Nero AAC
A commercial implementation of both LC AAC and HE AAC, Nero AAC is produced by Nero AG as part of their Nero Digital line of products. It is generally percieved to have the highest quality VBR LC AAC implementation (although QuickTime AAC beats it in CBR mode at 128kbps). The codec can also create HEv1/v2 AAC streams for extremely low bitrates and supports multi-channel surround sound encoding. As of May 2006, Nero AAC is available for free as a command line tool called "Nero Digital Audio".
Command Line Options
Usage
neroAacEnc.exe [options] -if <input-file> -of <output-file>
<input-file>: Path to source file to encode. The file must be in Microsoft WAV format and contain PCM data. Specify - to encode from stdin.
<output-file>: Path to output file to encode to, in MP4 format.
Quality/Bitrate Control
-q <number>: Enables "target quality" mode. <number> is floating-point number between 0 and 1.
-br <number>: Specifies "target bitrate" mode. <number> is target bitrate in bits per second.
-cbr <number>: Specifies "target bitrate (streaming)" mode. <number> is target bitrate in bits per second.
When none of above quality/bitrate options is used, the encoder defaults to equivalent of -q 0.5
Multipass Encoding
-2pass: Enables two-pass encoding mode. Note that two-pass more requires a physical file as input, rather than stdin.
-2passperiod <number>: Overrides two-pass encoding bitrate averaging period, in milliseconds. Specify zero to use least restrictive value possible (default).
Advanced Features / Troubleshooting
-lc: Forces use of LC AAC profile (HE features disabled)
-he: Forces use of HE AAC profile (HEv2 features disabled)
-hev2: Forces use of HEv2 AAC profile
Note that the above switches (-lc, -he, -hev2) should not be used; optimal AAC profile is automatically determined from quality/bitrate settings when no override is specified.
-hinttrack: Generates an RTP hint track in output MP4 file.
-ignorelength: Ignores length signaled by WAV headers of input file. Useful for certain frontends using stdin.
Example EAC Settings
The following settings are examples of what one might use for music and spoken word sources, respectively. Files will be tagged properly using these commands via neroaactag.exe. These commands do run ReplayGain on the files.
This is the syntax for older versions of EAC. For 1.0 beta 2 and above, variables have a changed syntax. See [[1]]
320kbps CBR AAC (Forced LC)
Program, including path, used for compression: C:\Windows\system32\cmd.exe
Additional Command Line Options: /c ""C:\path\to\neroaacenc.exe" -cbr 320000 -lc -if %s -of %d && "C:\path\to\Neroaactag.exe" %d -meta:artist="%a" -meta:album="%g" -meta:track="%n" -meta:title="%t" -meta:genre="%m" -meta:year="%y""
Q0.3 VBR AAC (Forced HE)
Program, including path, used for compression: C:\Windows\system32\cmd.exe
Additional Command Line Options: /c ""C:\Program Files\Exact Audio Copy\neroaacenc.exe" -q 0.3 -he -if %s -of %d && "C:\Program Files\Exact Audio Copy\Neroaactag.exe" %d -meta:artist="%a" -meta:album="%g" -meta:track="%n" -meta:title="%t" -meta:genre="%m" -meta:year="%y""
Nero AAC in Foobar
The Nero AAC Codec can be used inside Foobar2000's convert function.
References
Discussion Thread for the Recommended Setting Sticky