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TagQt provides FLAC re-encoding capabilities to convert FLAC files to a standardized format (24-bit/48kHz) while preserving all metadata and cover art.

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Overview

The FLAC re-encoding feature uses FFmpeg to convert FLAC files to 24-bit/48kHz format with compression level 5, ensuring consistent audio quality across your library.

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Requirements

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FFmpeg Installation

The re-encoding feature requires FFmpeg to be installed on your system: 
sudo apt install ffmpeg
TagQt automatically detects if FFmpeg is installed. If not available, you’ll see an error message with installation instructions.

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Encoding Specifications

The re-encoding process converts FLAC files to the following specifications:
ParameterValueDescription
Sample Format32-bit signed integer (s32)Provides 24-bit depth
Sample Rate48000 HzProfessional audio standard
Compression Level5Balance between size and speed
MetadataPreservedAll tags retained
Cover ArtPreservedAlbum artwork maintained

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FFmpeg Command

The actual FFmpeg command used (from flac.py:62-71): 
cmd = ['ffmpeg', '-y', '-i', filepath, 
       '-map_metadata', '0',
       '-c:a', 'flac', 
       '-compression_level', '5',
       '-sample_fmt', 's32',
       '-ar', '48000',
       '-c:v', 'copy', temp_path]

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Command Breakdown

  • -y - Overwrite output file without asking
  • -i filepath - Input file
  • -map_metadata 0 - Copy all metadata from input
  • -c:a flac - Use FLAC codec for audio
  • -compression_level 5 - Medium compression
  • -sample_fmt s32 - 32-bit signed integer samples (24-bit depth)
  • -ar 48000 - 48kHz sample rate
  • -c:v copy - Copy video streams (cover art) as-is

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Metadata Preservation

The re-encoding process carefully preserves all metadata:

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Tags Preserved

All standard and extended tags are preserved during re-encoding: 
# From flac.py:42-47
for attr in ['title', 'artist', 'album', 'year', 'genre', 
             'track_number', 'disc_number', 'album_artist', 
             'comment', 'lyrics', 'bpm', 'initial_key', 
             'isrc', 'publisher']:
    val = getattr(original_meta, attr)
    if val:
        tags_to_preserve[attr] = val

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Cover Art Preservation

Cover art is extracted before encoding and restored afterward: 
# From flac.py:49
cover_data = original_meta.get_cover()

# After encoding (flac.py:87-88)
if cover_data:
    new_meta.set_cover(cover_data)

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Using FLAC Re-encoding

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From the Menu

  1. Navigate to Tools → File Actions → Re-encode FLAC
  2. Choose Selected or All Visible
  3. Wait for the encoding process to complete
  4. Review the results in the batch status dialog

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From the Context Menu

  1. Right-click on selected FLAC files
  2. Choose Re-encode FLAC (Selected)

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From the Sidebar

When viewing a FLAC file:
  1. Click the Re-encode FLAC button in the sidebar
  2. The current file will be re-encoded

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From the Command Palette

  1. Press Ctrl+K
  2. Search for “Re-encode FLAC”
  3. Select the command

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File Processing

The re-encoding process follows these steps:
  1. Validation - Confirms file is a FLAC file
  2. Metadata Backup - Extracts all tags and cover art
  3. Temporary Encoding - Creates encoded file in temp location
  4. Metadata Restoration - Restores all tags to new file
  5. File Replacement - Replaces original with re-encoded file
  6. Cleanup - Removes temporary files
# From flac.py:57-95
temp_fd, temp_path = tempfile.mkstemp(suffix='.flac')
# ... encoding process ...
shutil.move(temp_path, filepath)  # Replace original

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Error Handling

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Common Errors

Error: “Neither flac nor ffmpeg is installed”Solution: Install FFmpeg using your system’s package manager (see Requirements section)
Error: “Not a FLAC file”Solution: The re-encoding feature only works with .flac files. Other formats are automatically skipped.
Error: “Encoding failed: [stderr output]”Solution: Check the error message for details. Common causes include:
  • Corrupted input file
  • Insufficient disk space
  • File permissions issues

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Batch Operations

When re-encoding multiple files:
  • Progress is displayed in real-time
  • Each file is processed sequentially
  • Failed files don’t stop the batch operation
  • Detailed results are available in the batch status dialog
  • Click the progress bar to view detailed status
Re-encoding is a CPU-intensive operation. For large libraries, consider running the operation in smaller batches or when you don’t need to use your computer for other tasks.

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Performance Considerations

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Processing Time

Re-encoding time depends on:
  • Original file size and length
  • CPU performance
  • Compression level (fixed at 5)
Typical processing time: 1-3 seconds per minute of audio

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Disk Space

Temporary disk space required:
  • At least 2x the size of the largest file being processed
  • Temporary files are automatically cleaned up after processing

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Best Practices

Re-encoding is a destructive operation. The original file is replaced with the re-encoded version. Always maintain backups of your original files.

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Recommendations

  1. Test first: Re-encode a single file and verify the output before batch processing
  2. Check metadata: Verify that all tags and cover art are preserved after encoding
  3. Listen test: Compare audio quality before and after encoding
  4. Backup: Always maintain backups of your original FLAC files
  5. Free space: Ensure adequate disk space before starting large batch operations

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Technical Details

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Source Code Reference

  • Source: tagqt/core/flac.py
  • Class: FlacEncoder
  • Main Method: reencode_flac(filepath)
  • Worker: FlacReencodeWorker (in tagqt/ui/workers.py)

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Encoder Detection

# From flac.py:17-23
@staticmethod
def get_available_encoder():
    if FlacEncoder.is_flac_available():
        return 'flac'
    elif FlacEncoder.is_ffmpeg_available():
        return 'ffmpeg'
    return None
TagQt first checks for the flac command-line tool, then falls back to FFmpeg. Both can be used for re-encoding.

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