Then going for the latest encoders version via CoreAudioToolbox.dll v7.9.3.0 we get the higher bitrates for TVBR but are stuck with the lowpass bug for 96 Kbps encodes?
EDIT: Installing QT v7.7 and placing CoreAudioToolbox.dll v7.9.3.0 in qtaacenc's directory my system reports the latest QuickTime CoreFoundation library (QTCF.dll) v7.70.80.34 is being used and qtaacenc outputs "Using QuickTime 7.7.0 (LC-AAC encoder 1.7.2, HE-AAC encoder 1.2.1)", is that the ideal setup or is it just the CoreAudioToolbox library the one that matters?
EDIT2: D:\TEST\qtaacenc-20110816>qtaacenc.exe --tvbr 46 --highest --samplerate keep TEST.wav TEST96QT768.m4a
Using QuickTime 7.7.0 (LC-AAC encoder 1.7.2, HE-AAC encoder 1.2.1)
Configurations: True VBR quality 46, Highest quality profile, keep Hz
Progress: 100%
D:\TEST\qtaacenc-20110816>mediainfo TEST96QT768.m4a
General
Complete name : TEST96QT768.m4a
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 2.11 MiB
Duration : 2mn 47s
Overall bit rate : 106 Kbps
Encoded date : UTC 2011-08-29 13:11:39
Tagged date : UTC 2011-08-29 13:11:39
Writing application : qtaacenc 20110816, QuickTime 7.7.0, True VBR Quality 46
Encoding Params : (Binary)
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 47s
Bit rate mode : Variable
Bit rate : 104 Kbps
Maximum bit rate : 130 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 2.07 MiB (98%)
Language : English
Encoded date : UTC 2011-08-29 13:11:29
Tagged date : UTC 2011-08-29 13:11:39
D:\TEST\qtaacenc-20110816>qtaacenc.exe --tvbr 46 --highest --samplerate keep TEST.wav TEST96QT770.m4a
Using QuickTime 7.7.0 (LC-AAC encoder 1.7.1, HE-AAC encoder 1.2.0)
Configurations: True VBR quality 46, Highest quality profile, keep Hz
Progress: 100%
D:\TEST\qtaacenc-20110816>mediainfo TEST96QT770.m4a
General
Complete name : TEST96QT770.m4a
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 1.98 MiB
Duration : 2mn 47s
Overall bit rate : 99.0 Kbps
Encoded date : UTC 2011-08-29 13:12:23
Tagged date : UTC 2011-08-29 13:12:23
Writing application : qtaacenc 20110816, QuickTime 7.7.0, True VBR Quality 46
Encoding Params : (Binary)
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 47s
Bit rate mode : Variable
Bit rate : 96.0 Kbps
Maximum bit rate : 125 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 1.93 MiB (98%)
Language : English
Encoded date : UTC 2011-08-29 13:12:14
Tagged date : UTC 2011-08-29 13:12:23
Bit rates differ but sampling rates don't, does it mean the lowpass was not performed?
EDIT3: D:\TEST\qtaacenc-20110816>qtaacenc.exe --tvbr 40 --highest TEST.wav TEST_Q40_QT768_NoKeep.m4a
Using QuickTime 7.7.0 (LC-AAC encoder 1.7.2, HE-AAC encoder 1.2.1)
Configurations: True VBR quality 40, Highest quality profile, auto Hz
Progress: 100%
D:\TEST\qtaacenc-20110816>mediainfo TEST_Q40_QT768_NoKeep.m4a
General
Complete name : TEST_Q40_QT768_NoKeep.m4a
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 1.70 MiB
Duration : 2mn 47s
Overall bit rate : 85.0 Kbps
Encoded date : UTC 2011-08-29 14:05:03
Tagged date : UTC 2011-08-29 14:05:03
Writing application : qtaacenc 20110816, QuickTime 7.7.0, True VBR Quality 40
Encoding Params : (Binary)
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 47s
Bit rate mode : Variable
Bit rate : 83.4 Kbps
Maximum bit rate : 121 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 32.0 KHz
Compression mode : Lossy
Stream size : 1.66 MiB (98%)
Language : English
Encoded date : UTC 2011-08-29 14:04:54
Tagged date : UTC 2011-08-29 14:05:03
D:\TEST\qtaacenc-20110816>qtaacenc.exe --tvbr 40 --highest TEST.wav TEST_Q40_QT770_NoKeep.m4a
Using QuickTime 7.7.0 (LC-AAC encoder 1.7.1, HE-AAC encoder 1.2.0)
Configurations: True VBR quality 40, Highest quality profile, auto Hz
Progress: 100%
D:\TEST\qtaacenc-20110816>mediainfo TEST_Q40_QT770_NoKeep.m4a
General
Complete name : TEST_Q40_QT770_NoKeep.m4a
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 1.50 MiB
Duration : 2mn 47s
Overall bit rate : 75.1 Kbps
Encoded date : UTC 2011-08-29 14:00:42
Tagged date : UTC 2011-08-29 14:00:42
Writing application : qtaacenc 20110816, QuickTime 7.7.0, True VBR Quality 40
Encoding Params : (Binary)
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 47s
Bit rate mode : Variable
Bit rate : 73.5 Kbps
Maximum bit rate : 105 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 32.0 KHz
Compression mode : Lossy
Stream size : 1.47 MiB (98%)
Language : English
Encoded date : UTC 2011-08-29 14:00:32
Tagged date : UTC 2011-08-29 14:00:42
@ IgorC: both CoreAudioToolbox.dll v7.9.3.0 and CoreAudioToolbox.dll v7.9.7.3 behave identically towards Steve Forte Rio's founding of Steve Forte Rio's post #145, is that the lowpass bug you're referring to please?
Also, sorry if I'm maybe spamming a bit, just trying to understand what's the best/proper setup.