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Dynamic range compression (DRC) in AAC



Dear group,
          I am not sure if this is a right place to post this question. I hope some group members would be interested in the topic.

This is regarding the excl_chn_mask[] bits in the dynamic-range_info() of the AAC bit stream. Assume the excl_chn_mask[] bit is set for a channel in the AAC bit stream.

Does that mean? 

1. we are not interested to change the DRC values (no. of bands, gain etc) for this channel using the recently transmitted DRC parameters but the DRC processing (spectral line multiplication) must go on this channel with the previously transmitted values.

or

2. we would like to stop DRC processing for this channel from now on till we get the DRC parameters for this channel in a later frame.

or

We would like to stop DRC processing (spectral line multiplication) on this frame for this channel but continue DRC processing from  next frame using the previous value.

Which one is correct ?

Thanks and regards,
Pinaki