Timhieu flac

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  • 1. Tm hiu Flac GVHD: Ths. Trn Nguyn Ngc Hc Vin: Nguyn Trng ip CB130029 Nguyn Thu Bch CB130017 H Ni 19/06/2014i Hc Bch Khoa H Ni 1

2. Ni dung Lch s u nhc im Thit k M ha nh dng So snh Cch s dng 2 3. Flac ( Free lossless audio codec) bt u pht trin nm 2000 bi Josh Coalson Pht hnh phin bn u tin 1.0 vo thng 7/2001 Thng 1/2003 Flac l d n ca Xiph.org Phin bn mi nht 1.3.0 pht hnh thng 5/2013 3 4. u im ca Flac Khng mt thng tin m thanh gc Kch thc tp tin ch bng 30- 60% so vi WAV Thi gian gii nn nhanh C kh nng sa li C th x l n 8 knh m thanh vm C th ti to li tp gc Chy trn hu ht cc thit b 4 5. Nhc im Cha h tr ht tt c cc thit b Dung lng file vn cn ln Cha c tch hp sn Cha stream trn internet 5 6. Thit k Gim 30-60% kch thc bn gc Ch h tr ly mu dy phy tnh C th s l bt k tp PCM no t 4-32 bit/ mu , ly mu t 1-655,350 hz ,bt k knh no t 1-8 knh S dng m CRC check li 6 7. M ha Flac theo cc bc sau: Chia khi: u vo c chia thnh nhiu block, mi block c kch thc khc nhau ph thuc nhiu yu t nh t l ly mu... Interchannel Decorrection: Trong trng hp m thanh stereo , b nn s to ra tn hiu gia da trn s khc bit gia 2 knh D on: cc block c a n b d on, b nn s tm mt thut ton m t. Thut ton m t ny nh hn nhiu tn hiu gc.b d on dng 4 phng php m hnh : verbatim , constant,c nh d on tuyn tnh,d on tuyn tnh FIR M ha phn cn li: nu b d on khng lm gim s bit 7 8. nh dng Mt bitstream Flac gm im nh du ban u flac trc mi stream H tr ln ti 128 khi siu d liu Bao gm nhiu khung m thanh.mi khung c tiu khung xc nh m ng b , tn s ly mu ,s knh... 8 9. 9 10. 10 11. So snh Flac vi cc nh dng khc Vi flac u im: m thanh chp lng cao, xp x cht lng gc , h tr a knh, vm, t ng sa sai Nhc im: kch thc ln, cha ph bin , tch hp 11 12. So snh Flac vi cc nh dng khc Vi mp3 u im: kch thc nh , d dng trnh din, tch hp nhiu thit b Nhc im: m thanh b mt thng tin , khng trnh din ng m thanh c trng nh ghita.. D dng stream trn internet 12 13. S dng Ngy nay mt s thit b media cao cp h tr Flac , cc phn mm play media thm code gii mi Flac nn vic trnh din Flac c m thanh cht lng cao rt d dng. Trn Windows phn mm Foorbar2000 c nh gi c kh nng gii m Flac chun v pht Flac hay nht 13 14. 14 Vi chun m thanh Lossless khc APE, M4A APE khng c cng ng pht trin Ra i sau Flac t ph bin M4A nh dng lossless ca apple M4A t thit b h tr, ch yu cc thit b apple 15. 15