Section
https://w3c.github.io/epub-specs/epub34/authoring/#sec-core-media-types
Describe the problem
The core media types currently includes MP3 audio. MP3 audio is widely available and supported. However, variable bitrate MP3s are not well suited for precise seeking, and many audio players (including the Android ExoPlayer) cannot accurately seek to precise timestamps within a VBR MP3.
This is especially troublesome for Media Overlays, where the SMIL consists of a series of clipBegin/clipEnd pairs that the reading system must seek to on-demand. This can create a completely broken readaloud experience for readers, especially in long audio files, where entirely the wrong clip of audio is played for the current text range.
Describe the fix or new feature you propose
Add a warning to the core media types section about the potential pitfalls of VBR MP3 audio.
Section
https://w3c.github.io/epub-specs/epub34/authoring/#sec-core-media-types
Describe the problem
The core media types currently includes MP3 audio. MP3 audio is widely available and supported. However, variable bitrate MP3s are not well suited for precise seeking, and many audio players (including the Android ExoPlayer) cannot accurately seek to precise timestamps within a VBR MP3.
This is especially troublesome for Media Overlays, where the SMIL consists of a series of clipBegin/clipEnd pairs that the reading system must seek to on-demand. This can create a completely broken readaloud experience for readers, especially in long audio files, where entirely the wrong clip of audio is played for the current text range.
Describe the fix or new feature you propose
Add a warning to the core media types section about the potential pitfalls of VBR MP3 audio.