Encoder ELD auto configurator
* AAC-Encoder
- Introduce ELD auto configurator to get predefined configuration at given
bitrate and sampling rate. The configurator selects SBR on/off and if SBR
enabled distinguishes between dualrate and downsampled SBR. In default
configuration the ELD auto configurator is enabled.
Modified file(s):
libAACenc\include\aacenc_lib.h
libAACenc\src\aacenc_lib.cpp
Bug 9428126
Change-Id: I01acc9c37e57c4154b3a818d496d538b7f8b227d
diff --git a/libAACenc/include/aacenc_lib.h b/libAACenc/include/aacenc_lib.h
index fcdaca5..f693bf5 100644
--- a/libAACenc/include/aacenc_lib.h
+++ b/libAACenc/include/aacenc_lib.h
@@ -342,6 +342,33 @@
we recommended to activate this feature.
\code aacEncoder_SetParam(hAacEncoder, AACENC_AFTERBURNER, 1); \endcode
+\subsection encELD ELD Auto Configuration Mode
+For ELD configuration a so called auto configurator is available which configures SBR and the SBR ratio by itself.
+The configurator is used when the encoder parameter ::AACENC_SBR_MODE and ::AACENC_SBR_RATIO are not set explicitely.
+
+Based on sampling rate and chosen bitrate per channel a reasonable SBR configuration will be used.
+\verbatim
+------------------------------------------------------------
+ Sampling Rate | Channel Bitrate | SBR | SBR Ratio
+-----------------+-----------------+------+-----------------
+ ]min, 16] kHz | min - 27999 | on | downsampled SBR
+ | 28000 - max | off | ---
+-----------------+-----------------+------+-----------------
+ ]16 - 24] kHz | min - 39999 | on | downsampled SBR
+ | 40000 - max | off | ---
+-----------------+-----------------+------+-----------------
+ ]24 - 32] kHz | min - 27999 | on | dualrate SBR
+ | 28000 - 55999 | on | downsampled SBR
+ | 56000 - max | off | ---
+-----------------+-----------------+------+-----------------
+ ]32 - 44.1] kHz | min - 63999 | on | dualrate SBR
+ | 64000 - max | off | ---
+-----------------+-----------------+------+-----------------
+ ]44.1 - 48] kHz | min - 63999 | on | dualrate SBR
+ | 64000 - max | off | ---
+------------------------------------------------------------
+\endverbatim
+
\section audiochCfg Audio Channel Configuration
The MPEG standard refers often to the so-called Channel Configuration. This Channel Configuration is used for a fixed Channel
@@ -881,8 +908,9 @@
AACENC_SAMPLERATE = 0x0103, /*!< Audio input data sampling rate. Encoder supports following sampling rates:
8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000, 64000, 88200, 96000 */
- AACENC_SBR_MODE = 0x0104, /*!< Configure SBR independently of the chosen Audio Object Type ::AUDIO_OBJECT_TYPE:.
- This parameter is only available for ELD.
+ AACENC_SBR_MODE = 0x0104, /*!< Configure SBR independently of the chosen Audio Object Type ::AUDIO_OBJECT_TYPE.
+ This parameter is for ELD audio object type only.
+ - -1: Use ELD SBR auto configurator (default).
- 0: Disable Spectral Band Replication.
- 1: Enable Spectral Band Replication. */
diff --git a/libAACenc/src/aacenc_lib.cpp b/libAACenc/src/aacenc_lib.cpp
index 8d32f3d..056958b 100644
--- a/libAACenc/src/aacenc_lib.cpp
+++ b/libAACenc/src/aacenc_lib.cpp
@@ -98,7 +98,7 @@
/* Encoder library info */
#define AACENCODER_LIB_VL0 3
#define AACENCODER_LIB_VL1 4
-#define AACENCODER_LIB_VL2 10
+#define AACENCODER_LIB_VL2 11
#define AACENCODER_LIB_TITLE "AAC Encoder"
#define AACENCODER_LIB_BUILD_DATE __DATE__
#define AACENCODER_LIB_BUILD_TIME __TIME__
@@ -235,7 +235,87 @@
} ;
-////////////////////////////////////////////////////////////////////////////////////
+typedef struct
+{
+ ULONG samplingRate; /*!< Encoder output sampling rate. */
+ ULONG bitrateRange; /*!< Lower bitrate range for config entry. */
+
+ UCHAR lowDelaySbr; /*!< 0: ELD sbr off,
+ 1: ELD sbr on */
+
+ UCHAR downsampledSbr; /*!< 0: ELD with dualrate sbr,
+ 1: ELD with downsampled sbr */
+
+} ELD_SBR_CONFIGURATOR;
+
+/**
+ * \brief This table defines ELD/SBR default configurations.
+ */
+static const ELD_SBR_CONFIGURATOR eldSbrAutoConfigTab[] =
+{
+ { 48000, 0, 1, 0 },
+ { 48000, 64001, 0, 0 },
+
+ { 44100, 0, 1, 0 },
+ { 44100, 64001, 0, 0 },
+
+ { 32000, 0, 1, 0 },
+ { 32000, 28000, 1, 1 },
+ { 32000, 56000, 0, 0 },
+
+ { 24000, 0, 1, 1 },
+ { 24000, 40000, 0, 0 },
+
+ { 16000, 0, 1, 1 },
+ { 16000, 28000, 0, 0 }
+
+};
+
+/*
+ * \brief Configure SBR for ELD configuration.
+ *
+ * This function finds default SBR configuration for ELD based on sampling rate and channel bitrate.
+ * Outputparameters are SBR on/off, and SBR ratio.
+ *
+ * \param samplingRate Audio signal sampling rate.
+ * \param channelMode Channel configuration to be used.
+ * \param totalBitrate Overall bitrate.
+ * \param eldSbr Pointer to eldSbr parameter, filled on return.
+ * \param eldSbrRatio Pointer to eldSbrRatio parameter, filled on return.
+ *
+ * \return - AACENC_OK, all fine.
+ * - AACENC_INVALID_CONFIG, on failure.
+ */
+static AACENC_ERROR eldSbrConfigurator(
+ const ULONG samplingRate,
+ const CHANNEL_MODE channelMode,
+ const ULONG totalBitrate,
+ UINT * const eldSbr,
+ UINT * const eldSbrRatio
+ )
+{
+ AACENC_ERROR err = AACENC_OK;
+ int i, cfgIdx = -1;
+ const ULONG channelBitrate = totalBitrate / FDKaacEnc_GetChannelModeConfiguration(channelMode)->nChannelsEff;
+
+ for (i=0; i<(sizeof(eldSbrAutoConfigTab)/sizeof(ELD_SBR_CONFIGURATOR)); i++) {
+ if ( (samplingRate <= eldSbrAutoConfigTab[i].samplingRate)
+ && (channelBitrate >= eldSbrAutoConfigTab[i].bitrateRange) )
+ {
+ cfgIdx = i;
+ }
+ }
+
+ if (cfgIdx != -1) {
+ *eldSbr = (eldSbrAutoConfigTab[cfgIdx].lowDelaySbr==0) ? 0 : 1;
+ *eldSbrRatio = (eldSbrAutoConfigTab[cfgIdx].downsampledSbr==0) ? 2 : 1;
+ }
+ else {
+ err = AACENC_INVALID_CONFIG; /* no default configuration for eld-sbr available. */
+ }
+
+ return err;
+}
static inline INT isSbrActive(const HANDLE_AACENC_CONFIG hAacConfig)
{
@@ -800,6 +880,26 @@
}
/* Initialize SBR parameters */
+ if ( (hAacConfig->audioObjectType==AOT_ER_AAC_ELD)
+ && (config->userSbrEnabled == (UCHAR)-1) && (config->userSbrRatio==0) )
+ {
+ UINT eldSbr = 0;
+ UINT eldSbrRatio = 0;
+
+ if ( AACENC_OK!=(err=eldSbrConfigurator(
+ hAacConfig->sampleRate,
+ hAacConfig->channelMode,
+ hAacConfig->bitRate,
+ &eldSbr,
+ &eldSbrRatio)) )
+ {
+ return err;
+ }
+
+ hAacConfig->syntaxFlags |= ((eldSbr) ? AC_SBR_PRESENT : 0);
+ hAacConfig->sbrRatio = eldSbrRatio;
+ }
+ else
if ( (config->userSbrRatio==0) && (isSbrActive(hAacConfig)) ) {
/* Automatic SBR ratio configuration
* - downsampled SBR for ELD
