diff options
Diffstat (limited to 'libAACenc/include')
| -rw-r--r-- | libAACenc/include/aacenc_lib.h | 194 |
1 files changed, 149 insertions, 45 deletions
diff --git a/libAACenc/include/aacenc_lib.h b/libAACenc/include/aacenc_lib.h index 862dcb5..8c0e1cd 100644 --- a/libAACenc/include/aacenc_lib.h +++ b/libAACenc/include/aacenc_lib.h @@ -2,7 +2,7 @@ /* ----------------------------------------------------------------------------------------------------------- Software License for The Fraunhofer FDK AAC Codec Library for Android -© Copyright 1995 - 2012 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. +© Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. All rights reserved. 1. INTRODUCTION @@ -316,7 +316,8 @@ if the parameter was not set from extern. The bitrate depends on the number of e channels and sampling rate and is determined as follows. \code AAC-LC (AOT_AAC_LC): 1.5 bits per sample -HE-AAC (AOT_SBR): 0.625 bits per sample +HE-AAC (AOT_SBR): 0.625 bits per sample (dualrate sbr) +HE-AAC (AOT_SBR): 1.125 bits per sample (downsampled sbr) HE-AAC v2 (AOT_PS): 0.5 bits per sample \endcode @@ -341,6 +342,33 @@ increase which might be significant. If workload is not an issue in the applicat we recommended to activate this feature. \code aacEncoder_SetParam(hAacEncoder, AACENC_AFTERBURNER, 1); \endcode +\subsection encELD ELD Auto Configuration Mode +For ELD configuration a so called auto configurator is available which configures SBR and the SBR ratio by itself. +The configurator is used when the encoder parameter ::AACENC_SBR_MODE and ::AACENC_SBR_RATIO are not set explicitely. + +Based on sampling rate and chosen bitrate per channel a reasonable SBR configuration will be used. +\verbatim +------------------------------------------------------------ + Sampling Rate | Channel Bitrate | SBR | SBR Ratio +-----------------+-----------------+------+----------------- + ]min, 16] kHz | min - 27999 | on | downsampled SBR + | 28000 - max | off | --- +-----------------+-----------------+------+----------------- + ]16 - 24] kHz | min - 39999 | on | downsampled SBR + | 40000 - max | off | --- +-----------------+-----------------+------+----------------- + ]24 - 32] kHz | min - 27999 | on | dualrate SBR + | 28000 - 55999 | on | downsampled SBR + | 56000 - max | off | --- +-----------------+-----------------+------+----------------- + ]32 - 44.1] kHz | min - 63999 | on | dualrate SBR + | 64000 - max | off | --- +-----------------+-----------------+------+----------------- + ]44.1 - 48] kHz | min - 63999 | on | dualrate SBR + | 64000 - max | off | --- +------------------------------------------------------------ +\endverbatim + \section audiochCfg Audio Channel Configuration The MPEG standard refers often to the so-called Channel Configuration. This Channel Configuration is used for a fixed Channel @@ -349,16 +377,20 @@ For user defined Configurations the Channel Configuration is set to 0 and the Ch Program Config Element. The present Encoder implementation does not allow the user to configure this Channel Configuration from extern. The Encoder implementation supports fixed Channel Modes which are mapped to Channel Configuration as follow. \verbatim --------------------------------------------------------------------- - ChannelMode | ChCfg | front_El | side_El | back_El | lfe_El ------------------+--------+----------+----------+----------+-------- -MODE_1 | 1 | SCE | | | -MODE_2 | 2 | CPE | | | -MODE_1_2 | 3 | SCE, CPE | | | -MODE_1_2_1 | 4 | SCE, CPE | | SCE | -MODE_1_2_2 | 5 | SCE, CPE | | CPE | -MODE_1_2_2_1 | 6 | SCE, CPE | | CPE | LFE --------------------------------------------------------------------- +------------------------------------------------------------------------------- + ChannelMode | ChCfg | front_El | side_El | back_El | lfe_El +-----------------------+--------+---------------+----------+----------+-------- +MODE_1 | 1 | SCE | | | +MODE_2 | 2 | CPE | | | +MODE_1_2 | 3 | SCE, CPE | | | +MODE_1_2_1 | 4 | SCE, CPE | | SCE | +MODE_1_2_2 | 5 | SCE, CPE | | CPE | +MODE_1_2_2_1 | 6 | SCE, CPE | | CPE | LFE +MODE_1_2_2_2_1 | 7 | SCE, CPE, CPE | | CPE | LFE +-----------------------+--------+---------------+----------+----------+-------- +MODE_7_1_REAR_SURROUND | 0 | SCE, CPE | | CPE, CPE | LFE +MODE_7_1_FRONT_CENTER | 0 | SCE, CPE, CPE | | CPE | LFE +------------------------------------------------------------------------------- - SCE: Single Channel Element. - CPE: Channel Pair. - SCE: Low Frequency Element. @@ -374,16 +406,20 @@ Beside the Channel Element assignment the Channel Modes are resposible for audio of the audio data depends on the selected ::AACENC_CHANNELORDER which can be MPEG or WAV like order.\n Following Table describes the complete channel mapping for both Channel Order configurations. \verbatim ---------------------------------------------------------------------------------- -ChannelMode | MPEG-Channelorder | WAV-Channelorder ------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+--- -MODE_1 | 0 | | | | | | | | 0 | | | | | | | -MODE_2 | 0 | 1 | | | | | | | 0 | 1 | | | | | | -MODE_1_2 | 0 | 1 | 2 | | | | | | 2 | 0 | 1 | | | | | -MODE_1_2_1 | 0 | 1 | 2 | 3 | | | | | 2 | 0 | 1 | 3 | | | | -MODE_1_2_2 | 0 | 1 | 2 | 3 | 4 | | | | 2 | 0 | 1 | 3 | 4 | | | -MODE_1_2_2_1 | 0 | 1 | 2 | 3 | 4 | 5 | | | 2 | 0 | 1 | 4 | 5 | 3 | | ---------------------------------------------------------------------------------- +--------------------------------------------------------------------------------------- +ChannelMode | MPEG-Channelorder | WAV-Channelorder +-----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+--- +MODE_1 | 0 | | | | | | | | 0 | | | | | | | +MODE_2 | 0 | 1 | | | | | | | 0 | 1 | | | | | | +MODE_1_2 | 0 | 1 | 2 | | | | | | 2 | 0 | 1 | | | | | +MODE_1_2_1 | 0 | 1 | 2 | 3 | | | | | 2 | 0 | 1 | 3 | | | | +MODE_1_2_2 | 0 | 1 | 2 | 3 | 4 | | | | 2 | 0 | 1 | 3 | 4 | | | +MODE_1_2_2_1 | 0 | 1 | 2 | 3 | 4 | 5 | | | 2 | 0 | 1 | 4 | 5 | 3 | | +MODE_1_2_2_2_1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 2 | 6 | 7 | 0 | 1 | 4 | 5 | 3 +-----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+--- +MODE_7_1_REAR_SURROUND | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 2 | 0 | 1 | 6 | 7 | 4 | 5 | 3 +MODE_7_1_FRONT_CENTER | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 2 | 6 | 7 | 0 | 1 | 4 | 5 | 3 +--------------------------------------------------------------------------------------- \endverbatim The denoted mapping is important for correct audio channel assignment when using MPEG or WAV ordering. The incoming audio @@ -416,8 +452,9 @@ determines the maximum allowed bitrate for AAC-LC. For HE-AAC and HE-AAC v2 a li look-up table is used. A good working point in terms of audio quality, sampling rate and bitrate, is at 1 to 1.5 -bits/audio sample for AAC-LC, 0.625 bits/audio sample for HE-AAC and 0.5 bits/audio sample -for HE-AAC v2. For example for one channel with a sampling frequency of 48 kHz, the range from +bits/audio sample for AAC-LC, 0.625 bits/audio sample for dualrate HE-AAC, 1.125 bits/audio sample +for downsampled HE-AAC and 0.5 bits/audio sample for HE-AAC v2. +For example for one channel with a sampling frequency of 48 kHz, the range from 48 kbit/s to 72 kbit/s achieves reasonable audio quality for AAC-LC. For HE-AAC and HE-AAC v2 the lowest possible audio input sampling frequency is 16 kHz because then the @@ -434,7 +471,7 @@ quality at that bitrate than HE-AAC or HE-AAC v2. The following table provides an overview of recommended encoder configuration parameters which we determined by virtue of numerous listening tests. -\subsection reommendedConfigLC AAC-LC, HE-AAC, HE-AACv2. +\subsection reommendedConfigLC AAC-LC, HE-AAC, HE-AACv2 in Dualrate SBR mode. \verbatim ----------------------------------------------------------------------------------- Audio Object Type | Bit Rate Range | Supported | Preferred | No. of @@ -457,8 +494,8 @@ AAC LC + SBR | 64000 - 128000 | 32.00, 44.10, 48.00 | 48.00 | -------------------+------------------+-----------------------+------------+------- AAC LC + SBR | 64000 - 69999 | 32.00, 44.10, 48.00 | 32.00 | 5, 5.1 AAC LC + SBR | 70000 - 159999 | 32.00, 44.10, 48.00 | 44.10 | 5, 5.1 -AAC LC + SBR | 160000 - 319999 | 32.00, 44.10, 48.00 | 48.00 | 5, 5.1 -AAC LC + SBR | 320000 - 640000 | 64.00, 88.20, 96.00 | 96.00 | 5, 5.1 +AAC LC + SBR | 160000 - 245999 | 32.00, 44.10, 48.00 | 48.00 | 5 +AAC LC + SBR | 160000 - 265999 | 32.00, 44.10, 48.00 | 48.00 | 5.1 -------------------+------------------+-----------------------+------------+------- AAC LC | 8000 - 15999 | 11.025, 12.00, 16.00 | 12.00 | 1 AAC LC | 16000 - 23999 | 16.00 | 16.00 | 1 @@ -481,7 +518,7 @@ AAC LC | 280000 - 800000 | 32.00, 44.10, 48.00 | 44.10 | 5, ----------------------------------------------------------------------------------- \endverbatim \n -\subsection reommendedConfigLD AAC-LD, AAC-ELD, AAC-ELD with SBR. +\subsection reommendedConfigLD AAC-LD, AAC-ELD, AAC-ELD with SBR in Dualrate SBR mode. \verbatim ----------------------------------------------------------------------------------- Audio Object Type | Bit Rate Range | Supported | Preferred | No. of @@ -489,18 +526,20 @@ Audio Object Type | Bit Rate Range | Supported | Preferred | No. | | [kHz] | Rate | | | | [kHz] | -------------------+------------------+-----------------------+------------+------- -ELD + SBR | 16000 - 24999 | 32.00 - 44.10 | 32.00 | 1 +ELD + SBR | 18000 - 24999 | 32.00 - 44.10 | 32.00 | 1 ELD + SBR | 25000 - 31999 | 32.00 - 48.00 | 32.00 | 1 ELD + SBR | 32000 - 64000 | 32.00 - 48.00 | 48.00 | 1 -------------------+------------------+-----------------------+------------+------- ELD + SBR | 32000 - 51999 | 32.00 - 48.00 | 44.10 | 2 ELD + SBR | 52000 - 128000 | 32.00 - 48.00 | 48.00 | 2 -------------------+------------------+-----------------------+------------+------- -ELD + SBR | 72000 - 192000 | 44.10 - 48.00 | 48.00 | 3 +ELD + SBR | 72000 - 160000 | 44.10 - 48.00 | 48.00 | 3 +-------------------+------------------+-----------------------+------------+------- +ELD + SBR | 96000 - 212000 | 44.10 - 48.00 | 48.00 | 4 -------------------+------------------+-----------------------+------------+------- -ELD + SBR | 96000 - 256000 | 44.10 - 48.00 | 48.00 | 4 +ELD + SBR | 120000 - 246000 | 44.10 - 48.00 | 48.00 | 5 -------------------+------------------+-----------------------+------------+------- -ELD + SBR | 120000 - 320000 | 44.10 - 48.00 | 48.00 | 5 +ELD + SBR | 120000 - 266000 | 44.10 - 48.00 | 48.00 | 5.1 -------------------+------------------+-----------------------+------------+------- LD, ELD | 16000 - 19999 | 16.00 - 24.00 | 16.00 | 1 LD, ELD | 20000 - 39999 | 16.00 - 32.00 | 24.00 | 1 @@ -531,13 +570,33 @@ LD, ELD | 340000 - 960000 | 44.10 - 48.00 | 48.00 | ----------------------------------------------------------------------------------- \endverbatim \n +\subsection reommendedConfigELD AAC-ELD with SBR in Downsampled SBR mode. +\verbatim +----------------------------------------------------------------------------------- +Audio Object Type | Bit Rate Range | Supported | Preferred | No. of + | [bit/s] | Sampling Rates | Sampl. | Chan. + | | [kHz] | Rate | + | | | [kHz] | +-------------------+------------------+-----------------------+------------+------- +ELD + SBR | 18000 - 24999 | 16.00 - 22.05 | 22.05 | 1 +(downsampled SBR) | 25000 - 35999 | 22.05 - 32.00 | 24.00 | 1 + | 36000 - 64000 | 32.00 - 48.00 | 32.00 | 1 +----------------------------------------------------------------------------------- +\endverbatim \n + + \page ENCODERBEHAVIOUR Encoder Behaviour \section BEHAVIOUR_BANDWIDTH Bandwidth The FDK AAC encoder usually does not use the full frequency range of the input signal, but restricts the bandwidth according to certain library-internal settings. They can be changed in the table "bandWidthTable" in the -file bandwidth.cpp (if available), or via command-line argument "-w" (see chapter \ref CommandLineUsage). +file bandwidth.cpp (if available). + +The encoder API provides the ::AACENC_BANDWIDTH parameter to adjust the bandwidth explicitly. +\code +aacEncoder_SetParam(hAacEncoder, AACENC_BANDWIDTH, value); +\endcode However it is not recommended to change these settings, because they are based on numerious listening tests and careful tweaks to ensure the best overall encoding quality. @@ -638,7 +697,6 @@ an MPEG-2 AOT is choosen since PNS is an MPEG-4 AAC feature. If SBR is activated, the encoder automatically deactivates PNS internally. If TNS is disabled but PNS is allowed, the encoder deactivates PNS calculation internally. - */ #ifndef _AAC_ENC_LIB_H_ @@ -858,8 +916,9 @@ typedef enum AACENC_SAMPLERATE = 0x0103, /*!< Audio input data sampling rate. Encoder supports following sampling rates: 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000, 64000, 88200, 96000 */ - AACENC_SBR_MODE = 0x0104, /*!< Configure SBR independently of the chosen Audio Object Type ::AUDIO_OBJECT_TYPE:. - This parameter is only available for ELD. + AACENC_SBR_MODE = 0x0104, /*!< 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. */ @@ -869,12 +928,21 @@ typedef enum - 480: Optional length in LD/ELD configuration. */ AACENC_CHANNELMODE = 0x0106, /*!< Set explicit channel mode. Channel mode must match with number of input channels. - - 1-6: MPEG channel modes supported, see ::CHANNEL_MODE in FDK_audio.h. */ + - 1-7 and 33,34: MPEG channel modes supported, see ::CHANNEL_MODE in FDK_audio.h. */ AACENC_CHANNELORDER = 0x0107, /*!< Input audio data channel ordering scheme: - 0: MPEG channel ordering (e. g. 5.1: C, L, R, SL, SR, LFE). (default) - 1: WAVE file format channel ordering (e. g. 5.1: L, R, C, LFE, SL, SR). */ + AACENC_SBR_RATIO = 0x0108, /*!< Controls activation of downsampled SBR. With downsampled SBR, the delay will be + shorter. On the other hand, for achieving the same quality level, downsampled SBR + needs more bits than dual-rate SBR. + With downsampled SBR, the AAC encoder will work at the same sampling rate as the + SBR encoder (single rate). + Downsampled SBR is supported for AAC-ELD and HE-AACv1. + - 1: Downsampled SBR (default for ELD). + - 2: Dual-rate SBR (default for HE-AAC). */ + AACENC_AFTERBURNER = 0x0200, /*!< 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 @@ -906,14 +974,50 @@ typedef enum - n: Frame count period. */ AACENC_SIGNALING_MODE = 0x0302, /*!< Signaling mode of the extension AOT: - - 0: Implicit backward compatible signaling. (default) - - 1: Explicit SBR and implicit PS signaling. - - 2: Explicit hierarchical signaling. - - The use of backward-compatible implicit signaling is recommended if the user specically - aims at preserving compatibility with decoders only capable of decoding AAC-LC. Otherwise - use non-backward-compatible explicit signaling. - Bitstream formats ADTS and ADIF can only do implicit signaling. */ + - 0: Implicit backward compatible signaling (default for non-MPEG-4 based + AOT's and for the transport formats ADIF and ADTS) + - A stream that uses implicit signaling can be decoded by every AAC decoder, even AAC-LC-only decoders + - An AAC-LC-only decoder will only decode the low-frequency part of the stream, resulting in a band-limited output + - This method works with all transport formats + - This method does not work with downsampled SBR + - 1: Explicit backward compatible signaling + - A stream that uses explicit backward compatible signaling can be decoded by every AAC decoder, even AAC-LC-only decoders + - An AAC-LC-only decoder will only decode the low-frequency part of the stream, resulting in a band-limited output + - A decoder not capable of decoding PS will only decode the AAC-LC+SBR part. + If the stream contained PS, the result will be a a decoded mono downmix + - This method does not work with ADIF or ADTS. For LOAS/LATM, it only works with AudioMuxVersion==1 + - This method does work with downsampled SBR + - 2: Explicit hierarchical signaling (default for MPEG-4 based AOT's and for all transport formats excluding ADIF and ADTS) + - A stream that uses explicit hierarchical signaling can be decoded only by HE-AAC decoders + - An AAC-LC-only decoder will not decode a stream that uses explicit hierarchical signaling + - A decoder not capable of decoding PS will not decode the stream at all if it contained PS + - This method does not work with ADIF or ADTS. It works with LOAS/LATM and the MPEG-4 File format + - This method does work with downsampled SBR + + For making sure that the listener always experiences the best audio quality, + explicit hierarchical signaling should be used. + This makes sure that only a full HE-AAC-capable decoder will decode those streams. + The audio is played at full bandwidth. + For best backwards compatibility, it is recommended to encode with implicit SBR signaling. + A decoder capable of AAC-LC only will then only decode the AAC part, which means the decoded + audio will sound band-limited. + + For MPEG-2 transport types (ADTS,ADIF), only implicit signaling is possible. + + For LOAS and LATM, explicit backwards compatible signaling only works together with AudioMuxVersion==1. + The reason is that, for explicit backwards compatible signaling, additional information will be appended to the ASC. + A decoder that is only capable of decoding AAC-LC will skip this part. + Nevertheless, for jumping to the end of the ASC, it needs to know the ASC length. + Transmitting the length of the ASC is a feature of AudioMuxVersion==1, it is not possible to transmit the + length of the ASC with AudioMuxVersion==0, therefore an AAC-LC-only decoder will not be able to parse a + LOAS/LATM stream that was being encoded with AudioMuxVersion==0. + + For downsampled SBR, explicit signaling is mandatory. The reason for this is that the + extension sampling frequency (which is in case of SBR the sampling frequqncy of the SBR part) + can only be signaled in explicit mode. + + For AAC-ELD, the SBR information is transmitted in the ELDSpecific Config, which is part of the + AudioSpecificConfig. Therefore, the settings here will have no effect on AAC-ELD.*/ AACENC_TPSUBFRAMES = 0x0303, /*!< Number of sub frames in a transport frame for LOAS/LATM or ADTS (default 1). - ADTS: Maximum number of sub frames restricted to 4. |