin, pad: GstPad * pad, caps: GstCaps * caps, factories: GValueArray * factories, udata: gpointer udata): {
        // javascript callback for the 'autoplug-sort' signal
    }

Once decodebin has found the possible GstElementFactory objects to try for caps on pad, this signal is emitted. The purpose of the signal is for the application to perform additional sorting or filtering on the element factory array.

The callee should copy and modify factories or return NULL if the order should not change.

> Invocation of signal handlers stops after one signal handler has returned something else than NULL. Signal handlers are invoked in the order they were connected in. Don't connect signal handlers with the G_CONNECT_AFTER flag to this signal, they will never be invoked!

Parameters:

`bin` –

The decodebin.

`pad` –

The GstPad.

`caps` –

The GstCaps.

`factories` –

A GValueArray of possible GstElementFactory to use.

`udata` –
No description available
Returns (GValueArray *) –

A new sorted array of GstElementFactory objects.

Flags: Run Last

### drained

    drained_callback (GstElement * bin,
                      gpointer udata)

    def drained_callback (bin, udata):
        #python callback for the 'drained' signal

    function drained_callback(bin: GstElement * bin, udata: gpointer udata): {
        // javascript callback for the 'drained' signal
    }

This signal is emitted once decodebin has finished decoding all the data.

Parameters:

`bin` –

The decodebin

`udata` –
No description available

Flags: Run Last

### unknown-type

    unknown_type_callback (GstElement * bin,
                           GstPad * pad,
                           GstCaps * caps,
                           gpointer udata)

    def unknown_type_callback (bin, pad, caps, udata):
        #python callback for the 'unknown-type' signal

    function unknown_type_callback(bin: GstElement * bin, pad: GstPad * pad, caps: GstCaps * caps, udata: gpointer udata): {
        // javascript callback for the 'unknown-type' signal
    }

This signal is emitted when a pad for which there is no further possible decoding is added to the decodebin.

Parameters:

`bin` –

The decodebin.

`pad` –

The new pad containing caps that cannot be resolved to a 'final' stream type.

`caps` –

The GstCaps of the pad that cannot be resolved.

`udata` –
No description available

Flags: Run Last

## Properties

### caps

    “caps” GstCaps *

The caps on which to stop decoding.

Flags : Read / Write

Default value :

    video/x-raw(ANY); audio/x-raw(ANY); text/x-raw(ANY); subpicture/x-dvd; subpicture/x-dvb; subpicture/x-xsub; subpicture/x-pgs; closedcaption/x-cea-608; closedcaption/x-cea-708; application/x-onvif-metadata; meta/x-klv; meta/x-id3; meta/x-st-2038

### connection-speed

    “connection-speed” guint64

Network connection speed in kbps (0 = unknown)

Flags : Read / Write

Default value : 0

### expose-all-streams

    “expose-all-streams” gboolean

Expose all streams, including those of unknown type or that don't match the 'caps' property

Flags : Read / Write

Default value : true

### force-sw-decoders

    “force-sw-decoders” gboolean

Use only sofware decoders to process streams

Flags : Read / Write

Default value : false

### high-percent

    “high-percent” gint

High threshold percent for buffering to finish.

Flags : Read / Write

Default value : 99

### low-percent

    “low-percent” gint

Low threshold percent for buffering to start.

Flags : Read / Write

Default value : 10

### max-size-buffers

    “max-size-buffers” guint

Max amount of buffers in the queue (0=automatic).

Flags : Read / Write

Default value : 0

### max-size-bytes

    “max-size-bytes” guint

Max amount of bytes in the queue (0=automatic).

Flags : Read / Write

Default value : 0

### max-size-time

    “max-size-time” guint64

Max amount of time in the queue (in ns, 0=automatic).

Flags : Read / Write

Default value : 0

### post-stream-topology

    “post-stream-topology” gboolean

Post stream-topology messages

Flags : Read / Write

Default value : false

### sink-caps

    “sink-caps” GstCaps *

The caps of the input data. (NULL = use typefind element)

Flags : Read / Write

Default value :

    EMPTY

### subtitle-encoding

    “subtitle-encoding” gchararray

Encoding to assume if input subtitles are not in UTF-8 encoding. If not set, the GST_SUBTITLE_ENCODING environment variable will be checked for an encoding to use. If that is not set either, ISO-8859-15 will be assumed.

Flags : Read / Write

Default value : NULL

### use-buffering

    “use-buffering” gboolean

Emit GST_MESSAGE_BUFFERING based on low-/high-percent thresholds

Flags : Read / Write

Default value : false

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