Audio to CD Format WAV Converter

Version 1.0

Overview

Audio to CD Format WAV Converter is a specialized tool for converting audio files in WAV, FLAC, and ALAC formats to CD-standard WAV files (44.1kHz/16bit). High-quality resampling and dithering processes minimize audio quality degradation.

Key Features

Multiple Format Support: Supports WAV, FLAC, and ALAC (M4A) files
CD Standard Conversion: Converts any sample rate/bit depth to 44.1kHz/16bit WAV
High-Quality Processing: Highest quality resampling using librosa Kaiser method
Smart Dithering: Applies TPDF triangular dithering only to files exceeding 16-bit depth
ID3v2.3 Tag Preservation: Preserves title, artist, album, composer, cover art, etc. in ID3v2.3 format (RIFF INFO chunks removed)
Parallel Processing: Efficiently processes multiple files simultaneously using half of CPU cores
Smart Skip: Processes CD-format WAV files to unify tag format

System Requirements

Windows 11 (64-bit)
Windows 10 (64-bit) also supported
FFmpeg required for ALAC (M4A) file processing (used internally by pydub)

How to Use

Basic Usage

Prepare audio files to convert (WAV/FLAC/ALAC)
Drag and drop files onto audio_to_cd_format_wav.exe
Processing starts automatically
After completion, an output_cd44 folder is created in the same location as the source files
Converted files are saved as original_filename_cd.wav

Processing Folders

Drag and drop a folder containing audio files onto audio_to_cd_format_wav.exe
All supported files directly in the folder will be batch processed

Tip: You can drag and drop multiple files or folders simultaneously.

Note: Files in subfolders are not processed. Only files directly in the dropped folder are targeted.

Supported Formats

Input Formats

Format	Extension	Supported Bit Depth	Notes
WAV	.wav	16bit, 24bit, 32bit (int/float)	PCM format
FLAC	.flac	16bit, 24bit, 32bit	Lossless compression
ALAC	.m4a	16bit, 24bit, 32bit	Apple Lossless (via FFmpeg)

Output Format

Format: WAV (PCM)
Sample Rate: 44.1kHz (44,100Hz)
Bit Depth: 16bit
Tag Format: ID3v2.3 only (no RIFF INFO chunks)

Processing Details

Conversion Specifications

Item	Specification
Output Sample Rate	44.1kHz (44,100Hz)
Output Bit Depth	16bit PCM
Resampling Method	librosa Kaiser (highest quality)
Dithering Method	TPDF triangular dithering (only for files exceeding 16-bit)
Parallel Processing	Half of CPU cores (e.g., 8 cores → 4 threads)
Tag Format	ID3v2.3 (title, artist, album, composer, cover art, etc.)

Processing Flow

File Reading: WAV/FLAC via soundfile, ALAC via pydub
Bit Depth Detection: Determines if file is 16-bit or less, or exceeds 16-bit
Resampling: High-quality resampling if sample rate is not 44.1kHz
Bit Depth Conversion: Applies dithering only for files exceeding 16-bit when converting to 16-bit
File Saving: Saves as clean WAV file without RIFF INFO chunks
ID3v2.3 Tag Copy: Writes tag information from source file in ID3v2.3 format

Dithering Application Rules

Applied to: Files with bit depth exceeding 16-bit (24bit, 32bit, etc.)
Not applied to: Files with 16-bit or less depth (avoids unnecessary processing and preserves quality)

Output Files

Output Location

Converted files are saved in an automatically created output_cd44 folder within the same directory as the source files.

File Naming

Output files are named "original_filename_cd.wav".
Example: mysong.flac → mysong_cd.wav

Note: Original files are not overwritten. Source files remain after conversion.

Handling Same-Named Files

If you process files with the same name but different extensions simultaneously (e.g., song.wav, song.flac, song.m4a), they will all output as song_cd.wav, resulting in the last processed file overwriting previous ones.

Understanding Processing Results

During processing, the following information is displayed in the command window:

[CONVERT]: File was converted (displays source sample rate/format)
[SKIP]: Already CD-format WAV, but tags were unified to ID3v2.3
[ERROR]: An error occurred

After completion, the following statistics are displayed:

CPU core count
Parallel thread count
Number of converted files
Number of skipped files (already CD format)
Number of files with errors
Output folder path

Frequently Asked Questions

Q1: What audio files are supported?

A: WAV (PCM format), FLAC, and ALAC (M4A) are supported. Sample rate and bit depth are not restricted. Examples: 48kHz/24bit, 96kHz/32bit, 192kHz/24bit, etc.

Q2: What happens to files already at 44.1kHz/16bit WAV?

A: Sample rate and bit depth conversion is skipped, but the following processing occurs:

RIFF INFO chunks are removed
Only ID3v2.3 tags are preserved
Saved to output_cd44 folder as original_filename_cd.wav

Processing result displays "SKIP (already CD format)".

Q3: Will audio quality degrade?

A: High-quality resampling algorithms (librosa Kaiser) and dithering processes minimize quality degradation. However, when sample rate or bit depth decreases from the source, theoretical information content is reduced.

Q4: Are stereo/mono files supported?

A: Yes, both are supported. Multi-channel files (5.1ch, etc.) can also be processed.

Q5: How long does processing take?

A: Time varies depending on file size and source sample rate. As a guideline, a 5-minute song (96kHz/24bit) completes in several tens of seconds. Parallel processing enables efficient simultaneous processing of multiple files.

Q6: Are metadata (tag information) preserved?

A: Yes, the following tag information is preserved in ID3v2.3 format:

Title (song name)
Artist
Album
Album Artist
Composer
Genre
Year (release date)
Track number
Cover art (album artwork)

Important: RIFF INFO chunks are removed, and only ID3v2.3 tags are preserved. This unifies the tag format and improves compatibility.

Q7: Are FLAC and ALAC tags also converted?

A: Yes, standard tag information from FLAC (Vorbis Comment) and ALAC (MP4 tags) is automatically converted and preserved in ID3v2.3 format.

Q8: ALAC files cannot be processed

A: ALAC file processing requires FFmpeg. Pydub uses FFmpeg internally for processing. Errors occur if FFmpeg is not installed or not in the system PATH.

Q9: About 32bit FLAC file processing

A: Some 32bit FLAC files cannot be read by soundfile, so librosa automatically falls back for processing. Warning messages are suppressed internally and not displayed to users, and processing completes normally.

Q10: What if an error occurs?

A: An error message is displayed. Main causes include:

Corrupted file
Unsupported format
Insufficient disk space
FFmpeg not installed (when processing ALAC files)

Precautions

This tool is exclusively for WAV, FLAC, and ALAC formats. Lossy compression formats like MP3 and AAC are not supported
Files in subfolders are not processed. When dropping a folder, only files directly in it are targeted
Processing files with the same name but different extensions simultaneously (e.g., song.flac and song.m4a) will result in output file overwriting
Errors may occur if file or folder names contain invalid characters (\/:*?"<>|)
Do not close the window during processing
Ensure sufficient free disk space when processing large numbers of files
Original files are not deleted, but we recommend backing them up just in case

Troubleshooting

Program won't start

Verify you're running Windows 11/10 (64-bit)
Check if the exe file is corrupted
Check if it's blocked by antivirus software

Cannot process ALAC files

Verify FFmpeg is installed
Check if FFmpeg is in your system PATH
Verify pydub is correctly installed

Cannot find converted files

Check if an output_cd44 folder was created in the same directory as source files
Verify the output path in the processing result message

Audio doesn't play correctly

Verify the source file plays correctly
Check if the converted file is properly in CD format (44.1kHz/16bit) using a media player

Tag information not displayed

Verify your media player supports ID3v2.3 tags
Check if the source file contained tag information

Technical Information

Libraries Used

soundfile: WAV/FLAC file reading and writing
pydub: ALAC file reading (via FFmpeg)
librosa: High-quality resampling (including fallback for 32bit FLAC)
numpy: Audio data numerical processing
mutagen: ID3v2.3 tag reading and writing

About Dithering

This tool uses TPDF (Triangular Probability Density Function) triangular dithering only when reducing bit depth from above 16-bit to 16-bit. This converts quantization noise into perceptually less noticeable noise, minimizing quality degradation. Files originally at 16-bit or below avoid unnecessary processing, preserving quality.

About ID3v2.3 Tags

Output WAV files contain only ID3v2.3 format tags. RIFF INFO chunks are intentionally removed. This unifies the tag format and improves compatibility with various media players.

About Parallel Processing

This tool automatically detects your PC's CPU core count and performs parallel processing with half that number of threads. For example, an 8-core CPU uses 4 threads. This efficiently processes multiple files simultaneously without overloading the system.

License and Disclaimer

This software is free to use for both personal and commercial purposes.

The author assumes no responsibility for any damages arising from the use of this software. Use at your own risk.

Version History

Version 1.0 (2025-12-04) - Initial Release
- Support for WAV, FLAC, and ALAC formats
- ID3v2.3 tag only preservation (RIFF INFO removal)
- Dithering applied only to files exceeding 16-bit
- Parallel processing with half of CPU cores
- High-quality resampling (librosa Kaiser)