Fraunhofer FDK AAC: Difference between revisions
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;-a <0,1>:Enable [[#Afterburner|''Afterburner'']]. 0=Disabled, 1=Enabled (recommended). Default is 1. | ;-a <0,1>:Enable [[#Afterburner|''Afterburner'']]. 0=Disabled, 1=Enabled (recommended). Default is 1. | ||
;-s <-1,0,1>:Spectral Band Replication (ELD AOT only). -1=Use ELD SBR auto configurator (default,recommended), 0=Disabled, 1=Enabled. Default is -1. | ;-s <-1,0,1>:Spectral Band Replication (ELD AOT only). -1=Use ELD SBR auto configurator (default,recommended), 0=Disabled, 1=Enabled. Default is -1. | ||
;-v <0-5>:[[#Bitrate modes|Bitrate mode]] Only 0-5 used. 0=CBR @ value given in -r. Default is 0. | ;-v <0-5>:[[#Bitrate modes|Bitrate mode]]. Only 0-5 used. 0=CBR @ value given in -r. Default is 0. | ||
=== ffmpeg === | === ffmpeg === | ||
libfdk-aac can be used with ffmpeg, but requires a custom build of ffmpeg. | libfdk-aac can be used with ffmpeg, but requires a custom build of ffmpeg. ffmpeg provides significant [https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_aac documentation for using libfdk_aac] in the ffmpeg wiki. | ||
CBR mode: | |||
ffmpeg -i <input> -c:a libfdk_aac -b:a 128k <output> | |||
VBR mode: | |||
ffmpeg -i <input> -c:a libfdk_aac -vbr 3 <output> | |||
;vbr:Values 1-5. See [[#Bitrate modes|Bitrate mode]]. | |||
=== avconv === | === avconv === | ||
libfdk-aac can be used with avconv, but requires a custom build of avconv. | libfdk-aac can be used with avconv, but requires a custom build of avconv with "--enable-libfdk-aac" passed to configure. | ||
CBR mode: | |||
avconv -i <input> -c:a libfdk_aac -b:a <bitrate> -afterburner 1 <output> | |||
VBR mode: | |||
aconv -i <input> -c:a libfdk_aac -flags +qscale -global_quality [1-5] -afterburner 1 <output> | |||
;afterburner:See ''[[#Afterburner|afterburner]]''. | |||
;global_quality:Values 1-5. See [[#Bitrate modes|Bitrate mode]]. | |||
== Links == | == Links == | ||
* [http://www.hydrogenaud.io/forums/index.php?showtopic=95989 Release information HydrogenAudio forums] | * [http://www.hydrogenaud.io/forums/index.php?showtopic=95989 Release information HydrogenAudio forums] | ||
* [http://sourceforge.net/p/opencore-amr/fdk-aac/ci/master/tree/ fdk-aac source code] | * [http://sourceforge.net/p/opencore-amr/fdk-aac/ci/master/tree/ fdk-aac source code] | ||
Revision as of 20:32, 24 July 2014
| Developer(s) | Fraunhofer IIS |
| Release information | |
|---|---|
| Stable release | |
| Compatibility | |
| Operating system | Android, Linux |
| Additional information | |
| Use | Encoder |
| License | Very liberal (NOTICE), but somehow considered non-free [1] |
| Website | Offical web page |
The Fraunhofer FDK AAC is a high-quality open-source AAC encoder library developed by Fraunhofer IIS. It was officially released for Android, but has been ported to other platforms.
MPEG-4 Audio Object Types
The library supports the following MPEG-4 AOTs:
| Object Type ID | Audio Object Type | Description |
|---|---|---|
| 2 | AAC-LC | "AAC Profile" MPEG-2 Low-complexity (LC) combined with MPEG-4 Perceptual Noise Substitution (PNS) |
| 5 | HE-AAC | AAC LC + SBR (Spectral Band Replication) |
| 29 | HE-AAC v2 | AAC LC + SBR + PS (Parametric Stereo) |
| 23 | AAC-LD | "Low Delay Profile" used for real-time communication |
| 39 | AAC-ELD | Enhanced Low Delay |
Afterburner
Afterburner is "a type of analysis by synthesis algorithm which increases the audio quality but also the required processing power." Fraunhofer recommends to always activate this feature.
Bitrate modes
| AACENC_BITRATEMODE | Bitrate | Comment |
|---|---|---|
| 0 | CBR @ AACENC_BITRATE | |
| 1 | VBR, about 32 kbps/channel | |
| 2 | VBR, about 40 kbps/channel | |
| 3 | VBR, about 48-56 kbps/channel | Max for HE and HEv2 |
| 4 | VBR, about 64 kbps/channel | |
| 5 | VBR, about 80-96 kbps/channel | |
| 6 | Fixed frame mode. | |
| 7 | Superframe mode. | |
| 8 | LD/ELD full bitreservoir for packet based transmission |
[lib]fdk-aac
The opencore-amr project maintains a source code distribution of the Fraunhofer library as fdk-aac, often packaged as libfdk-aac. It is distributed in a binary form in Debian (and Debian derivatives like Ubuntu) as libfdk-aac0.
The latest release is 0.1.3 (2013-11-25) [2].
aac-enc
fdk-aac includes a very, very basic command-line interface encoding utility, called aac-enc, that can encode to AAC from WAV.
Usage:
aac-enc [-r bitrate] [-t aot] [-a afterburner] [-s sbr] [-v vbr] in.wav out.aac
- -r <bitrate>
- CBR bitrate. Default is 64000.
- -t <aot>
- The Audio Object Type. Default is 2 (AAC-LC).
- -a <0,1>
- Enable Afterburner. 0=Disabled, 1=Enabled (recommended). Default is 1.
- -s <-1,0,1>
- Spectral Band Replication (ELD AOT only). -1=Use ELD SBR auto configurator (default,recommended), 0=Disabled, 1=Enabled. Default is -1.
- -v <0-5>
- Bitrate mode. Only 0-5 used. 0=CBR @ value given in -r. Default is 0.
ffmpeg
libfdk-aac can be used with ffmpeg, but requires a custom build of ffmpeg. ffmpeg provides significant documentation for using libfdk_aac in the ffmpeg wiki.
CBR mode:
ffmpeg -i <input> -c:a libfdk_aac -b:a 128k <output>
VBR mode:
ffmpeg -i <input> -c:a libfdk_aac -vbr 3 <output>
- vbr
- Values 1-5. See Bitrate mode.
avconv
libfdk-aac can be used with avconv, but requires a custom build of avconv with "--enable-libfdk-aac" passed to configure.
CBR mode:
avconv -i <input> -c:a libfdk_aac -b:a <bitrate> -afterburner 1 <output>
VBR mode:
aconv -i <input> -c:a libfdk_aac -flags +qscale -global_quality [1-5] -afterburner 1 <output>
- afterburner
- See afterburner.
- global_quality
- Values 1-5. See Bitrate mode.