# Qualcomm code-excited linear prediction

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Speech codec by Qualcomm

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Qualcomm PureVoice Filename extension .qcp Internet media type audio/qcelp Developed by Qualcomm Initial release 1994; 32 years ago (1994) Latest release TIA IS-733 December 1999; 26 years ago (1999-12) Type of format Lossy audio Open format? Yes Free format? No

**Qualcomm code-excited linear prediction** (**QCELP**), also known as **Qualcomm PureVoice**, is a [speech codec](/source/Speech_codec) developed in 1994 by [Qualcomm](/source/Qualcomm) to increase the speech quality of the [IS-96A](https://en.wikipedia.org/w/index.php?title=IS-96A&action=edit&redlink=1) codec earlier used in [CDMA](/source/Code-division_multiple_access) networks. It was later replaced with [EVRC](/source/Enhanced_Variable_Rate_Codec) to achieve better speech quality with fewer bits. The two versions, *QCELP8* and *QCELP13*, operate at 8 and 13 [kilobits per second](/source/Kilobits_per_second) (Kbit/s) respectively.

In [CDMA](/source/Code-division_multiple_access) systems, a QCELP [vocoder](/source/Vocoder) converts a sound signal into a signal transmissible within a circuit. In wired systems, voice signals are generally sampled at 8 kHz (that is, 8,000 sample values per second) and then encoded by 8-bit [quantization](/source/Quantization_(signal_processing)) for each sample value. Such a system transmits at 64 kbit/s, an expensive rate in a wireless system. A QCELP vocoder with variable rates can reduce the rate enough to fit a wireless system by [coding](/source/Line_coding) the information more efficiently. In particular, it can change its own coding rates based on the speaker's volume or pitch; a louder or higher-pitched voice requires a higher rate.

## References

- [https://web.archive.org/web/20130129041829/http://www.rfdh.com/ez/system/db/lib_jnl/upload/2489/](https://web.archive.org/web/20130129041829/http://www.rfdh.com/ez/system/db/lib_jnl/upload/2489/)[CSD9904]_QCELP_Vocoders_in_CDMA_Systems_Design.pdf

- [Archived PureVoice encoder and player downloads](https://www.rarewares.org/rrw/purevoice.php)

v t e Multimedia compression and container formats Video compression ISO, IEC, MPEG DV MJPEG Motion JPEG 2000 MPEG-1 MPEG-2 Part 2 MPEG-4 Part 2 / ASP Part 10 / AVC Part 33 / IVC MPEG-H Part 2 / HEVC MPEG-I Part 3 / VVC MPEG-5 Part 1 / EVC Part 2 / LCEVC ITU-T, VCEG H.120 H.261 H.262 H.263 H.264 / AVC H.265 / HEVC H.266 / VVC H.267 / Enhanced Compression Model SMPTE VC-1 VC-2 VC-3 VC-5 VC-6 TrueMotion and AOMedia TrueMotion S VP3 VP6 VP7 VP8 VP9 AV1 AV2 Chinese Standard AVS1 P2/AVS+ (GB/T 20090.2/16) AVS2 P2 (GB/T 33475.2,GY/T 299.1) HDR Vivid (GY/T 358) AVS3 P2 (GY/T 368) Others Apple Video AVS Bink Cinepak Daala DVI FFV1 Huffyuv Indeo Lagarith Microsoft Video 1 MSU Lossless OMS Video Pixlet ProRes 422 4444 QuickTime Animation Graphics RealVideo RTVideo SheerVideo Smacker Sorenson Video/Spark Theora Thor Ut WMV XEB YULS Audio compression ISO, IEC, MPEG MPEG-1 Layer II Multichannel MPEG-1 Layer I MPEG-1 Layer III (MP3) AAC HE-AAC AAC-LD MPEG Surround MPEG-4 ALS MPEG-4 SLS MPEG-4 DST MPEG-4 HVXC MPEG-4 CELP MPEG-D USAC MPEG-H 3D Audio ITU-T G.711 A-law µ-law G.718 G.719 G.722 G.722.1 G.722.2 G.723 G.723.1 G.726 G.728 G.729 G.729.1 IETF Opus iLBC Speex Vorbis FLAC 3GPP AMR AMR-WB AMR-WB+ EVRC EVRC-B EVS GSM-HR GSM-FR GSM-EFR ETSI AC-3 AC-4 DTS Bluetooth SIG SBC LC3 Chinese Standard AVS1 P10 (GB/T 20090.10) AVS2 P3 (GB/T 33475.3) Audio Vivid (GY/T 363) DRA (GB/T 22726) ExAC (SJ/T 11299.4) Others ACELP ALAC Asao ATRAC CELT Codec 2 iSAC Lyra MELP Monkey's Audio MT9 Musepack OptimFROG OSQ QCELP RCELP RealAudio SD2 SHN SILK Siren SMV SVOPC TTA True Audio TwinVQ VMR-WB VSELP WavPack WMA MQA aptX aptX HD aptX Low Latency aptX Adaptive LDAC LHDC LLAC TrueHD Image compression IEC, ISO, IETF, W3C, ITU-T, JPEG CCITT Group 4 GIF HEIC / HEIF HEVC JBIG JBIG2 JPEG JPEG 2000 JPEG-LS JPEG XL JPEG XR JPEG XS JPEG XT PNG APNG TIFF TIFF/EP TIFF/IT Others AV1 AVIF BPG DjVu EXR FLIF ICER MNG PGF QOI QTVR WBMP WebP Containers ISO, IEC MPEG-ES MPEG-PES MPEG-PS MPEG-TS ISO/IEC base media file format MPEG-4 Part 14 (MP4) Motion JPEG 2000 MPEG-21 Part 9 MPEG media transport ITU-T H.222.0 T.802 IETF RTP Ogg Matroska SMPTE GXF MXF Others 3GP and 3G2 AMV ASF AIFF AVI AU BPG Bink Smacker BMP DivX Media Format EVO Flash Video HEIF IFF M2TS Matroska WebM QuickTime File Format RatDVD RealMedia RIFF WAV MOD and TOD VOB, IFO and BUP Collaborations NETVC MPEG LA Alliance for Open Media Methods Entropy Arithmetic Huffman Modified LPC ACELP CELP LSP WLPC Lossless Lossy LZ DEFLATE LZW PCM A-law µ-law ADPCM DPCM Transforms DCT FFT MDCT Wavelet Daubechies DWT Lists Comparison of audio coding formats Comparison of video codecs List of codecs See Compression methods for techniques and Compression software for codecs

v t e Data compression software Archivers with compression (comparison) Free and open-source 7-Zip Ark Expander File Roller FreeArc Info-ZIP KGB Archiver PAQ pax PeaZip XAD (decompression only) Xarchiver Zipeg ZPAQ Freeware Filzip LHA StuffIt Expander (decompression only) The Unarchiver (decompression only) TUGZip ZipGenius Commercial ARC ALZip Archive Utility ARJ BetterZip MacBinary PKZIP/SecureZIP PowerArchiver StuffIt WinAce WinRAR WinZip Non-archiving compressors Generic bzip2 compress gzip lzip lzop pack rzip Snappy XZ Utils zstd For code UPX Audio compression (comparison) Lossy AAC Fraunhofer FDK AAC Nero AAC Codec FAAC Helix DNA Producer MP3 l3enc LAME TooLAME libavcodec libcelt libopus libspeex Musepack libvorbis Windows Media Encoder Lossless ALAC FLAC libavcodec Monkey's Audio mp4als OptimFROG Shorten WavPack Video compression (comparison) Lossy MPEG-4 ASP 3ivx DivX Nero Digital FFmpeg HDX4 Xvid H.264 CoreAVC Blu-code DivX FFmpeg Nero Digital OpenH264 QuickTime x264 HEVC DivX x265 Others CineForm Cinepak Daala DNxHD Helix DNA Producer Indeo libavcodec Schrödinger (Dirac) SBC Sorenson VP7 libtheora libvpx Windows Media Encoder Lossless FFV1 Huffyuv Lagarith MSU Lossless YULS See also: compression methods and compression formats

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Adapted from the Wikipedia article [Qualcomm code-excited linear prediction](https://en.wikipedia.org/wiki/Qualcomm_code-excited_linear_prediction) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Qualcomm_code-excited_linear_prediction?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.