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-rw-r--r--libAACenc/include/aacenc_lib.h45
-rw-r--r--libAACenc/src/aacenc_lib.cpp2
-rw-r--r--libAACenc/src/adj_thr.cpp8
-rw-r--r--libAACenc/src/bandwidth.cpp12
-rw-r--r--libAACenc/src/qc_main.cpp17
5 files changed, 36 insertions, 48 deletions
diff --git a/libAACenc/include/aacenc_lib.h b/libAACenc/include/aacenc_lib.h
index 01a9d36..71f7556 100644
--- a/libAACenc/include/aacenc_lib.h
+++ b/libAACenc/include/aacenc_lib.h
@@ -436,31 +436,32 @@ audio quality.
\subsection vbrmode Variable Bitrate Mode
-The encoder provides various Variable Bitrate Modes that differ in audio quality
-and average overall bitrate. The given values are averages over time, different
-encoder settings and strongly depend on the type of audio signal. The VBR
-configurations can be adjusted via ::AACENC_BITRATEMODE encoder parameter.
+The variable bitrate (VBR) mode coding adapts the bit consumption to the
+psychoacoustic requirements of the signal. The encoder ignores the user-defined
+bit rate and selects a suitable pre-defined configuration based on the provided
+AOT. The VBR mode 1 is tuned for HE-AACv2, for VBR mode 2, HE-AACv1 should be
+used. VBR modes 3-5 should be used with Low-Complexity AAC. When encoding
+AAC-ELD, the best mode is selected automatically.
+
+The bitrates given in the table are averages over time and different encoder
+settings. They strongly depend on the type of audio signal. The VBR
+configurations can be adjusted with the ::AACENC_BITRATEMODE encoder parameter.
\verbatim
---------------------------------------------
- VBR_MODE | Approx. Bitrate in kbps/channel
- | AAC-LC | AAC-LD/AC_ELD
-----------+---------------+-----------------
- VBR_1 | 32 - 48 | 32 - 56
- VBR_2 | 40 - 56 | 40 - 64
- VBR_3 | 48 - 64 | 48 - 72
- VBR_4 | 64 - 80 | 64 - 88
- VBR_5 | 96 - 120 | 112 - 144
+-----------------------------------------------
+ VBR_MODE | Approx. Bitrate in kbps for stereo
+ | AAC-LC | AAC-ELD
+----------+---------------+--------------------
+ VBR_1 | 32 (HE-AACv2) | 48
+ VBR_2 | 72 (HE-AACv1) | 56
+ VBR_3 | 112 | 72
+ VBR_4 | 148 | 148
+ VBR_5 | 228 | 224
--------------------------------------------
\endverbatim
-The bitrate ranges apply for individual audio channels. In case of multichannel
-configurations the average bitrate might be estimated by multiplying with the
-number of effective channels. This corresponds to all audio input channels
-exclusively the low frequency channel. At configurations which are making use of
-downmix modules the AAC core channels respectively downmix channels shall be
-considered. For ::AACENC_AOT which are using SBR, the average bitrate can be
-estimated by using the ratio of 0.5 for dualrate SBR and 0.75 for downsampled
-SBR configurations.
-
+Note that these figures are valid for stereo encoding only. VBR modes 2-5 will
+yield much lower bit rates when encoding single-channel input. For
+configurations which are making use of downmix modules the AAC core channels
+respectively downmix channels shall be considered.
\subsection encQual Audio Quality Considerations
The default encoder configuration is suggested to be used. Encoder tools such as
diff --git a/libAACenc/src/aacenc_lib.cpp b/libAACenc/src/aacenc_lib.cpp
index 15b06bd..2c2010f 100644
--- a/libAACenc/src/aacenc_lib.cpp
+++ b/libAACenc/src/aacenc_lib.cpp
@@ -110,7 +110,7 @@ amm-info@iis.fraunhofer.de
/* Encoder library info */
#define AACENCODER_LIB_VL0 4
#define AACENCODER_LIB_VL1 0
-#define AACENCODER_LIB_VL2 0
+#define AACENCODER_LIB_VL2 1
#define AACENCODER_LIB_TITLE "AAC Encoder"
#ifdef __ANDROID__
#define AACENCODER_LIB_BUILD_DATE ""
diff --git a/libAACenc/src/adj_thr.cpp b/libAACenc/src/adj_thr.cpp
index 226d003..239abd0 100644
--- a/libAACenc/src/adj_thr.cpp
+++ b/libAACenc/src/adj_thr.cpp
@@ -1302,14 +1302,6 @@ static void FDKaacEnc_reduceThresholdsVBR(
if (sfbThrReducedLdData < FL2FXCONST_DBL(-0.5f))
sfbThrReducedLdData = FL2FXCONST_DBL(-1.f);
- /* minimum of 29 dB Ratio for Thresholds */
- if ((sfbEnLdData + FL2FXCONST_DBL(1.0f)) >
- FL2FXCONST_DBL(9.6336206 / LD_DATA_SCALING)) {
- sfbThrReducedLdData = fixMax(
- sfbThrReducedLdData,
- sfbEnLdData - FL2FXCONST_DBL(9.6336206 / LD_DATA_SCALING));
- }
-
sfbThrReducedLdData = fixMax(MIN_LDTHRESH, sfbThrReducedLdData);
qcOutChan->sfbThresholdLdData[sfbGrp + sfb] = sfbThrReducedLdData;
diff --git a/libAACenc/src/bandwidth.cpp b/libAACenc/src/bandwidth.cpp
index 36cd64d..e814f05 100644
--- a/libAACenc/src/bandwidth.cpp
+++ b/libAACenc/src/bandwidth.cpp
@@ -1,7 +1,7 @@
/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android
-© Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
+© Copyright 1995 - 2019 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.
1. INTRODUCTION
@@ -151,11 +151,11 @@ typedef struct {
static const BANDWIDTH_TAB_VBR bandWidthTableVBR[] = {
{AACENC_BR_MODE_CBR, 0, 0},
- {AACENC_BR_MODE_VBR_1, 13050, 13050},
- {AACENC_BR_MODE_VBR_2, 13050, 13050},
- {AACENC_BR_MODE_VBR_3, 14260, 14260},
- {AACENC_BR_MODE_VBR_4, 15500, 15500},
- {AACENC_BR_MODE_VBR_5, 48000, 48000},
+ {AACENC_BR_MODE_VBR_1, 13000, 13000},
+ {AACENC_BR_MODE_VBR_2, 13000, 13000},
+ {AACENC_BR_MODE_VBR_3, 15750, 15750},
+ {AACENC_BR_MODE_VBR_4, 16500, 16500},
+ {AACENC_BR_MODE_VBR_5, 19293, 19293},
{AACENC_BR_MODE_SFR, 0, 0},
{AACENC_BR_MODE_FF, 0, 0}
diff --git a/libAACenc/src/qc_main.cpp b/libAACenc/src/qc_main.cpp
index ba3bc7e..bcfaa23 100644
--- a/libAACenc/src/qc_main.cpp
+++ b/libAACenc/src/qc_main.cpp
@@ -1,7 +1,7 @@
/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android
-© Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
+© Copyright 1995 - 2019 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.
1. INTRODUCTION
@@ -121,20 +121,15 @@ typedef struct {
static const TAB_VBR_QUAL_FACTOR tableVbrQualFactor[] = {
{QCDATA_BR_MODE_VBR_1,
- FL2FXCONST_DBL(0.160f)}, /* Approx. 32 - 48 (AC-LC), 32 - 56
- (AAC-LD/ELD) kbps/channel */
+ FL2FXCONST_DBL(0.150f)}, /* Approx. 32 kbps mono AAC-LC + SBR + PS */
{QCDATA_BR_MODE_VBR_2,
- FL2FXCONST_DBL(0.148f)}, /* Approx. 40 - 56 (AC-LC), 40 - 64
- (AAC-LD/ELD) kbps/channel */
+ FL2FXCONST_DBL(0.162f)}, /* Approx. 64 kbps stereo AAC-LC + SBR */
{QCDATA_BR_MODE_VBR_3,
- FL2FXCONST_DBL(0.135f)}, /* Approx. 48 - 64 (AC-LC), 48 - 72
- (AAC-LD/ELD) kbps/channel */
+ FL2FXCONST_DBL(0.176f)}, /* Approx. 96 kbps stereo AAC-LC */
{QCDATA_BR_MODE_VBR_4,
- FL2FXCONST_DBL(0.111f)}, /* Approx. 64 - 80 (AC-LC), 64 - 88
- (AAC-LD/ELD) kbps/channel */
+ FL2FXCONST_DBL(0.120f)}, /* Approx. 128 kbps stereo AAC-LC */
{QCDATA_BR_MODE_VBR_5,
- FL2FXCONST_DBL(0.070f)} /* Approx. 96 - 120 (AC-LC), 112 - 144
- (AAC-LD/ELD) kbps/channel */
+ FL2FXCONST_DBL(0.070f)} /* Approx. 192 kbps stereo AAC-LC */
};
static INT isConstantBitrateMode(const QCDATA_BR_MODE bitrateMode) {
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 11:11:56 +0000