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Topic: HVXC

	Natural Speech Coding Tools
		HVXC is used at a low bitrate of 2 or 4 kbit/s.
		The frame length, the number of subframes per frame, and selection of the excitation codebook are modified for different bitrates [11].
		HVXC and CELP may be used to generate the core bitstream when the enhancement bitstreams are generated by TwinVQ or AAC.
	www.chiariglione.org /mpeg/tutorials/papers/icj-mpeg4-si/09-natural_audio_paper/speechtools.html (892 words)

	Harmonic Vector Excitation Coding - Wikipedia, the free encyclopedia
		Harmonic Vector Excitation Coding, abbreviated as HVXC is a speech coding algorithm used in MPEG-4 standard for very low bit rate speech coding.
		HVXC supports bitrates of 2 and 4 kbit/s.
		HVXC is a parametric speech codec, which in practise means that it is optimized for speech signals only.
	en.wikipedia.org /wiki/Harmonic_Vector_Excitation_Coding (105 words)

	Via Licensing
		The standard defines two HVXC bit rates: 2 kbps and 4 kbps.
		Unlike the code excited linear prediction (CELP) speech coder, HVXC is a parametric coding system, which means that certain aspects of the coded representation can be manipulated independently.
		HVXC is useful for a variety of synthetic speech applications in bandwidth-constrained environments.
	www.vialicensing.com /licensing/MPEG4_object_licenses.cfm?product=MPEG-4HVXC (119 words)

	Digital Radio Mondiale Audio Encoding (Site not responding. Last check: 2007-11-05)
		The current DRM specification allows the use of three audio encoding systems that provide audio in different qualities.
		The most commonly used one is AAC followed by CELP and then HVXC that is now being used in several live DRM transmissions.
		As of January 2006 HVXC is being tested by Croatia and two 26 MHz transmissions in London.
	www.radioeng.co.uk /drm-audio.html (58 words)

	Natural Speech Coding Tools (Site not responding. Last check: 2007-11-05)
		HVXC is used at a low bitrate of 2 or 4 kbit/s.
		The frame length, the number of subframes per frame, and selection of the excitation codebook are modified for different bitrates [11].
		HVXC and CELP may be used to generate the core bitstream when the enhancement bitstreams are generated by TwinVQ or AAC.
	telecom.inescn.pt /people/mandrade/tvd/2000/docs/GERAL/mp4-natural-audio/speechtools.html (719 words)

	audio (Site not responding. Last check: 2007-11-05)
		HVXC is telephone quality only (100 Hz to 3800 Hz) suitable for speech with an 8 kHz sampling rate.
		As DRM can support 4 services it is possible to have a separate audio voice being transmitted as well as the main audio/data service.
		The second audio service is using the HVXC speech audio codec.
	www.drmradio.co.uk /html/drm_audio_page.html (717 words)

	AudioCoding.com - Knowledge Base (Site not responding. Last check: 2007-11-05)
		MPEG-4 parametric speech coder uses Harmonic Vector eXcitation Coding (HVXC) algorithm where harmonic coding of LPC residual signals for voiced segments and Vector eXcitation Coding (VXC) for unvoiced segments are used.
		In Version 1 HVXC, variable bit-rate mode of 2.0 kbps maximum is supported as well as 2.0 and 4.0 kbps fixed bit-rate mode.
		When the variable bit-rate mode of 4.0 kbps maximum is used, the average bit rate goes down to approximately 3.0 kbps with typical speech items.
	www.audiocoding.com /modules/wiki?page=HVXC (431 words)

	Voice Conversion: Adaptation of relative local Speech Rate by MPEG-4 HVXC. (Site not responding. Last check: 2007-11-05)
		This paper proposes a modified speech coder, namely the MPEG-4 harmonic vector excitation coder (HVXC), for adaptation of the relative speech rate.
		Applied to the conversion of voice characteristics it can be used to partially restore the speaking style of a specific speaker which can get lost during the process of a frame-by-frame voice conversion.
		Furthermore, a method for estimation of the relative speech rate between two different speakers will be given.The results show that the speech rate can be adapted by the proposed system with almost no quality decrease of the synthesized speech.
	www-lns.tf.uni-kiel.de /publi/abstracts/LeHe02a.html (120 words)

	Overview of the MPEG-4 Standard (Site not responding. Last check: 2007-11-05)
		The Error Resilient (ER) HVXC object is supported by the Parametric speech coding (ER HVXC) tools, which provides fixed bit-rate modes(2.0-4.0kbps) and variable bit-rate mode(<2.0kbps, <4.0kbps) both in a scalable and non-scalable scheme.
		In the Version 1 HVXC, variable bit rate mode of 2.0 kbit/s maximum is already supported and the variable bit rate mode of 4.0 kbit/s maximum is additionally supported in Version 2 ER HVXC.
		ER HVXC has the syntax with the error sensitivity classes to be used with the EP-Tool, and the error concealment functionality are supported for the use for error-prone channel like mobile communication channels.
	library.n0i.net /graphics/mp-eg4_overview (17558 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		Code excited linear prediction(CELP), HVXC (harmonic vector eXcitation).
		In order to achieve the sound quality of FM signals, the AAC is extended by SPR (Spectral Band Replication).
		For example, the playback speed of a HVXC-encoded bit stream can be altered without affecting the pitch of the voice.
	myhome.spu.edu /krisman (1675 words)

	Citations: MPEG-4 speech coding - Nishiguchi (ResearchIndex) (Site not responding. Last check: 2007-11-05)
		The HVXC MPEG 4 vocoder results in high quality speech (sampled at 8 kHz) at very low bit rate: the 2 kbit s HVXC coder quality is comparable with that of the 4.
		HVXC CODER The HVXC coding scheme is depicted in Fig.
		The Linear Predictive Coding (LPC) block extracts the parameters of the autoregressive model.
	citeseer.ist.psu.edu /context/1408209/0 (390 words)

	DRM: Digital Radio Mondiale
		The DRM system uses MPEG 4 HE AAC v2 for mixed programming providing high quality at low data rates.
		In addition, CELP and HVXC coders are available to provide speech-only programming at even lower data rates.
		In 2005, the DRM Consortium decided to extend the DRM system to operate in all the broadcasting bands below 120 MHz.
	www.drm.org /system/technicalaspect.php (407 words)

	Ittiam \| Products \| Speech Codecs \| MPEG4 HVXC (Site not responding. Last check: 2007-11-05)
		Harmonic Vector Excitation Coding (HVXC) is part of MPEG-4 audio standard, and is used to code narrow band (8 kHz sample rate) speech at 2.0 or 4.0 kbps.
		This low bit rate coder has a very high coding efficiency (compression ratio of 64 @ 2kpbs) and the quality of the speech at 2kbps is better than FS-CELP at 4.8 kbps.
		The HVXC speech coder targets applications from mobile and satellite communications, to Internet telephony, to packaged media and speech databases.
	www.ittiam.com /pages/products/hvxc.htm (225 words)

	IBC 2002 Conference Papers (Site not responding. Last check: 2007-11-05)
		The test also impressively demonstrates the audio quality improvement, which can be achieved for low bit rates by combining AAC and mp3 with SBR.
		Parametric codecs such as HVXC (Harmonic Vector eXitation Coding) generally reach a point where addition of more bits within the existing coding scheme does not lead to any significant increase in subjective audio quality.
		However, the SBR method has turned out to be useful also together with speech codecs.
	www.broadcastpapers.com /radio/ibc2003CodingSBR03.htm (584 words)

	ETD-db: ETD database (Site not responding. Last check: 2007-11-05)
		Harmonic Detection and Estimation for HVXC Speech Coders
		In the HVXC speech coder, the pitch is an indispensable parameter for successful estimation of the harmonic magnitudes.
		Hence, we secondly propose a tree searching method to refine the estimated pitch.
	etdncku.lib.ncku.edu.tw /ETD-db/ETD-search/view_etd?URN=etd-0707103-093405 (146 words)

	HVXC - The DJ List
		You are in: Home → The DJ List → HVXC
		Join up and chat with music fans all over the world!
		Note that it requires an additional registration to join.
	www.thedjlist.com /djs/HVXC (30 words)

	Lutz Leutelt's Homepage
		MPEG-4 HVXC Speech Codec (Project in Cooperation with Industry)
		Survey of Implementation and Complexity Aspects of Fixed-point Harmonic Vector Excitation Coder (HVXC)
		Leutelt, L. An MPEG-4 HVXC Based Interspeaker Pitch Prediction for Voice Conversion.
	www-lns.tf.uni-kiel.de /staff/ll/pages/welcome_main.html (328 words)

	4 Hvxc Mpeg First of and more about 4 Hvxc Mpeg (Site not responding. Last check: 2007-11-05)
		4 Hvxc Mpeg First of and more about 4 Hvxc Mpeg
		JPEG, MP3 and MPEG-2/4 AAC Audio, and MPEG-4 HVXC Speech.
		HVXC Decoder is an implementation of MPEG-4 HVXC (Harmonic Vector Excitation Coding)...
	www.vid101.video-201.info /4-Hvxc-Mpeg.html (392 words)

	Ittiam \| Products \| Digital Media Solutions on StarCore (Site not responding. Last check: 2007-11-05)
		The suite includes decoders for MPEG-4 Simple Profile (SP) Video, JPEG, MP3 and MPEG-2/4 AAC Audio, and MPEG-4 HVXC Speech.
		The decoders are fine tuned to exploit the unique architectural features of the StarCore SC1200 and SC1400 DSP cores.
		HVXC Decoder is an implementation of MPEG-4 HVXC (Harmonic Vector Excitation Coding) speech decoder.
	www.ittiam.com /pages/products/starcore_dm.htm (560 words)

	Hydrogenaudio Forums > MPEG4-CELP (Site not responding. Last check: 2007-11-05)
		Jul 14 2003, 01:31 PM Hello on http://www.ittiam.com/ I found that there are the speech encoders MPEG4 CELP and MPEG4 HVXC and GSM-AMR - and there also is Ogg Speex.
		Does anyone know of freely downloadable MPEG4 CELP or HVXC encoders so I could do a comparison for different bitrates?
		Which speech encoder would be expected to have the best quality in for example the 8-16 Kbit/s range?
	www.hydrogenaudio.org /forums/lofiversion/index.php/t11344.html (302 words)

	DIGIDIA : DRM Content Server
		DRM audio encoding (AAC, CELP, HVXC with or without SBR)
		Data insertion (MOT Slide Show, MOT BWS, IP Tunnelling)
		AAC, CELP and HVXC audio encoding possibilities (with or without SBR)
	www.digidia.fr /Rubrique.aspx?RubriqueID=73&LangueID=2&PereID=65 (284 words)

	Fraunhofer IIS - Digital Broadcasting Systems - Fraunhofer DRM ContentServer (Site not responding. Last check: 2007-11-05)
		it is an AAC, AAC+SBR, (CELP, HVXC) real time encoder
		supports (if available) speech codes CELP, HVXC (low bitrates)
		Portions of Enhanced MPEG-4 AAC+SBR coding technology licensed by CodingTechnologies.
	www.iis.fraunhofer.de /dab/products/contentserver (1219 words)

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