| 词条 | Variable-Rate Multimode Wideband |
| 释义 |
|name = Variable-Rate Multimode Wideband (VMR-WB) |icon = |logo = |caption = |extension = |mime = audio/VMR-WB |type code = |uniform type = |magic = |owner = 3GPP2 |released = |latest release version = |latest release date = |genre = Audio compression format |containerfor = |containedby = 3G2, RTP |extendedfrom = AMR-WB/G.722.2 |extendedto = |standard = |url = 3GPP2 standards }} Variable-Rate Multimode Wideband (VMR-WB) is a source-controlled variable-rate multimode codec designed for robust encoding/decoding of wideband/narrowband speech. The operation of VMR-WB is controlled by speech signal characteristics (i.e., source-controlled) and by traffic condition of the network (i.e., network-controlled mode switching). Depending on the traffic conditions and the desired quality of service (QoS), one of the 4 operational modes is used. All operating modes of the existing VMR-WB standard are fully compliant with cdma2000 rate-set II. VMR-WB modes 0, 1, and 2 are cdma2000 native modes with mode 0 providing the highest quality and mode 2 the lowest ADR. VMR-WB mode 3 is the AMR-WB interoperable mode operating at an ADR slightly higher than mode 0 and providing a quality equal or better than that of AMR-WB at 12.65 kbit/s when in an interoperable interconnection with AMR-WB at 12.65 kbit/s. Now also a cdma2000 rate-set I compliant mode is implemented to the coder as mode 4. The average bitrate of the mode is 6.1 kbit/s (maximum is 8.55 kbit/s). Source coding bitrates are: Rate-Set I - 8.55, 4.0, 2.0, 0.8 kbit/s, Rate-Set II - 13.3, 6.2, 2.7, 1.0 kbit/s. VMR-WB uses 16 kHz sampling frequency.[1][2] Algorithmic delay is 33.75ms. VMR-WB can be also used in 3GPP2 container file format - 3G2. VMR-WB was designed by Nokia and VoiceAge. It is based on AMR-WB.[2] References1. ^{{citation |url=http://www.cablelabs.com/specifications/PKT-SP-CODEC-MEDIA-I07-090702.pdf |format=PDF |page=87 |title=PacketCable 2.0 - Codec and Media Specification - PKT-SP-CODEC-MEDIA-I07-090702 |year=2009 |accessdate=2011-06-23}} 2. ^1 {{citation|url=http://www.voiceage.com/vmrwb.php |title=VoiceAge website: VMR-WB — Source-controlled Variable Bit Rate Wideband Compression (archived) |date=2008-04-19 |accessdate=2011-06-23 |deadurl=yes |archiveurl=https://web.archive.org/web/20080419094934/http://www.voiceage.com/vmrwb.php |archivedate=April 19, 2008 }} External links
1 : Speech codecs |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。