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
ITUT G729 preprocessing question
Started by ●April 29, 2009
Reply by ●May 4, 20092009-05-04
Reply by ●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 ●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 ●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 ●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.comBefore 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 ●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 ●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 ●May 6, 20092009-05-06
HyeeWang wrote: ...> 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. �����������������������������������������������������������������������
