A key describing the target reference level that was assumed at the encoder for calculation of attenuation gains for clipping prevention. This information can be provided if it is known, otherwise a worst-case assumption is used.
The value is given as an integer value between 0 and 127, and is calculated as -0.25 * Target Reference Level in dBFS. Therefore, it represents the range of Full Scale (0 dBFS) to -31.75 dBFS. The default value is the worst-case assumption of 127.
The value is ignored when heavy compression is used (see MediaFormat.KeyAacDrcHeavyCompression).
This key is only used during decoding.