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Topic: Personal blind listening test – MultiCodec at ~192 VBR kbps (Read 5512 times) previous topic - next topic
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Re: Personal blind listening test – MultiCodec at ~192 VBR kbps

Reply #50
Just a quick note that the updated FDK AAC settings/tunings in the software I use has been released. Good to see that they’ve been working with Exhale too. I’d love to give it a serious listening test myself but due to the pandemic I don’t currently have the equipment at this high bit rate. https://www.poikosoft.com/music-converter-version-history

Re: Personal blind listening test – MultiCodec at ~192 VBR kbps

Reply #51
Has something changed between FDK AAC 4.0.0 and 4.0.1? With 4.0.0 there's no Q10 VBR. There are 5 VBR mode for LC-AAC: the fourth one is ≃ 136 kbps and the next, fifth and last VBR mode is ≃ 236 kbps. Not very flexible and no ~192 kbps VBR mode with 4.0.0.
>source<.


I wonder what is the reason for the huge jump in bitrate between 4 & 5?!

Re: Personal blind listening test – MultiCodec at ~192 VBR kbps

Reply #52
Hello,

I wonder what is the reason for the huge jump in bitrate between 4 & 5?!

It seems to be designed like this,
Code: [Select]
libAACenc/include/aacenc_lib.h

-----------------------------------------------
 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
--------------------------------------------
perhaps to accommodate the (superfluous) bandwidth.
Code: [Select]
libAACenc/src/bandwidth.cpp

static const BANDWIDTH_TAB_VBR bandWidthTableVBR[] = {
    {AACENC_BR_MODE_CBR, 0, 0},
    {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}

    AiZ

Re: Personal blind listening test – MultiCodec at ~192 VBR kbps

Reply #53
Hello,

I wonder what is the reason for the huge jump in bitrate between 4 & 5?!

It seems to be designed like this,
Code: [Select]
libAACenc/include/aacenc_lib.h

-----------------------------------------------
 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
--------------------------------------------
perhaps to accommodate the (superfluous) bandwidth.
Code: [Select]
libAACenc/src/bandwidth.cpp

static const BANDWIDTH_TAB_VBR bandWidthTableVBR[] = {
    {AACENC_BR_MODE_CBR, 0, 0},
    {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}

    AiZ

I read the code but I still don't understand what does "to accommodate the (superfluous) bandwidth" mean?

 
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