search for: 200hz

Hi, The notch filter in AEC is only used to remove DC signal, and the time of convergence is not important, right? If so, I think preset value of notch_radius is too small, and it causes noticeable distortion(freq < 200hz cut). There is a picture in attachment to show signals under different radius in time-domain. By setting notch_radius to 0.999 for all sampling rates, I found better voice effect(distortion), while AEC still working fine. ????????QinBin ????????cola_tin at 163.com ??????????2010-03-03 -----...

Hi, But in fact, it really affects the voice quality. One of my tester says, "Is your mouth far way from the mic?" Could you explain why we should cut 200hz below? >The notch filter is specifically designed to cut below 200 Hz when >working in narrowband. In wideband, the cutoff is more around 50 Hz. The >reason is that in narrowband operation (irrespective of the codec), >you're not really supposed to have anything below ~200 Hz, b...

On 03/03/2010 10:22 PM, QianBin wrote: > Hi, > > But in fact, it really affects the voice quality. One of my tester says, "Is your mouth far way from the mic?" > Could you explain why we should cut 200hz below? > We already said it affects the quality when the voice is compressed. Are you asking why that should be? Even with a simple form of lightly lossy compression like alaw/ulaw, a big low frequency waveform can push the coder into using coarse steps, so the more interesting energy in the...

...010-03-03 02:40, brant wrote: > >> Hi, >> >> The notch filter in AEC is only used to remove DC signal, and the time of convergence is not important, right? >> If so, I think preset value of notch_radius is too small, and it causes noticeable distortion(freq< 200hz cut). >> There is a picture in attachment to show signals under different radius in time-domain. >> By setting notch_radius to 0.999 for all sampling rates, I found better voice effect(distortion), while AEC still >> working fine. >>

...get that. Jean-Marc On 2010-03-03 02:40, brant wrote: > Hi, > > The notch filter in AEC is only used to remove DC signal, and the time of convergence is not important, right? > If so, I think preset value of notch_radius is too small, and it causes noticeable distortion(freq< 200hz cut). > There is a picture in attachment to show signals under different radius in time-domain. > By setting notch_radius to 0.999 for all sampling rates, I found better voice effect(distortion), while AEC still > working fine. > > > > > ????????QinBin > ????????cola...

...2) Removing the noise: Before encoding some recorded sound with Speex, I run the sound through the FFT. Then it's a simple matter to loop over the frequency spectrum and subtract the noise profile. At this point it's also easy to do simple filtering, so I do a high-pass filter around 200Hz or so to get rid of unwanted bass. Then, I do the inverse FFT to get the sound back into the time domain, and I encode it with Speex. The noise is *greatly* reduced. The difference can really be dramatic. Drawbacks: Not all noise is regular over time, and this approach is a manual, non-adap...

...2) Removing the noise: Before encoding some recorded sound with Speex, I run the sound through the FFT. Then it's a simple matter to loop over the frequency spectrum and subtract the noise profile. At this point it's also easy to do simple filtering, so I do a high-pass filter around 200Hz or so to get rid of unwanted bass. Then, I do the inverse FFT to get the sound back into the time domain, and I encode it with Speex. The noise is *greatly* reduced. The difference can really be dramatic. Drawbacks: Not all noise is regular over time, and this approach is a manual, non-adap...

...e encoding some recorded sound with Speex, I > > run the sound through the FFT. Then it's a simple matter to loop over > the > frequency spectrum and subtract the noise profile. At this point it's > also easy to do simple filtering, so I do a high-pass filter around > 200Hz > or so to get rid of unwanted bass. Then, I do the inverse FFT to get > the > sound back into the time domain, and I encode it with Speex. The noise > is *greatly* reduced. The difference can really be dramatic. > > Drawbacks: Not all noise is regular over time, and this a...

..., 525, 0, > DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC | > DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK), > - .vrefresh = 120, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, > }, > + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, > /* 52 - 720x576 at 200Hz 4:3 */ > { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 108000, 720, 732, > 796, 864, 0, 576, 581, 586, 625, 0, > DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC), > - .vrefresh = 200, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, > }, > + .picture_aspect_...

...801, 858, 0, 480, 488, 494, 525, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK), - .vrefresh = 120, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, /* 52 - 720x576 at 200Hz 4:3 */ { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 108000, 720, 732, 796, 864, 0, 576, 581, 586, 625, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC), - .vrefresh = 200, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3...

...801, 858, 0, 480, 488, 494, 525, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK), - .vrefresh = 120, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, /* 52 - 720x576 at 200Hz 4:3 */ { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 108000, 720, 732, 796, 864, 0, 576, 581, 586, 625, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC), - .vrefresh = 200, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3...

...801, 858, 0, 480, 488, 494, 525, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK), - .vrefresh = 120, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, }, /* 52 - 720x576 at 200Hz 4:3 */ { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 108000, 720, 732, 796, 864, 0, 576, 581, 586, 625, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC), - .vrefresh = 200, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, }, + .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3...