AACEncoderFDK Class Reference

Encodes PCM data to the AAC format and writes the result to a stream This is basically just a wrapper using https://github.com/pschatzmann/arduino-fdk-aac. More...

#include <CodecAACFDK.h>

Inheritance diagram for AACEncoderFDK:

Public Member Functions
	AACEncoderFDK (Print &out_stream)
AudioInfo	audioInfo ()
	provides the actual input AudioInfo
virtual AudioInfo	audioInfoOut ()
	provides the actual output AudioInfo: this is usually the same as audioInfo() unless we use a transforming stream
bool	begin ()
virtual bool	begin (AudioInfo info)
	Opens the encoder More...
virtual bool	begin (int input_channels=2, int input_sample_rate=44100, int input_bits_per_sample=16)
	Opens the encoder More...
aac_fdk::AACEncoderFDK *	driver ()
void	end ()
UINT	getParameter (const AACENC_PARAM param)
const char *	mime ()
	Provides the mime type of the encoded result.
	operator bool ()
virtual void	setAfterburner (bool afterburner)
	This parameter controls the use of the afterburner feature. The afterburner is a type of analysis by synthesis algorithm which increases the audio quality but also the required processing power. It is recommended to always activate this if additional memory consumption and processing power consumption is not a problem. If increased MHz and memory consumption are an issue then the MHz and memory cost of this optional module need to be evaluated against the improvement in audio quality on a case by case basis. More...
void	setAudioInfo (AudioInfo from) override
	Defines the Audio Info.
virtual void	setAudioObjectType (int aot)
	Audio object type. See ::AUDIO_OBJECT_TYPE in FDK_audio.h. More...
virtual void	setBitrate (int bitrate)
	Total encoder bitrate. This parameter is mandatory and interacts with ::AACENC_BITRATEMODE. More...
void	setOutput (Print &out_stream)
	Defines the output.
virtual void	setOutputBufferSize (int outbuf_size)
	Set the Output Buffer Size object. More...
int	setParameter (AACENC_PARAM param, uint32_t value)
virtual void	setSpectralBandReplication (int eld_sbr)
	Configure SBR independently of the chosen Audio Object Type ::AUDIO_OBJECT_TYPE. This parameter is for ELD audio object type only. More...
virtual void	setVariableBitrateMode (int vbr)
	Bitrate mode. Configuration can be different kind of bitrate configurations: More...
size_t	write (const uint8_t *data, size_t len)

Protected Member Functions
void	writeBlocking (Print *out, uint8_t *data, size_t len)

Protected Attributes
aac_fdk::AACEncoderFDK *	enc =nullptr
AudioInfo	info

Detailed Description

Encodes PCM data to the AAC format and writes the result to a stream This is basically just a wrapper using https://github.com/pschatzmann/arduino-fdk-aac.

Author

Phil Schatzmann

Copyright

GPLv3

Member Function Documentation

begin() [1/2]

virtual bool begin ( AudioInfo  info )

inlinevirtual

Opens the encoder

Parameters

info

Returns

int

Reimplemented from AudioWriter.

begin() [2/2]

virtual bool begin ( int  input_channels = 2, int  input_sample_rate = 44100, int  input_bits_per_sample = 16  )

inlinevirtual

Opens the encoder

Parameters

input_channels
input_sample_rate
input_bits_per_sample

Returns

int 0 => ok; error with negative number

setAfterburner()

virtual void setAfterburner ( bool  afterburner )

inlinevirtual

This parameter controls the use of the afterburner feature. The afterburner is a type of analysis by synthesis algorithm which increases the audio quality but also the required processing power. It is recommended to always activate this if additional memory consumption and processing power consumption is not a problem. If increased MHz and memory consumption are an issue then the MHz and memory cost of this optional module need to be evaluated against the improvement in audio quality on a case by case basis.

• 0: Disable afterburner (default).
• 1: Enable afterburner.

setAudioObjectType()

virtual void setAudioObjectType ( int  aot )

inlinevirtual

Audio object type. See ::AUDIO_OBJECT_TYPE in FDK_audio.h.

• 2: MPEG-4 AAC Low Complexity.
• 5: MPEG-4 AAC Low Complexity with Spectral Band Replication (HE-AAC).
• 29: MPEG-4 AAC Low Complexity with Spectral Band Replication and Parametric Stereo (HE-AAC v2). This configuration can be used only with stereo input audio data.
• 23: MPEG-4 AAC Low-Delay.
• 39: MPEG-4 AAC Enhanced Low-Delay. Since there is no ::AUDIO_OBJECT_TYPE for ELD in combination with SBR defined, enable SBR explicitely by ::AACENC_SBR_MODE parameter. The ELD v2 212 configuration can be configured by ::AACENC_CHANNELMODE parameter.
• 129: MPEG-2 AAC Low Complexity.
• 132: MPEG-2 AAC Low Complexity with Spectral Band Replication (HE-AAC).

Please note that the virtual MPEG-2 AOT's basically disables non-existing Perceptual Noise Substitution tool in AAC encoder and controls the MPEG_ID flag in adts header. The virtual MPEG-2 AOT doesn't prohibit specific transport formats.

setBitrate()

virtual void setBitrate ( int  bitrate )

inlinevirtual

Total encoder bitrate. This parameter is
mandatory and interacts with ::AACENC_BITRATEMODE.

• CBR: Bitrate in bits/second.
• VBR: Variable bitrate. Bitrate argument will be ignored. See suppBitrates for details.

setOutputBufferSize()

virtual void setOutputBufferSize ( int  outbuf_size )

inlinevirtual

Set the Output Buffer Size object.

Parameters

outbuf_size

setSpectralBandReplication()

virtual void setSpectralBandReplication ( int  eld_sbr )

inlinevirtual

Configure SBR independently of the chosen Audio Object Type ::AUDIO_OBJECT_TYPE. This parameter is for ELD audio object type only.

• -1: Use ELD SBR auto configurator (default).
• 0: Disable Spectral Band Replication.
• 1: Enable Spectral Band Replication.

setVariableBitrateMode()

virtual void setVariableBitrateMode ( int  vbr )

inlinevirtual

Bitrate mode. Configuration can be different kind of bitrate configurations:

• 0: Constant bitrate, use bitrate according to ::AACENC_BITRATE. (default) Within none LD/ELD ::AUDIO_OBJECT_TYPE, the CBR mode makes use of full allowed bitreservoir. In contrast, at Low-Delay ::AUDIO_OBJECT_TYPE the bitreservoir is kept very small.
• 1: Variable bitrate mode, very low bitrate.
• 2: Variable bitrate mode, low bitrate.
• 3: Variable bitrate mode, medium bitrate.
• 4: Variable bitrate mode, high bitrate.
• 5: Variable bitrate mode, very high bitrate.

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The documentation for this class was generated from the following file:

• src/AudioTools/AudioCodecs/CodecAACFDK.h