Encoders must be able to encode an audio-only stream to meet the requirements Apple mandates for video content delivered in iOS applications.
To provide a seamless audio experience, use encoders capable of encoding the audio track of all renditions to 64 kbps. This avoids audible clips or other distortions when the device switches from one rendition to another.
To provide higher quality audio, use encoders that can encode audio tracks at higher bitrates than the 64 kbps required for the lowest rendition. By encoding at higher bitrates, the user should experience higher fidelity audio but may experience audible clips or other distortions when the device switches from one rendition to another. Before initiating a live event, ensure that any quality issues experienced when switching between the required 64 kbps audio-only stream and higher quality streams are acceptable.