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HDRオーディオを実装してみて思ったこと

 HDRオーディオを実装してみて思ったこと

IGDA SIG-Audio#02 (http://www.igda.jp/modules/bulletin/index.php?page=article&storyid=910) で使った資料です

スライドにある動画へのリンクは、以下になります。
41P
http://youtu.be/XBnQuLdzRNU

42P
http://youtu.be/wtw8aokE-aQ

43P
http://youtu.be/wPT76EPJFY8

Hattori_Yoshiaki

January 20, 2013
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  1. )%3ΦʔσΟΦΛ ࣮૷ͯ͠Θ͔ͬͨ͜ͱ ג ࣜ ձ ࣾ η Ψ ୈ Ұ

    $ 4 ݚ ڀ ։ ൃ ෦ ෰ ෦ ٛ ໌ IGDAɹSIG-Auido ษڧձ #2 13೥1݄20೔೔༵೔
  2. HDRΦʔσΟΦͱ͸ʁ DICEͷFROSTBITEΤϯδϯͰ࠾༻͞Ε͍ͯ ΔϘϦϡʔϜίϯτϩʔϧγεςϜ GDC2009ʮHow High Dynamic Audio Makes Battlefield:Bad Company

    GO BOOMʯͱ͍͏η ογϣϯͰ঺հ͞Ε͍ͯΔ http://www.slideshare.net/aclerwall/how-high-dynamic-range-audio- makes-battlefield-bad-company-go-boom-1292018 CryEngine3Ͱ΋αϙʔτ͞Ε͍ͯΔ 13೥1݄20೔೔༵೔
  3. ܭࢉํ๏ •͢΂ͯͷԻͷԻྔΛ߹ܭ͢Δ Lcurrent = 10 ⇥ log10( X n 10

    Ln 10 ) dB Ln:ͦΕͧΕͷα΢ϯυͷԻྔʢσγϕϧʣ Lcurrent:ݱࡏͷԻྔͷ߹ܭʢԻѹPaʣ 13೥1݄20೔೔༵೔
  4. Իѹͬͯʁ WikipediaͷʮԻѹϨϕϧʯͷઆ໌ΑΓ Իѹp (୯ҐʦPaʧ)ʹରͯ͠ɺԻѹϨϕϧLp (୯Ґ ʦdBʧ)͸࣍ͷΑ͏ʹఆٛ͞ΕΔɻ Lp = 10 ×

    log10(p2/p0 2) = 20 × log10(p/p0) ͜͜Ͱɺج४஋p0= 20 × 10-6 [Pa]Ͱ͋Γɺ͜Ε͸ ੈքڞ௨ͷఆٛͰ͋Δɻ 13೥1݄20೔೔༵೔
  5. ࣜͷઆ໌ Li = 20 ⇥ log10 Pi P0 Li =

    10 ⇥ log10 P2 i P2 0 10 Li 10 = P2 i P2 0 13೥1݄20೔೔༵೔
  6. ࣜͷઆ໌ Lall = 10 ⇥ log10 ✓ P2 1 P2

    0 + P2 2 P2 0 + . . . + P2 n P2 0 ◆ Lall = 10 ⇥ log10 ⇣ 10 L1 10 + 10 L2 10 + . . . + 10 L1 10 ⌘ Lall = 10 ⇥ log10 X n ⇣ 10 Ln 10 ⌘ ͢΂ͯͷԻͷԻѹΛ߹ܭͨ͠dBΛٻΊΔ 13೥1݄20೔೔༵೔
  7. ࣜͷઆ໌ ΢Οϯυ΢ͷ্୺(Lwintop)ΛҾ͍ͯɺԻѹʹ໭͢ Pn͸0.0ʙ1.0ʹͳΔ Ln Lwintop = 20 ⇥ log10 Pn

    Ln Lwintop 20 = log10 Pn 10 Ln Lwintop 20 = Pn 13೥1݄20೔೔༵೔
  8. ؆୯ͳܭࢉྫ 80dBͱ70dBͷSE͕ൃԻ͞Εͨ৔߹ 10 ⇥ log10 ⇣ 10 80 10 +

    10 70 10 ⌘ 10 ⇥ log10 10 8 + 10 7 10 ⇥ log10 10 7 (10 + 1) 10 ⇥ log10 10 7 + log10 11 70 + 10.4 = 80.4dB = Lwintop 13೥1݄20೔೔༵೔
  9. ؆୯ͳܭࢉྫ Afinal = pow 10(Lperceived Lwintop 20 ) 1070 80.4

    20 = 0.30 1080 80.4 20 = 0.95 wintop͔Β֤ԻͷԻྔ(0.0ʙ1.0)ΛٻΊΔ 13೥1݄20೔೔༵೔