Decode dynamic range control improvements

* AAC-Decoder

   - Only set the program reference level if it has changed compared to the
     previous value. This allows setting it on a frame-by-frame basis without
     limitations.
     Modified file(s):
        libAACdec/src/aacdec_drc.cpp
        libAACdec/src/aacdec_drc.h

   - Add expiry counter for the program reference level.
     Modified file(s):
        libAACdec/src/aacdec_drc.cpp
        libAACdec/src/aacdec_drc_types.h

   - Disable scaling of light compression gain values when heavy compression
     mode is enabled to have the full light compression as fallback if no heavy
     values are available.
     Modified file(s):
        libAACdec/src/aacdec_drc.cpp
        libAACdec/src/aacdecoder_lib.cpp
        libAACdec/src/aacdec_drc_types.h

   - Change initialization and channel disabling to improve start-up behavior in
     SBR decoder.
     Modified file(s):
        libSBRdec/src/sbrdecoder.cpp
        libSBRdec/src/sbrdec_drc.cpp

Bug 9428126

Change-Id: Ie1d3949c53910506da2547d32fe3bf6ee7606eb4

1 files changed, 6 insertions, 2 deletions

diff --git a/libAACdec/src/aacdec_drc_types.h b/libAACdec/src/aacdec_drc_types.h
index e7c6f1a..1b5cd76 100644
--- a/libAACdec/src/aacdec_drc_types.h
+++ b/libAACdec/src/aacdec_drc_types.h
@@ -132,8 +132,10 @@ typedef struct
 
 typedef struct
 {
-  FIXP_DBL  cut;
-  FIXP_DBL  boost;
+  FIXP_DBL  cut;       /* The attenuation scale factor currently used.     */
+  FIXP_DBL  usrCut;    /* The latest attenuation scale factor set by user. */
+  FIXP_DBL  boost;     /* The boost scale factor currently used.           */
+  FIXP_DBL  usrBoost;  /* The latest boost scale factor set by user.       */
 
   UINT   expiryFrame;
   SCHAR  targetRefLevel;
@@ -154,6 +156,8 @@ typedef struct
   USHORT numThreads;                         /* The number of DRC data threads extracted from the found payload elements */
   SCHAR  progRefLevel;                       /* Program reference level for all channels */
 
+  UINT   prlExpiryCount;                     /* Counter that can be used to monitor the life time of the program reference level. */
+
   UCHAR  dvbAncDataAvailable;                  /* Flag that indicates whether DVB ancillary data is present or not */
   UINT   dvbAncDataPosition;                   /* Used to store the DVB ancillary data payload position in the bitstream (only one per frame) */
   UINT   drcPayloadPosition[MAX_DRC_THREADS];  /* Used to store the DRC payload positions in the bitstream */