Overview
CW-AAC
A native Windows AAC/M4A encoder with quality-based VBR, constrained VBR, conventional bitrate mode, metadata handling and packet statistics in a compact command-line tool.
Features
- Quality-based VBR from -q 0.1 to 10; higher q values mean higher quality
- cVBR mode with integer quality levels 1 to 5
- Conventional bitrate mode with -b
- AAC in an M4A container
- Global metadata copying with --copy-tags
- Individual title, artist, album, track and other metadata fields
- AAC packet statistics with --stats
- Windows x64 and x86 release builds
Practical comparison
How CW-AAC differs
CW-AAC provides three deliberately simple ways to target an encode: quality-based VBR, constrained VBR and a direct bitrate mode. That makes it useful both for quality-first music encoding and for workflows where bitrate behaviour needs to be more predictable.
Quality VBR
The normal -q mode targets encoding quality rather than a fixed bitrate. The encoder is free to spend more or less data according to the material, making this the natural choice when perceptual quality is the main priority.
cVBR: constrained VBR
With --cvbr, CW-AAC selects its constrained-VBR workflow using integer -q levels 1 through 5. It sits between unrestricted quality-based VBR and the direct bitrate mode.
Bitrate mode
Using -b selects a direct bitrate-oriented workflow and overrides -q. This is useful when output size, compatibility or a known bitrate target matters more than quality-driven bitrate allocation.
Command line
Command examples
Default quality VBR
Encode using the default quality setting of -q 2. In CW-AAC, higher q values mean higher quality.
C:\> cw-aac.exe input.flac output.m4aHigher quality VBR
Use quality level q4. CW-AAC runs upward: q0.1 is the lowest end of the scale and q10 is the highest.
C:\> cw-aac.exe input.flac output.m4a -q 4Constrained VBR
Enable cVBR and select integer quality level 3.
C:\> cw-aac.exe input.flac output.m4a --cvbr -q 3192 kbit/s bitrate mode
Select bitrate mode at 192 kbit/s. The bitrate setting overrides -q.
C:\> cw-aac.exe input.flac output.m4a -b 192kCopy source metadata
Copy global metadata from the input while encoding.
C:\> cw-aac.exe input.flac output.m4a -q 3 --copy-tagsSet metadata manually
Set common metadata fields directly from the command line.
C:\> cw-aac.exe input.wav output.m4a -q 3 --title "Track Title" --artist "Artist" --album "Album"Show packet statistics
Print AAC packet statistics after encoding.
C:\> cw-aac.exe input.flac output.m4a -q 3 --statsProject notes
CW-AAC quality numbering runs upward: higher q means higher quality. Normal VBR accepts q0.1 to q10; cVBR uses integer q1 to q5.
The website follows the terminology used by the final executable: CW-AAC 1.0.1 exposes normal quality VBR, --cvbr constrained VBR, and -b bitrate mode.
Detailed implementation behaviour remains intentionally undocumented; the public description focuses on how each mode is selected and what type of workflow it targets.
Downloads
Verification
Release downloads can be verified independently using the published SHA-256 checksum and Windows digital signature.