> I have recognized that the operation of pre-emphasize can make the
> spectrum curve flatness,thus reduce the dynamic range in time domain.
> With the matlab srcipt, I performed a simple pre-emphasize algo and
> confirmed that.
Interesting!
> Jerry, you said "When bass is removed, there is less signal to encode,
> and usually a smaller dynamic range. "
>
> I know Bass is the section of low frequency components. but I do not
> know the exact frequency range of bass contained.It must be not the
> biggest item (800 HZ or so). Since Bass is neither the smallest
> elements or the biggest , how can removing BASS reduce the dynamic
> range?
"Bass" is the lower end of the spectrum you deal with. There is no
precise dividing line. (On keyboard instruments, it is often considered
to be what the left hand plays.) For voice intelligibility and speaker
recognition, there's little need for frequencies below 300 Hz, although
reproduction quality improves noticeably when an octave lower is
included. (Standard telephones are typically limited to a range of 300
to 3000 Hz.)
As for dynamic range, the sum of the bass and other amplitudes often
exceeds that of the others alone.
> thank you all for kind explanation.
You're welcome.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by HyeeWang●May 6, 20092009-05-06
On May 6, 12:53�am, Jerry Avins <j...@ieee.org> wrote:
> HyeeWang wrote:
> > On May 4, 9:12 pm, Jerry Avins <j...@ieee.org> wrote:
> >> HyeeWang wrote:
> >>> steveu,thank you.
> >>> 1. Removing DC is reasonable,for it is not a part of speech at all.But
> >>> what is the reason to remove bass?
> >> Bass can contain a lot of power, but adds little to intelligibility.
>
> >>> � How and why it can optimise the performance ? �
> >> By removing bass, more power it available for the most effective
> >> frequencies.
>
> >>> We should be to noted that G729 is not a waveform �coder,not
> >>> � a frequency domain waveform coder also, it is a parameter vocoder.
> >> Noted. So?
>
> >>> 2. G711, as an elementary coder algo, �use the basic A/mu law
> >>> nonuniform PCM quantization. I wonder whether it
> >>> � �can be called "codec". �How it can be dramatically improves the
> >>> quality?
> >> By providing 12 bits of dynamic range with an 8-bit system.
>
> >>> Vladimir Vassilevsky. Thank you.
> >>> G.711, G.721, two elementary coding algo, use basic A/mu law
> >>> nonuniform PCM quantization and ADPCM.
> >>> They all use waveform to compress data. It is nothing about frequency
> >>> domain. Why you wanna use a
> >>> fixed preemphasis/deemphasis in them? How u expect it work?
> >> Preemphasis "whitens" the signal, improving SNR.
>
> >> Jerry
> >> --
> >> Engineering is the art of making what you want from things you can get.
> >> �����������������������������������������������������������������������
>
> > erry.Thank you.
>
> > Thank you for your graceful description about bass . Thus I get that
> > bass components occupy more in power,but contribute less in
> > intelligibility
>
> > 1.If in a frequency wavefrom coder,such as mp3/aac, �removing bass
> > must improve intelligibility. It is resonable for it can give more
> > attention/bits to that effective for intelligibility.
>
> > But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
> > model and analyse LPC parameter/pitch. It is not a wavefrom coder.
> > Removing bass �can not work.
>
> Think again!
>
> > Can the operation of removing Bass make the LPC coefficients/Pitch
> > more effective?
>
> Sure. Removing the bass range means that there are fewer pitches to
> encode. Think of bass as similar to font information in text in a word
> processor. Removing it makes the presentation less pretty, but not much
> less intelligible.
>
> > 2. G711,although it is a waveform coder,but it operate in time
> > domain,not in frequency � domain. Removing bass can not work also, for
> > BASS is a characteristic of frequency.
>
> When bass is removed, there is less signal to encode, and usually a
> smaller dynamic range.
>
> > 3. Preemphasis "whitens" the signal, improving SNR. It did and made
> > spectrum curve more flat.Thus raising SNR is right. But G711/G721
> > (nonuniform PCM and ADPCM) is operating in time domain. The large SNR
> > in frequency sense can give rise to large SNR in time sense?
>
> > Thank you for your reply.
>
> For what it's worth. Anyhow, you're quite welcome.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> �����������������������������������������������������������������������- Hide quoted text -
>
> - Show quoted text -
I have recognized that the operation of pre-emphasize can make the
spectrum curve flatness,thus reduce the dynamic range in time domain.
With the matlab srcipt, I performed a simple pre-emphasize algo and
confirmed that.
Jerry, you said "When bass is removed, there is less signal to encode,
and usually a
smaller dynamic range. "
I know Bass is the section of low frequency components. but I do not
know the exact frequency range of bass contained.It must be not the
biggest item (800 HZ or so). Since Bass is neither the smallest
elements or the biggest , how can removing BASS reduce the dynamic
range?
thank you all for kind explanation.
HyeeWang
Reply by Jerry Avins●May 5, 20092009-05-05
HyeeWang wrote:
> On May 4, 9:12 pm, Jerry Avins <j...@ieee.org> wrote:
>> HyeeWang wrote:
>>> steveu,thank you.
>>> 1. Removing DC is reasonable,for it is not a part of speech at all.But
>>> what is the reason to remove bass?
>> Bass can contain a lot of power, but adds little to intelligibility.
>>
>>> How and why it can optimise the performance ?
>> By removing bass, more power it available for the most effective
>> frequencies.
>>
>>> We should be to noted that G729 is not a waveform coder,not
>>> a frequency domain waveform coder also, it is a parameter vocoder.
>> Noted. So?
>>
>>> 2. G711, as an elementary coder algo, use the basic A/mu law
>>> nonuniform PCM quantization. I wonder whether it
>>> can be called "codec". How it can be dramatically improves the
>>> quality?
>> By providing 12 bits of dynamic range with an 8-bit system.
>>
>>> Vladimir Vassilevsky. Thank you.
>>> G.711, G.721, two elementary coding algo, use basic A/mu law
>>> nonuniform PCM quantization and ADPCM.
>>> They all use waveform to compress data. It is nothing about frequency
>>> domain. Why you wanna use a
>>> fixed preemphasis/deemphasis in them? How u expect it work?
>> Preemphasis "whitens" the signal, improving SNR.
>>
>> Jerry
>> --
>> Engineering is the art of making what you want from things you can get.
>> �����������������������������������������������������������������������
>
> erry.Thank you.
>
> Thank you for your graceful description about bass . Thus I get that
> bass components occupy more in power,but contribute less in
> intelligibility
>
> 1.If in a frequency wavefrom coder,such as mp3/aac, removing bass
> must improve intelligibility. It is resonable for it can give more
> attention/bits to that effective for intelligibility.
>
> But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
> model and analyse LPC parameter/pitch. It is not a wavefrom coder.
> Removing bass can not work.
Think again!
> Can the operation of removing Bass make the LPC coefficients/Pitch
> more effective?
Sure. Removing the bass range means that there are fewer pitches to
encode. Think of bass as similar to font information in text in a word
processor. Removing it makes the presentation less pretty, but not much
less intelligible.
> 2. G711,although it is a waveform coder,but it operate in time
> domain,not in frequency domain. Removing bass can not work also, for
> BASS is a characteristic of frequency.
When bass is removed, there is less signal to encode, and usually a
smaller dynamic range.
> 3. Preemphasis "whitens" the signal, improving SNR. It did and made
> spectrum curve more flat.Thus raising SNR is right. But G711/G721
> (nonuniform PCM and ADPCM) is operating in time domain. The large SNR
> in frequency sense can give rise to large SNR in time sense?
>
>
> Thank you for your reply.
For what it's worth. Anyhow, you're quite welcome.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Sebastian Doht●May 5, 20092009-05-05
HyeeWang schrieb:
> On May 5, 5:02 pm, HyeeWang <hyeew...@gmail.com> wrote:
>> On May 4, 9:12 pm, Jerry Avins <j...@ieee.org> wrote:
>>
>>
>>
>>
>>
>>> HyeeWang wrote:
>>>> steveu,thank you.
>>>> 1. Removing DC is reasonable,for it is not a part of speech at all.But
>>>> what is the reason to remove bass?
>>> Bass can contain a lot of power, but adds little to intelligibility.
>>>> How and why it can optimise the performance ?
>>> By removing bass, more power it available for the most effective
>>> frequencies.
>>>> We should be to noted that G729 is not a waveform coder,not
>>>> a frequency domain waveform coder also, it is a parameter vocoder.
>>> Noted. So?
>>>> 2. G711, as an elementary coder algo, use the basic A/mu law
>>>> nonuniform PCM quantization. I wonder whether it
>>>> can be called "codec". How it can be dramatically improves the
>>>> quality?
>>> By providing 12 bits of dynamic range with an 8-bit system.
>>>> Vladimir Vassilevsky. Thank you.
>>>> G.711, G.721, two elementary coding algo, use basic A/mu law
>>>> nonuniform PCM quantization and ADPCM.
>>>> They all use waveform to compress data. It is nothing about frequency
>>>> domain. Why you wanna use a
>>>> fixed preemphasis/deemphasis in them? How u expect it work?
>>> Preemphasis "whitens" the signal, improving SNR.
>>> Jerry
>>> --
>>> Engineering is the art of making what you want from things you can get.
>>> �����������������������������������������������������������������������
>> erry.Thank you.
>>
>> Thank you for your graceful description about bass . Thus I get that
>> bass components occupy more in power,but contribute less in
>> intelligibility
>>
>> 1.If in a frequency wavefrom coder,such as mp3/aac, removing bass
>> must improve intelligibility. It is resonable for it can give more
>> attention/bits to that effective for intelligibility.
>>
>> But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
>> model and analyse LPC parameter/pitch. It is not a wavefrom coder.
>> Removing bass can not work.
>> Can the operation of removing Bass make the LPC coefficients/Pitch
>> more effective?
>>
>> 2. G711,although it is a waveform coder,but it operate in time
>> domain,not in frequency domain. Removing bass can not work also, for
>> BASS is a characteristic of frequency.
>>
>> 3. Preemphasis "whitens" the signal, improving SNR. It did and made
>> spectrum curve more flat.Thus raising SNR is right. But G711/G721
>> (nonuniform PCM and ADPCM) is operating in time domain. The large SNR
>> in frequency sense can give rise to large SNR in time sense?
>>
>> Thank you for your reply.
>>
>> Regards
>> HyeeW...@gmail.com- Hide quoted text -
>>
>> - Show quoted text -
>
> Jerry.Thank you.
>
> Thank you for your graceful description about bass . Thus I get that
> bass components occupy more in power,but contribute less in
> intelligibility
>
> 1.If in a frequency wavefrom coder,such as mp3/aac, removing bass
> must improve intelligibility. It is resonable for it can give more
> attention/bits to that effective for intelligibility.
>
> But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
> model and analyse LPC parameter/pitch. It is not a wavefrom coder.
> Removing bass can not work.
> Can the operation of removing Bass make the LPC coefficients/Pitch
> more effective?
>
>
> 2. G711,although it is a waveform coder,but it operate in time
> domain,not in frequency domain. Removing bass can not work also, for
> BASS is a characteristic of frequency.
>
> 3. Preemphasis "whitens" the signal, improving SNR. It did and made
> spectrum curve more flat.Thus raising SNR is right. But G711/G721
> (nonuniform PCM and ADPCM) is operating in time domain. The large SNR
> in frequency sense can give rise to large SNR in time sense?
>
>
> Thank you for your reply.
>
> Regards
> HyeeWang@gmail.com
Before you are trying to understand a codec you should get hands on some
textbook like "Digital Communications" from Proakis, because you lack
some basics:
1. What can be done in the frequency domain can also be done in the time
domain. It depends on the computational costs which domain should be
choosen.
2. SNR is defined as the ratio of signal power to noise power.
Therefore it is not a question of time or frequency (see theorem of
parseval)
Sebastian
Reply by HyeeWang●May 5, 20092009-05-05
On May 5, 5:02�pm, HyeeWang <hyeew...@gmail.com> wrote:
> On May 4, 9:12�pm, Jerry Avins <j...@ieee.org> wrote:
>
>
>
>
>
> > HyeeWang wrote:
> > > steveu,thank you.
>
> > > 1. Removing DC is reasonable,for it is not a part of speech at all.But
> > > what is the reason to remove bass?
>
> > Bass can contain a lot of power, but adds little to intelligibility.
>
> > > � How and why it can optimise the performance ? �
>
> > By removing bass, more power it available for the most effective
> > frequencies.
>
> > > We should be to noted that G729 is not a waveform �coder,not
> > > � a frequency domain waveform coder also, it is a parameter vocoder.
>
> > Noted. So?
>
> > > 2. G711, as an elementary coder algo, �use the basic A/mu law
> > > nonuniform PCM quantization. I wonder whether it
> > > � �can be called "codec". �How it can be dramatically improves the
> > > quality?
>
> > By providing 12 bits of dynamic range with an 8-bit system.
>
> > > Vladimir Vassilevsky. Thank you.
>
> > > G.711, G.721, two elementary coding algo, use basic A/mu law
> > > nonuniform PCM quantization and ADPCM.
>
> > > They all use waveform to compress data. It is nothing about frequency
> > > domain. Why you wanna use a
> > > fixed preemphasis/deemphasis in them? How u expect it work?
>
> > Preemphasis "whitens" the signal, improving SNR.
>
> > Jerry
> > --
> > Engineering is the art of making what you want from things you can get.
> > �����������������������������������������������������������������������
>
> erry.Thank you.
>
> Thank you for your graceful description about bass . Thus I get that
> bass components occupy more in power,but contribute less in
> intelligibility
>
> 1.If in a frequency wavefrom coder,such as mp3/aac, �removing bass
> must improve intelligibility. It is resonable for it can give more
> attention/bits to that effective for intelligibility.
>
> But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
> model and analyse LPC parameter/pitch. It is not a wavefrom coder.
> Removing bass �can not work.
> Can the operation of removing Bass make the LPC coefficients/Pitch
> more effective?
>
> 2. G711,although it is a waveform coder,but it operate in time
> domain,not in frequency � domain. Removing bass can not work also, for
> BASS is a characteristic of frequency.
>
> 3. Preemphasis "whitens" the signal, improving SNR. It did and made
> spectrum curve more flat.Thus raising SNR is right. But G711/G721
> (nonuniform PCM and ADPCM) is operating in time domain. The large SNR
> in frequency sense can give rise to large SNR in time sense?
>
> Thank you for your reply.
>
> Regards
> HyeeW...@gmail.com- Hide quoted text -
>
> - Show quoted text -
Jerry.Thank you.
Thank you for your graceful description about bass . Thus I get that
bass components occupy more in power,but contribute less in
intelligibility
1.If in a frequency wavefrom coder,such as mp3/aac, removing bass
must improve intelligibility. It is resonable for it can give more
attention/bits to that effective for intelligibility.
But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
model and analyse LPC parameter/pitch. It is not a wavefrom coder.
Removing bass can not work.
Can the operation of removing Bass make the LPC coefficients/Pitch
more effective?
2. G711,although it is a waveform coder,but it operate in time
domain,not in frequency domain. Removing bass can not work also, for
BASS is a characteristic of frequency.
3. Preemphasis "whitens" the signal, improving SNR. It did and made
spectrum curve more flat.Thus raising SNR is right. But G711/G721
(nonuniform PCM and ADPCM) is operating in time domain. The large SNR
in frequency sense can give rise to large SNR in time sense?
Thank you for your reply.
Regards
HyeeWang@gmail.com
Reply by HyeeWang●May 5, 20092009-05-05
On May 4, 9:12�pm, Jerry Avins <j...@ieee.org> wrote:
> HyeeWang wrote:
> > steveu,thank you.
>
> > 1. Removing DC is reasonable,for it is not a part of speech at all.But
> > what is the reason to remove bass?
>
> Bass can contain a lot of power, but adds little to intelligibility.
>
> > � How and why it can optimise the performance ? �
>
> By removing bass, more power it available for the most effective
> frequencies.
>
> > We should be to noted that G729 is not a waveform �coder,not
> > � a frequency domain waveform coder also, it is a parameter vocoder.
>
> Noted. So?
>
> > 2. G711, as an elementary coder algo, �use the basic A/mu law
> > nonuniform PCM quantization. I wonder whether it
> > � �can be called "codec". �How it can be dramatically improves the
> > quality?
>
> By providing 12 bits of dynamic range with an 8-bit system.
>
> > Vladimir Vassilevsky. Thank you.
>
> > G.711, G.721, two elementary coding algo, use basic A/mu law
> > nonuniform PCM quantization and ADPCM.
>
> > They all use waveform to compress data. It is nothing about frequency
> > domain. Why you wanna use a
> > fixed preemphasis/deemphasis in them? How u expect it work?
>
> Preemphasis "whitens" the signal, improving SNR.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> �����������������������������������������������������������������������
erry.Thank you.
Thank you for your graceful description about bass . Thus I get that
bass components occupy more in power,but contribute less in
intelligibility
1.If in a frequency wavefrom coder,such as mp3/aac, removing bass
must improve intelligibility. It is resonable for it can give more
attention/bits to that effective for intelligibility.
But, G729/G723.1,based on CELP, is a parameter vocoder. It use speech
model and analyse LPC parameter/pitch. It is not a wavefrom coder.
Removing bass can not work.
Can the operation of removing Bass make the LPC coefficients/Pitch
more effective?
2. G711,although it is a waveform coder,but it operate in time
domain,not in frequency domain. Removing bass can not work also, for
BASS is a characteristic of frequency.
3. Preemphasis "whitens" the signal, improving SNR. It did and made
spectrum curve more flat.Thus raising SNR is right. But G711/G721
(nonuniform PCM and ADPCM) is operating in time domain. The large SNR
in frequency sense can give rise to large SNR in time sense?
Thank you for your reply.
Regards
HyeeWang@gmail.com
Reply by Jerry Avins●May 4, 20092009-05-04
HyeeWang wrote:
> steveu,thank you.
>
> 1. Removing DC is reasonable,for it is not a part of speech at all.But
> what is the reason to remove bass?
Bass can contain a lot of power, but adds little to intelligibility.
> How and why it can optimise the performance ?
By removing bass, more power it available for the most effective
frequencies.
> We should be to noted that G729 is not a waveform coder,not
> a frequency domain waveform coder also, it is a parameter vocoder.
Noted. So?
> 2. G711, as an elementary coder algo, use the basic A/mu law
> nonuniform PCM quantization. I wonder whether it
> can be called "codec". How it can be dramatically improves the
> quality?
By providing 12 bits of dynamic range with an 8-bit system.
> Vladimir Vassilevsky. Thank you.
>
> G.711, G.721, two elementary coding algo, use basic A/mu law
> nonuniform PCM quantization and ADPCM.
>
> They all use waveform to compress data. It is nothing about frequency
> domain. Why you wanna use a
> fixed preemphasis/deemphasis in them? How u expect it work?
Preemphasis "whitens" the signal, improving SNR.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Vladimir Vassilevsky●May 4, 20092009-05-04
Get a basic book such as Rabiner & Schafer.
VLV
"HyeeWang" <hyeewang@gmail.com> wrote in message
news:63429614-6926-400d-8788-9801e42b4d28@x1g2000prh.googlegroups.com...
> steveu,thank you.
>
> 1. Removing DC is reasonable,for it is not a part of speech at all.But
> what is the reason to remove bass?
> How and why it can optimise the performance ? We should be to
> noted that G729 is not a waveform coder,not
> a frequency domain waveform coder also, it is a parameter vocoder.
>
> 2. G711, as an elementary coder algo, use the basic A/mu law
> nonuniform PCM quantization. I wonder whether it
> can be called "codec". How it can be dramatically improves the
> quality?
>
> Vladimir Vassilevsky. Thank you.
>
> G.711, G.721, two elementary coding algo, use basic A/mu law
> nonuniform PCM quantization and ADPCM.
>
> They all use waveform to compress data. It is nothing about frequency
> domain. Why you wanna use a
> fixed preemphasis/deemphasis in them? How u expect it work?
>
> Any comments would be appreciated.
> HyeeWang@gmail.com
Reply by HyeeWang●May 4, 20092009-05-04
steveu,thank you.
1. Removing DC is reasonable,for it is not a part of speech at all.But
what is the reason to remove bass?
How and why it can optimise the performance ? We should be to
noted that G729 is not a waveform coder,not
a frequency domain waveform coder also, it is a parameter vocoder.
2. G711, as an elementary coder algo, use the basic A/mu law
nonuniform PCM quantization. I wonder whether it
can be called "codec". How it can be dramatically improves the
quality?
Vladimir Vassilevsky. Thank you.
G.711, G.721, two elementary coding algo, use basic A/mu law
nonuniform PCM quantization and ADPCM.
They all use waveform to compress data. It is nothing about frequency
domain. Why you wanna use a
fixed preemphasis/deemphasis in them? How u expect it work?
Any comments would be appreciated.
HyeeWang@gmail.com
Reply by Vladimir Vassilevsky●April 30, 20092009-04-30
"steveu" <steveu@coppice.org> wrote in message
news:N_-dnV-RhPr12mTUnZ2dnUVZ_tidnZ2d@giganews.com...
> >
> >
> >HyeeWang wrote:
> >
> >> 1. In the processing section of G729 spec, it says to apply a high
> >> pass filter with a cut-off frequency of 140 Hz.
> > Anyway the main purpose of this filter is removing
> >DC from the signal, so the frequency response is not critical.
>
> Its more than just an issue of removing DC. You need to remove the entire
> bass end of the spectrum to optimise the performance of the codec. This is
> true of most narrowband speech codecs. Even with an elementary codec like
> G.711, filtering below something like 200Hz dramatically improves how well
> the remainder of the signal codes.
I agree. There could be a lot of energy at low frequencies, however that
part is not very important for the perception of the speech. It only wastes
the bandwidth. Same idea applies to the power amplification.
What always surprised me in the G.711, G.721 and such: why didn't they use a
fixed preemphasis/deemphasis in the analog. It improves the quality very
noticeably.
Vladimir Vassilevsky
DSP and Mixed Signal Consultant
www.abvolt.com