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waveform interpolation coder with accurate reconstruction

Started by empush2000 September 21, 2003
Hi everyone,
I am currently working on waveform interpolative speech coding. I
exploit the usual scheme, but it doesn't provide accurate (perfect)
waveform reconstruction even when using no quantization. Does anyone
know any papers/info about perfect reconstruction for waveform
interpolation coder? Please advise.

Thank you.



Hi,

Unlike the speech coders from the CELP-family WI is a parametric
coder. The more bits you "invest" in CELP-like coder the higher
accuracy of the waveform reconstruction, but it is not so for WI. WI
strongly depends on pitch detection accuracy, CW-alignment and
CW-decomposition; if these procedures fail (completely or partially)
any amount of bits for SEW/REW quantization (including
non-quantization) will not help you. Even if in addition to
non-quantized SEW- and REW-amplitude spectra you transmit original
SEW- and REW-phase spectra (which is not interesting for commercial
WI) you still cannot get a perfect reconstruction of the waveform
because the initial phase in phase-tracking procedure is arbitraty.
So, don't judge your coder according to accuracy of the waveform
reconstruction. Try to focus on the following most annoying problems:
1. Good pitch detector
2. Good CW-alignment algorithm
3. Good CW-decomposition algorithm
For quality measurement use PESQ or PSQM. The following paper might
interest you:

C.H. Ritz, I.S. Burnett and J. Lukasiak, "Extending Waveform
Interpolation to Wideband Speech Coding", 2002 IEEE Speech Coding
Workshop.

Ilya Druker

--- In , "empush2000" <mpush2000@m...> wrote:
> Hi everyone,
> I am currently working on waveform interpolative speech coding. I
> exploit the usual scheme, but it doesn't provide accurate (perfect)
> waveform reconstruction even when using no quantization. Does anyone
> know any papers/info about perfect reconstruction for waveform
> interpolation coder? Please advise.
>
> Thank you.