Frequently Asked Questions: Technical

StoryMusic.io provides only high-quality, uncompressed PCM audio files in AIFF format using 24-bit depth and 48 kHz sample rate, which is the digital standard for professional AV applications. During the mixing and mastering stages, particular attention is given to the preservation of dynamics, to the absence of clipping or undesirable distortion. And that until the output of the audio file in its delivery format.

Technically, there is no difference between the quality of AIFF and WAV audio files. Both support high-resolution audio and are in uncompressed format. On the other hand, in a professional context, AIFF supports embedded metadata, unlike WAV. AIFF is, therefore, more convenient for sorting and archiving purposes. AIFF, like WAV, is cross-platform and can be played natively on most devices.

These specifications based on the ITU-R BS 1770 accurately match the EBU R128 and fit perfectly within the tolerance range of ATSC A/85 or ARIB TR-B32. The chosen highest loudness value allows further normalization adjustments without affecting the audio quality (e.g., if you need to set precisely the loudness target at -24 or -27 LKFS).

• Integrated loudness: -23 LUFS (*)
• Average dynamic: ± 16 LU
• Short-term max.: ≤ -18 LUFS
• Momentary max.: ≤ -15 LUFS
• True peak max.: ≥ -12 dBTP and ≤ -6 dBTP

(*) One unit of LUFS is equal to 1 LKFS.

The integrated loudness target at -14 dB LKFS accurately matches the most recent YouTube volume normalization value and those from other popular streaming platforms. Therefore, any automatic normalization process will not impact the audio quality and prevent distortion or clipping. If necessary, you can also normalize your tracks for other lower values (e.g., if you need to set the target volume to -16 or -18 LKFS for a podcast).

• Integrated loudness = -14 LUFS
• Average dynamic = ±12.7 LU
• Short-term max.: N/A
• Momentary max.: ≤ -8 LUFS
• True peak max = ± 1.3 dBTP

You will find some additional information with the audio tracks.

• For example, a spectrogram, which somehow represents the music fingerprint, is created during the audio conversion. Helpful for getting an overview of the track, such as the distribution of dynamic or quiet movements or parts with dominant high or low frequencies.
• Similarly, you can find an accurate report with raw audio values, such as RMS levels, peaks, etc.

These pieces of information should satisfy quality control managers.

For your convenience, all the audio files follow a naming convention, applicable when you work in a professional AV environment.

Here is the scheme: STM_Title_48k_24b_2ch_K14.aiff

• STM is the abbreviation of StoryMusic.io, the publishing platform.
• Title, as the track title.
• 48k is the abbreviation of 48 kHz sample rate.
• 24b is the abbreviation of 24-bits depth.
• 2ch corresponds to the two channels of a stereo audio file.
• K14 (or ITU) corresponds to the loudness level of the mastered audio file.
• AIFF (and m4a) is the final file format of the audio track.

At a bit rate similar to MP3, M4A encoding (based on Advanced Audio Coding, AAC) provides superior sound quality. That's why I decided to use this audio format for the preview and free tracks delivered on this site. The audio quality is the same as what you find on iTunes. M4A format is also natively supported on Apple devices, any modern web browser, and popular video editing software but may require an app to play on specific mobile devices.

You will find more exhaustive information about the m4a format on the Wikipedia page dealing with this subject.

No. If you need a lightweight file for some reason, you can use the m4a file that came with your order. Note that the streaming platform will likely re-encode the file. The process will then lead to a loss of quality. Whenever possible, always use the uncompressed PCM AIFF files for your project. In this regard, here are the recommended encoding specifications for YouTube: Encoding specifications for music videos.