Difference between revisions of "Fraunhofer FDK AAC"
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== Afterburner == | == 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. | ''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 == | ||
| + | {|class="wikitable" | ||
| + | ! 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 == | == [lib]fdk-aac == | ||
| Line 50: | Line 73: | ||
;-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>: | + | ;-v <0-5>:[[#Bitrate modes|bitrate mode]] Only 0-5 used. 0=CBR @ value given in -r. Default is 0. |
=== ffmpeg === | === ffmpeg === | ||
Revision as of 19:24, 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.
Contents
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.
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.
avconv
libfdk-aac can be used with avconv, but requires a custom build of avconv.
