Changes between Version 50 and Version 51 of Encode/AAC


Ignore:
Timestamp:
Oct 4, 2016, 7:27:21 PM (12 months ago)
Author:
llogan
Comment:

moved libfaac into deprecated/removed section

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  • Encode/AAC

    v50 v51  
    33[[http://en.wikipedia.org/wiki/Advanced_Audio_Coding|Advanced Audio Coding (AAC)]] is the successor format to MP3, and is defined in MPEG-4 part 3 (ISO/IEC 14496-3). It is often used within an MP4 container format; for music the .m4a extension is customarily used. The second-most common use is within MKV (Matroska) files because it has better support for embedded text-based soft subtitles than MP4. The examples in this guide will use the extensions MP4 and M4A. 
    44 
    5 FFmpeg can support three AAC-LC encoders (`aac`, `libfaac`, `libfdk_aac`) and one HE-AAC(v1/2) encoder (`libfdk_aac`). The licenses of `libfaac` and `libfdk_aac` are not compatible with the GPL, so the GPL does not permit distribution of binaries containing code licensed under these licenses when GPL-licensed code is also included. Therefore these encoders have been designated as "non-free", and you cannot download a pre-built ffmpeg that supports them. This can be resolved by [[CompilationGuide|compiling ffmpeg]] yourself. 
     5FFmpeg can support two AAC-LC encoders (`aac` & `libfdk_aac`) and one HE-AAC(v1/2) encoder (`libfdk_aac`). The license of `libfdk_aac` is not compatible with the GPL, so the GPL does not permit distribution of binaries containing incompatible code when GPL-licensed code is also included. Therefore this encoder have been designated as "non-free", and you cannot download a pre-built ffmpeg that supports it. This can be resolved by [[CompilationGuide|compiling ffmpeg]] yourself. 
    66 
    77See also [[Encode/HighQualityAudio]] for general guidelines on FFmpeg audio encoding (which also includes a comparison of which AAC encoder is best quality). 
     
    1111= libfdk_aac =#fdk_aac 
    1212 
    13 The Fraunhofer FDK AAC codec library. This is currently the highest-quality AAC encoder available with ffmpeg. Requires ffmpeg to be configured with `--enable-libfdk-aac` (and additionally `--enable-nonfree` if you're also using `--enable-gpl`). But beware, it defaults to a low-pass filter of around 14kHz ([[http://wiki.hydrogenaud.io/index.php?title=Fraunhofer_FDK_AAC#Bandwidth|details]]). If you want to preserve higher frequencies, use `-cutoff 18000`.  Adjust the number to the upper frequency limit you prefer, keeping in mind that a higher limit may audibly reduce the overall quality. 
     13The Fraunhofer FDK AAC codec library. This is currently the highest-quality AAC encoder available with ffmpeg. Requires ffmpeg to be configured with `--enable-libfdk-aac` (and additionally `--enable-nonfree` if you're also using `--enable-gpl`). But beware, it defaults to a low-pass filter of around 14kHz ([[http://wiki.hydrogenaud.io/index.php?title=Fraunhofer_FDK_AAC#Bandwidth|details]]). If you want to preserve higher frequencies, use `-cutoff 18000`.  Adjust the number to the upper frequency limit only if you need to; keeping in mind that a higher limit may audibly reduce the overall quality. 
    1414 
    1515Detailed information about the FDK AAC library (not FFmpeg specific) can be found at [http://wiki.hydrogenaud.io/index.php?title=Fraunhofer_FDK_AAC HydrogenAudio Knowledgebase: Fraunhofer FDK AAC]. 
     
    133133---- 
    134134 
     135= Deprecated/removed encoders = 
     136 
    135137= libfaac = 
    136138 
    137 Freeware Advanced Audio Coder. Requires ffmpeg configuration with `--enable-libfaac --enable-nonfree`. Note that you will not get as good results as with `libfdk_aac`. 
    138  
    139 == Variable Bit Rate (VBR) Example == 
    140 {{{ 
    141 ffmpeg -i input.wav -c:a libfaac -q:a 100 output.m4a 
    142 }}} 
    143  
    144 Range for `-q:a` is 10-500 and is similar to using the `-q` option in standalone `faac`. 100 is a good value to try. 
    145  
    146 == Average Bit Rate (ABR) Example == 
    147 {{{ 
    148 ffmpeg -i input.wav -c:a libfaac -b:a 192k output.m4a 
    149 }}} 
    150  
    151 `libfaac` does not support a true Constant Bit Rate (CBR) mode. 
    152  
    153 ---- 
    154  
    155 = Deprecated/removed encoders = 
     139Freeware Advanced Audio Coder. [http://git.videolan.org/?p=ffmpeg.git;a=commit;h=dc0f711459e0c682bf9f94ba38d26736e90cff45 Support for this library has been removed]. 
    156140 
    157141== libvo_aacenc == 
    158142 
    159143!VisualOn AAC encoding library. [http://git.videolan.org/?p=ffmpeg.git;a=commit;h=e07e88cd82f78644ddcb10d7d3e0dd624fffe274 Support for this library has been removed]. Use the native FFmpeg encoder instead: it provides better quality and supports more than 2 channels. 
    160  
    161 ---- 
    162144 
    163145== libaacplus == 
     
    199181== Which encoder provides the best quality? == 
    200182 
    201 For AAC-LC the likely answer is: `libfdk_aac` > Native FFmpeg AAC encoder (`aac`) > `libfaac`. 
     183For AAC-LC: `libfdk_aac` > Native FFmpeg AAC encoder (`aac`). 
    202184 
    203185For HE-AAC you have one choice: `libfdk_aac`.