MPEG4 AAC LD |
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MPEG4 AAC LD |
 Jan 19 2011, 13:36
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#1
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451  |
Can MPEG4 AAC LD be made from AAC LC by reducing its main 4 delays without using LTP?? or is LTP a major component in AAC-LD???
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Jan 19 2011, 17:47
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#2
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 Group: Members Posts: 4131 Joined: 2-September 02 Member No.: 3264 |
QUOTE (pratheekp @ Jan 19 2011, 07:36)  Can MPEG4 AAC LD be made from AAC LC by reducing its main 4 delays without using LTP?? or is LTP a major component in AAC-LD??? LTP is a dead and forgotten AAC extension. LD is the low delay profile for AAC. They're not really related. I don't know if its possible to use LTP with LD, but theres not much reason to want to. |
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Jan 20 2011, 05:34
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#3
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451 |
But in the MPEG4 spec its told that AAC-LD is the low delay profile for AAC-LTP....
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Jan 20 2011, 09:40
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#4
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451 |
Can any1 provide me good links for ER AAC-LD coding...thanx in advance...
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Jan 20 2011, 11:08
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#5
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451 |
delay in AAC-LC can be reduced using
1. 512/480 samples instead of 1024 2. No block switching 3. Filter bank delay 4. No(min) bit reservoir size But how can we achieve these conditions? |
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Jan 20 2011, 11:18
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#6
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Group: Members Posts: 73 Joined: 14-December 06 Member No.: 38681 |
Level for the Low Delay AAC Profile:
Max channels/object 2, Max sample rate 48kHz, epConfig 0 LTP is not permitted. Pulse data is not permited. QUOTE (pratheekp @ Jan 20 2011, 11:40) Can any1 provide me good links for ER AAC-LD coding...thanx in advance... search mpegif.org mailing lists |
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Jan 21 2011, 14:04
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#7
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451 |
I want to include LTP in ER AAC LD profile. I want to know whether LTP can be optionally enabled or is it mandatory every time. Also if mandatory why....and if not why...pls answer...
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Jan 21 2011, 20:16
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#8
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Group: Members Posts: 4131 Joined: 2-September 02 Member No.: 3264 |
QUOTE (pratheekp @ Jan 21 2011, 08:04) I want to include LTP in ER AAC LD profile. LTP is a dead format. You do not want to include it with anything. QUOTE (pratheekp @ Jan 21 2011, 08:04) I want to know whether LTP can be optionally enabled or is it mandatory every time. Also if mandatory why....and if not why...pls answer... According to the post above yours, it is not allowed. |
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Jan 21 2011, 21:56
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#9
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 Group: Developer Posts: 618 Joined: 6-December 08 From: Erlangen Germany Member No.: 64012 |
IIRC all AAC LD flavors are based on AAC Low Complexity (LC). LTP is not allowed in LC because it increases the decoder (and also encoder) complexity significantly. LTP needs quite a lot of computation for little gain on "real-world" natural audio material.
Chris -------------------- If I don't reply to your reply, it means I agree with you.
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Jan 24 2011, 09:09
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#10
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Group: Members Posts: 56 Joined: 19-January 11 Member No.: 87451 |
Thanks to all who responded...bt i juz want to know that if i'm including LTP...even though it may lead to larger computation...do i have the option to optionally enable/disable the tool as it is possible with other tools in AAC
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Jan 24 2011, 13:08
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#11
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Group: Members Posts: 73 Joined: 14-December 06 Member No.: 38681 |
QUOTE (C.R.Helmrich @ Jan 21 2011, 23:56) IIRC all AAC LD flavors are based on AAC Low Complexity (LC). LTP is not allowed in LC because it increases the decoder (and also encoder) complexity significantly. LTP needs quite a lot of computation for little gain on "real-world" natural audio material. Chris Decoding of LTP should not be computationally complex, what really makes AAC-LD decoder weird is ER related stuff like error-sensitivity categories and HCR. |
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Lo-Fi Version | Time is now: 20th May 2013 - 09:59 |
