gi-gstaudio-1.0.19: GStreamerAudio bindings

CopyrightWill Thompson Iñaki García Etxebarria and Jonas Platte
LicenseLGPL-2.1
MaintainerIñaki García Etxebarria (inaki@blueleaf.cc)
Safe HaskellNone
LanguageHaskell2010

GI.GstAudio.Objects.AudioDecoder

Contents

Description

This base class is for audio decoders turning encoded data into raw audio samples.

GstAudioDecoder and subclass should cooperate as follows.

Configuration

  • Initially, GstAudioDecoder calls start when the decoder element is activated, which allows subclass to perform any global setup. Base class (context) parameters can already be set according to subclass capabilities (or possibly upon receive more information in subsequent setFormat).
  • GstAudioDecoder calls setFormat to inform subclass of the format of input audio data that it is about to receive. While unlikely, it might be called more than once, if changing input parameters require reconfiguration.
  • GstAudioDecoder calls stop at end of all processing.

As of configuration stage, and throughout processing, GstAudioDecoder provides various (context) parameters, e.g. describing the format of output audio data (valid when output caps have been set) or current parsing state. Conversely, subclass can and should configure context to inform base class of its expectation w.r.t. buffer handling.

Data processing

  • Base class gathers input data, and optionally allows subclass to parse this into subsequently manageable (as defined by subclass) chunks. Such chunks are subsequently referred to as 'frames', though they may or may not correspond to 1 (or more) audio format frame.
  • Input frame is provided to subclass' handleFrame.
  • If codec processing results in decoded data, subclass should call gstAudioDecoderFinishFrame to have decoded data pushed downstream.
  • Just prior to actually pushing a buffer downstream, it is passed to prePush. Subclass should either use this callback to arrange for additional downstream pushing or otherwise ensure such custom pushing occurs after at least a method call has finished since setting src pad caps.
  • During the parsing process GstAudioDecoderClass will handle both srcpad and sinkpad events. Sink events will be passed to subclass if event callback has been provided.

Shutdown phase

  • GstAudioDecoder class calls stop to inform the subclass that data parsing will be stopped.

Subclass is responsible for providing pad template caps for source and sink pads. The pads need to be named "sink" and "src". It also needs to set the fixed caps on srcpad, when the format is ensured. This is typically when base class calls subclass' setFormat function, though it might be delayed until calling gstAudioDecoderFinishFrame.

In summary, above process should have subclass concentrating on codec data processing while leaving other matters to base class, such as most notably timestamp handling. While it may exert more control in this area (see e.g. prePush), it is very much not recommended.

In particular, base class will try to arrange for perfect output timestamps as much as possible while tracking upstream timestamps. To this end, if deviation between the next ideal expected perfect timestamp and upstream exceeds AudioDecoder:tolerance, then resync to upstream occurs (which would happen always if the tolerance mechanism is disabled).

In non-live pipelines, baseclass can also (configurably) arrange for output buffer aggregation which may help to redue large(r) numbers of small(er) buffers being pushed and processed downstream. Note that this feature is only available if the buffer layout is interleaved. For planar buffers, the decoder implementation is fully responsible for the output buffer size.

On the other hand, it should be noted that baseclass only provides limited seeking support (upon explicit subclass request), as full-fledged support should rather be left to upstream demuxer, parser or alike. This simple approach caters for seeking and duration reporting using estimated input bitrates.

Things that subclass need to take care of:

  • Provide pad templates
  • Set source pad caps when appropriate
  • Set user-configurable properties to sane defaults for format and implementing codec at hand, and convey some subclass capabilities and expectations in context.
  • Accept data in handleFrame and provide encoded results to gstAudioDecoderFinishFrame. If it is prepared to perform PLC, it should also accept NULL data in handleFrame and provide for data for indicated duration.
Synopsis

Exported types

newtype AudioDecoder Source #

Memory-managed wrapper type.

Constructors

AudioDecoder (ManagedPtr AudioDecoder) 
Instances
GObject AudioDecoder Source # 
Instance details

Defined in GI.GstAudio.Objects.AudioDecoder

Methods

gobjectType :: IO GType

HasParentTypes AudioDecoder Source # 
Instance details

Defined in GI.GstAudio.Objects.AudioDecoder

type ParentTypes AudioDecoder Source # 
Instance details

Defined in GI.GstAudio.Objects.AudioDecoder

type ParentTypes AudioDecoder = Element ': (Object ': (Object ': ([] :: [Type])))

class (GObject o, IsDescendantOf AudioDecoder o) => IsAudioDecoder o Source #

Type class for types which can be safely cast to AudioDecoder, for instance with toAudioDecoder.

Instances
(GObject o, IsDescendantOf AudioDecoder o) => IsAudioDecoder o Source # 
Instance details

Defined in GI.GstAudio.Objects.AudioDecoder

toAudioDecoder :: (MonadIO m, IsAudioDecoder o) => o -> m AudioDecoder Source #

Cast to AudioDecoder, for types for which this is known to be safe. For general casts, use castTo.

Methods

allocateOutputBuffer

audioDecoderAllocateOutputBuffer Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Word64

size: size of the buffer

-> m Buffer

Returns: allocated buffer

Helper function that allocates a buffer to hold an audio frame for dec's current output format.

finishFrame

audioDecoderFinishFrame Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Buffer

buf: decoded data

-> Int32

frames: number of decoded frames represented by decoded data

-> m FlowReturn

Returns: a FlowReturn that should be escalated to caller (of caller)

Collects decoded data and pushes it downstream.

buf may be NULL in which case the indicated number of frames are discarded and considered to have produced no output (e.g. lead-in or setup frames). Otherwise, source pad caps must be set when it is called with valid data in buf.

Note that a frame received in AudioDecoderClass.handle_frame() may be invalidated by a call to this function.

finishSubframe

audioDecoderFinishSubframe Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Buffer

buf: decoded data

-> m FlowReturn

Returns: a FlowReturn that should be escalated to caller (of caller)

Collects decoded data and pushes it downstream. This function may be called multiple times for a given input frame.

buf may be NULL in which case it is assumed that the current input frame is finished. This is equivalent to calling audioDecoderFinishSubframe with a NULL buffer and frames=1 after having pushed out all decoded audio subframes using this function.

When called with valid data in buf the source pad caps must have been set already.

Note that a frame received in AudioDecoderClass.handle_frame() may be invalidated by a call to this function.

Since: 1.16

getAllocator

audioDecoderGetAllocator Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m (Allocator, AllocationParams) 

Lets AudioDecoder sub-classes to know the memory allocator used by the base class and its params.

Unref the allocator after use it.

getAudioInfo

audioDecoderGetAudioInfo Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m AudioInfo

Returns: a AudioInfo describing the input audio format

No description available in the introspection data.

getDelay

audioDecoderGetDelay Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Int32

Returns: currently configured decoder delay

No description available in the introspection data.

getDrainable

audioDecoderGetDrainable Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Bool

Returns: TRUE if drainable handling is enabled.

MT safe.

Queries decoder drain handling.

getEstimateRate

audioDecoderGetEstimateRate Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Int32

Returns: currently configured byte to time conversion setting

No description available in the introspection data.

getLatency

audioDecoderGetLatency Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m (Word64, Word64) 

Sets the variables pointed to by min and max to the currently configured latency.

getMaxErrors

audioDecoderGetMaxErrors Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Int32

Returns: currently configured decoder tolerated error count.

No description available in the introspection data.

getMinLatency

audioDecoderGetMinLatency Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Word64

Returns: aggregation latency.

MT safe.

Queries decoder's latency aggregation.

getNeedsFormat

audioDecoderGetNeedsFormat Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Bool

Returns: TRUE if required format handling is enabled.

MT safe.

Queries decoder required format handling.

getParseState

audioDecoderGetParseState Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m (Bool, Bool) 

Return current parsing (sync and eos) state.

getPlc

audioDecoderGetPlc Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Bool

Returns: TRUE if packet loss concealment is enabled.

MT safe.

Queries decoder packet loss concealment handling.

getPlcAware

audioDecoderGetPlcAware Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Int32

Returns: currently configured plc handling

No description available in the introspection data.

getTolerance

audioDecoderGetTolerance Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Word64

Returns: decoder audio jitter tolerance threshold.

MT safe.

Queries current audio jitter tolerance threshold.

mergeTags

audioDecoderMergeTags Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Maybe TagList

tags: a TagList to merge, or NULL

-> TagMergeMode

mode: the TagMergeMode to use, usually GST_TAG_MERGE_REPLACE

-> m () 

Sets the audio decoder tags and how they should be merged with any upstream stream tags. This will override any tags previously-set with audioDecoderMergeTags.

Note that this is provided for convenience, and the subclass is not required to use this and can still do tag handling on its own.

negotiate

audioDecoderNegotiate Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> m Bool

Returns: True if the negotiation succeeded, else False.

Negotiate with downstream elements to currently configured AudioInfo. Unmark GST_PAD_FLAG_NEED_RECONFIGURE in any case. But mark it again if negotiate fails.

proxyGetcaps

audioDecoderProxyGetcaps Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

decoder: a AudioDecoder

-> Maybe Caps

caps: initial caps

-> Maybe Caps

filter: filter caps

-> m Caps

Returns: a Caps owned by caller

Returns caps that express caps (or sink template caps if caps == NULL) restricted to rate/channels/... combinations supported by downstream elements.

Since: 1.6

setAllocationCaps

audioDecoderSetAllocationCaps Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Maybe Caps

allocationCaps: a Caps or Nothing

-> m () 

Sets a caps in allocation query which are different from the set pad's caps. Use this function before calling audioDecoderNegotiate. Setting to Nothing the allocation query will use the caps from the pad.

Since: 1.10

setDrainable

audioDecoderSetDrainable Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Bool

enabled: new state

-> m () 

Configures decoder drain handling. If drainable, subclass might be handed a NULL buffer to have it return any leftover decoded data. Otherwise, it is not considered so capable and will only ever be passed real data.

MT safe.

setEstimateRate

audioDecoderSetEstimateRate Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Bool

enabled: whether to enable byte to time conversion

-> m () 

Allows baseclass to perform byte to time estimated conversion.

setLatency

audioDecoderSetLatency Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Word64

min: minimum latency

-> Word64

max: maximum latency

-> m () 

Sets decoder latency.

setMaxErrors

audioDecoderSetMaxErrors Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Int32

num: max tolerated errors

-> m () 

Sets numbers of tolerated decoder errors, where a tolerated one is then only warned about, but more than tolerated will lead to fatal error. You can set -1 for never returning fatal errors. Default is set to GST_AUDIO_DECODER_MAX_ERRORS.

setMinLatency

audioDecoderSetMinLatency Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Word64

num: new minimum latency

-> m () 

Sets decoder minimum aggregation latency.

MT safe.

setNeedsFormat

audioDecoderSetNeedsFormat Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Bool

enabled: new state

-> m () 

Configures decoder format needs. If enabled, subclass needs to be negotiated with format caps before it can process any data. It will then never be handed any data before it has been configured. Otherwise, it might be handed data without having been configured and is then expected being able to do so either by default or based on the input data.

MT safe.

setOutputCaps

audioDecoderSetOutputCaps Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Caps

caps: (fixed) Caps

-> m Bool

Returns: True on success.

Configure output caps on the srcpad of dec. Similar to audioDecoderSetOutputFormat, but allows subclasses to specify output caps that can't be expressed via AudioInfo e.g. caps that have caps features.

Since: 1.16

setOutputFormat

audioDecoderSetOutputFormat Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> AudioInfo

info: AudioInfo

-> m Bool

Returns: True on success.

Configure output info on the srcpad of dec.

setPlc

audioDecoderSetPlc Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Bool

enabled: new state

-> m () 

Enable or disable decoder packet loss concealment, provided subclass and codec are capable and allow handling plc.

MT safe.

setPlcAware

audioDecoderSetPlcAware Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Bool

plc: new plc state

-> m () 

Indicates whether or not subclass handles packet loss concealment (plc).

setTolerance

audioDecoderSetTolerance Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

dec: a AudioDecoder

-> Word64

tolerance: new tolerance

-> m () 

Configures decoder audio jitter tolerance threshold.

MT safe.

setUseDefaultPadAcceptcaps

audioDecoderSetUseDefaultPadAcceptcaps Source #

Arguments

:: (HasCallStack, MonadIO m, IsAudioDecoder a) 
=> a

decoder: a AudioDecoder

-> Bool

use: if the default pad accept-caps query handling should be used

-> m () 

Lets AudioDecoder sub-classes decide if they want the sink pad to use the default pad query handler to reply to accept-caps queries.

By setting this to true it is possible to further customize the default handler with GST_PAD_SET_ACCEPT_INTERSECT and GST_PAD_SET_ACCEPT_TEMPLATE

Since: 1.6

Properties

minLatency

No description available in the introspection data.

constructAudioDecoderMinLatency :: IsAudioDecoder o => Int64 -> IO (GValueConstruct o) Source #

Construct a GValueConstruct with valid value for the “min-latency” property. This is rarely needed directly, but it is used by new.

getAudioDecoderMinLatency :: (MonadIO m, IsAudioDecoder o) => o -> m Int64 Source #

Get the value of the “min-latency” property. When overloading is enabled, this is equivalent to

get audioDecoder #minLatency

setAudioDecoderMinLatency :: (MonadIO m, IsAudioDecoder o) => o -> Int64 -> m () Source #

Set the value of the “min-latency” property. When overloading is enabled, this is equivalent to

set audioDecoder [ #minLatency := value ]

plc

No description available in the introspection data.

constructAudioDecoderPlc :: IsAudioDecoder o => Bool -> IO (GValueConstruct o) Source #

Construct a GValueConstruct with valid value for the “plc” property. This is rarely needed directly, but it is used by new.

getAudioDecoderPlc :: (MonadIO m, IsAudioDecoder o) => o -> m Bool Source #

Get the value of the “plc” property. When overloading is enabled, this is equivalent to

get audioDecoder #plc

setAudioDecoderPlc :: (MonadIO m, IsAudioDecoder o) => o -> Bool -> m () Source #

Set the value of the “plc” property. When overloading is enabled, this is equivalent to

set audioDecoder [ #plc := value ]

tolerance

No description available in the introspection data.

constructAudioDecoderTolerance :: IsAudioDecoder o => Int64 -> IO (GValueConstruct o) Source #

Construct a GValueConstruct with valid value for the “tolerance” property. This is rarely needed directly, but it is used by new.

getAudioDecoderTolerance :: (MonadIO m, IsAudioDecoder o) => o -> m Int64 Source #

Get the value of the “tolerance” property. When overloading is enabled, this is equivalent to

get audioDecoder #tolerance

setAudioDecoderTolerance :: (MonadIO m, IsAudioDecoder o) => o -> Int64 -> m () Source #

Set the value of the “tolerance” property. When overloading is enabled, this is equivalent to

set audioDecoder [ #tolerance := value ]