Audio File Normalisation for Digital Asset Management

This repository addresses a common challenge encountered within Digital Asset Management (DAM) systems: the ingestion of diverse audio file formats. This document outlines a robust methodology for normalising such assets into a unified and highly compatible .mp4 container, ensuring seamless integration, consistent playback, and long-term preservation within a DAM environment.

The Challenge: Diverse Audio Assets

A recent operational scenario involved a considerable collection of media files, encompassing a variety of audio formats such as .mp3, .opus, and .m4a. The objective was to integrate these valuable assets into our DAM system. However, the inherent preference of DAM systems for consistency and a standardised format presented a significant hurdle. Disparate formats often necessitate specific codecs, complicate metadata handling, and pose risks of obsolescence, thereby impeding efficient search, categorisation, and universal playback.

The Solution: Standardisation to MP4

To mitigate these operational difficulties, a pre-ingestion normalisation strategy has been devised. This approach centres on converting all audio assets to a uniform .mp4 container. It is important to note that while this provides a unified and broadly compatible format, it will not be a like-for-like replication of the original audio-only files. Instead, the .mp4 container, incorporating a minimal visual track, serves as a pragmatic common denominator for simplicity and extensive compatibility within the DAM.

Technical Implementation: Leveraging FFmpeg

By utilising FFmpeg and its companion tool, FFprobe (for media analysis), we can programmatically convert the audio collection into the desired .mp4 format. The .mp4 container, coupled with the H.264 video codec and AAC audio codec, represents a widely accepted standard suitable for web playback and integration with contemporary DAM systems.

Batch Processing Script

The following Bash script facilitates this batch operation, automating the conversion process:

mkdir converted_videos # Ensure this directory exists before running the loop

for f in *.mp3 *.opus *.m4a; do
  if [ -f "$f" ]; then
    filename=$(basename "$f" | sed 's/\.[^.]*$//')
    
    # Get audio duration in seconds
    duration=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$f")
    
    # Use the duration in the ffmpeg command
    ffmpeg -i "$f" -f lavfi -i "color=c=black:s=1920x1080:r=1" \
           -c:v libx264 -pix_fmt yuv420p -tune stillimage \
           -c:a aac -b:a 320k \
           -t "$duration" \
           "converted_videos/${filename}.mp4"
  fi
done