question about the algorithm of AMR-WB |
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question about the algorithm of AMR-WB |
  Feb 22 2006, 06:32
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#1
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Group: Members Posts: 6 Joined: 22-February 06 Member No.: 27960  |
Hi,everbody:
I'm studing document of AMR-WB(G.722.2).I have found that there hasn't the post-processing in decoder. I know the technic of post prosessing which is supposed after reconstructing speech can improve the quality of reconstructed speech . In AMR-WB, there just has some process to adaptive codebook ， fixed codebook and gains. Dose anybody can help me about why AMR-WB needn't post-processing ? |
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Feb 23 2006, 11:08
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#2
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 Group: Developer Posts: 1245 Joined: 16-December 02 From: Australia Member No.: 4097 |
It's quite possible that they didn't put post-processing into AMR-WB standard. I don't have the technical specs with me at the moment so I'll check them tomorrow.
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 Feb 24 2006, 04:04
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#3
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Group: Members Posts: 6 Joined: 22-February 06 Member No.: 27960 |
amr-wb is mainly used for wireless communication, right? in addition, for wideband.
I have read some papars, and found that most narrowband communication use post processing, but for wb, they just adjust the gain in CLEP Does it have some relation to bandwidth? |
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Feb 24 2006, 04:42
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#4
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Group: Members Posts: 113 Joined: 28-December 05 Member No.: 26686 |
QUOTE (hengheng1981 @ Feb 21 2006, 11:32 PM) I'm studing document of AMR-WB(G.722.2).I have found that there hasn't the post-processing in decoder. I know the technic of post prosessing which is supposed after reconstructing speech can improve the quality of reconstructed speech . What post processing technic do you mean? 
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Feb 24 2006, 07:04
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#5
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Group: Members Posts: 6 Joined: 22-February 06 Member No.: 27960 |
a processing aims at background noise
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Feb 26 2006, 04:46
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#6
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Group: Members Posts: 113 Joined: 28-December 05 Member No.: 26686 |
QUOTE (hengheng1981 @ Feb 24 2006, 12:04 AM) a processing aims at background noise  Most probably, you will have no problem in adding additional processing at the decoder. |
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Mar 1 2006, 00:12
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#7
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Group: Developer Posts: 1245 Joined: 16-December 02 From: Australia Member No.: 4097 |
QUOTE (kwwong @ Feb 24 2006, 01:42 PM) QUOTE (hengheng1981 @ Feb 21 2006, 11:32 PM) I'm studing document of AMR-WB(G.722.2).I have found that there hasn't the post-processing in decoder. I know the technic of post prosessing which is supposed after reconstructing speech can improve the quality of reconstructed speech . What post processing technic do you mean? Most post-processing in CELP coders involve cascading a long-term and short-term postfilter as well as compensating for gain and reducing spectral tilt. The short-term postfilter emphasises formant peaks and attenuates spectral valleys between formants, while the long-term postfilter emphasises pitch harmonics. It makes the reconstructed speech sound better. As to why they haven't applied it to wideband coding, I'm not too sure. Perhaps, the existing AMR-WB didn't suffer from the quality problems of narrowband CELP. (and I seem to have forgotten to look up the tech specs, as promised in my earlier post lol) |
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Mar 2 2006, 01:10
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#8
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Group: Developer Posts: 1245 Joined: 16-December 02 From: Australia Member No.: 4097 |
OK, now browsing the tech specs of AMR-WB decoding. There is some post-processing in the lower bitrate modes (6.60 and 8.85 kbps) such as anti-sparseness processing, noise enhancement, pitch enhancement, etc.
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Lo-Fi Version | Time is now: 24th May 2013 - 22:33 |
