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Old 11th January 2010, 21:53   #1  |  Link
Selur
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Audio up/downmix with SoX
Background: I wanted to add the possibility to up-/downmix the audio to sx264/Hybrid decoding with ffmpeg, piping the output to sox and then pipe it to ffmpeg or neroaacenc for encoding, problem is I found no documentation how to:
a. do a up/downmix with sox
b. do it in general, like what channels need to be mixed how

Anyone got infos on how to use SoX to do up- and downmixes and how up-/downmixes are done?

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Old 12th January 2010, 01:09   #2  |  Link
tebasuna51
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This Dolby ProLogic II downmix:
fl' = 0.3254xFL + 0.2301xC + 0.2818xSL + 0.1627xSR
fr' = 0.3254xFR + 0.2301xC - 0.1627xSL - 0.2818xSR

Can be implemented with SoX (and normalized) like:
sox 6w321.wav 2dpl.wav remix -m 1v0.3254,3v0.2301,5v0.2818,6v0.1627 2v0.3254,3v0.2301,5v-0.1627,6v-0.2818 norm

Of course you can use other coeficients for dpl I or simple stereo or add LFE to mix.

A correct upmix is more difficult to implement, in BeHappy there are some upmix functions using sox filter (thanks to NorthPole):
http://forum.doom9.org/showthread.ph...216#post787216
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Old 12th January 2010, 05:30   #3  |  Link
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Cool thanks !

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Old 12th January 2010, 12:26   #4  |  Link
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Just tried to convert a 5.1 ac3 audio file to mp3 using:
Quote:
ffmpeg -v 0 -threads 4 -i "AC3-5.1.ac3" -ac 6 -ar 48000 -acodec pcm_s16le -f wav - |
sox -t -s -b 16 -c 6 -r 48000 - -t wav - remix -m 1v0.3254,3v0.2301,5v0.2818,6v0.1627 2v0.3254,3v0.2301,5v-0.1627,6v-0.2818 norm |
ffmpeg -threads 4 -i - -ac 2 -y -ab 128000 -ac 2 -ar 48000 "test.mp3"
and it seems like it's working, only problem is: 'rear right'-channel is missing.
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Old 12th January 2010, 14:37   #5  |  Link
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What ffmpeg version are you using?
(I can't pipe to sox with my version)

Warning (maybe a typo):
... sox -t -s -b 16 -c 6 -r 48000 - ... must be
... sox -t wav -s -b 16 -c 6 -r 48000 -
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Old 12th January 2010, 14:45   #6  |  Link
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using here: SVN-r20817
used '-t wav' it just got lost on the way to the post
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Old 12th January 2010, 15:01   #7  |  Link
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Is there's some explanation somewhere how to get from http://en.wikipedia.org/wiki/Dolby_P...oding_matrices to:
Quote:
Dolby ProLogic II downmix:
fl' = 0.3254xFL + 0.2301xC + 0.2818xSL + 0.1627xSR
fr' = 0.3254xFR + 0.2301xC - 0.1627xSL - 0.2818xSR
?

Cu Selur

Ps.: damn, must have changed something with the calls, since I can't get the pipe working anymore
got it, the '-y' is needed
Code:
ffmpeg -y -i "AC3-5.1.ac3" -ac 6 -ar 48000 -acodec pcm_s16le -f wav - | sox -s -b 16 -c 6 -r 48000 -t raw - -t wav - remix -m 1v0.3254,3v0.2301,5v0.2818,6v0.1627 2v0.3254,3v0.2301,5v-0.1627,6v-0.2818 norm | ffmpeg -v -1 -threads 4 -y -i - -ab 128000 -ac 2 -ar 48000 "test.mp3"
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Last edited by Selur; 12th January 2010 at 16:49.
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Old 12th January 2010, 19:31   #8  |  Link
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Based on http://forum.doom9.org/showthread.ph...92#post1134992 and the infos posted in this thread I tried to convert the infos from the other post:

Code:
function Dmix5Dpl2(clip a)    # 5 Channels FL,LR,C,SL,SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3254, 0.2301)
  // 0.3254*FL+0.2301*C  0.3254*FR+0.2301*C
  bl  = GetChannel(a, 4)
  br  = GetChannel(a, 5)
  sl  = MixAudio(bl, br, 0.2818, 0.1627)
  // 0.2818*SL 0.1627*SR
  sr  = MixAudio(bl, br, -0.1627, -0.2818)
  // -0.1627*SL -0.2818*SR
  blr = MergeChannels(sl, sr)
  //0.2818*SL+0.1627*SR -0.1627*SL-0.2818*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
  //fl' = 0.3254*FL+0.2301*C+0.2818*SL+0.1627*SR
  //fr' = 0.3254*FR+0.2301*C-0.1627*SL-0.2818*SR
}
=> SoX remix part:
Code:
1v0.3254,3v0.2301,4v0.2818,5v0.1627 2v0.3254,3v0.2301,4v-0.1627,5v-0.2818
Code:
function Dmix6Dpl2Lfe(clip a) # 6 Channels FL,LR,C,SL,SR,SUB
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.2646, 0.1870)
  // 0.2646*FL+0.1870*C  0.2646FR+0.1870*C
  lfe = GetChannel(a, 4, 4)
  lrc = MixAudio(lrc, lfe, 1.0, 0.1870)
  // 0.2646*FL+0.1870*C+SL  0.2646*FR+0.1870*C+SL
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.2291, 0.1323)
  //  0.2291*SR   0.1323*SUB
  sr  = MixAudio(bl, br, -0.1323, -0.2291)
  //  -0.1323*SR -0.2291*SUB
  blr = MergeChannels(sl, sr)
  // 0.2291*SR+0.1323*SUB  -0.1323*SR-0.2291*SUB
  
  return MixAudio(lrc, blr, 1.0, 1.0)
  //fl' = 0.2646*FL+0.1870*C+SL+0.2291*SR+0.1323*SUB
  //fr' = 0.2646*FR+0.1870*C+SL-0.1323*SR-0.2291*SUB
}
=> SoX remix part:
Code:
1v0.2646,3v0.1870,4,5v0.2291,6v0.1323 1v0.2646,3v0.1870,4,5v-0.1323,6v-0.2291
Since I'm not sure if I got it right what the GetChannel/MixAudio/MergeChannel do it would be cool if someone could recheck this.
(Especially the part that Dmix6Dpl2Lfe->SoX contains in both channel more Infos from SL than from SR let's me suspect that I got something wrong.)

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Old 13th January 2010, 02:11   #9  |  Link
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Quote:
Originally Posted by Selur View Post
Is there's some explanation somewhere how to get from http://en.wikipedia.org/wiki/Dolby_P...oding_matrices to:
Is a very old story, the coeficients I put was assumed in BeSweet-Azid dpl II downmix after a study, in this forum, to obtain the best channel separation. I can confirm the results.
Quote:
Originally Posted by Selur View Post
...
[code]function Dmix6Dpl2Lfe(clip a) # 6 Channels FL,LR,C,SL,SR,SUB
...
lrc = MixAudio(lrc, lfe, 1.0, 0.1870)
// 0.2646*FL+0.1870*C+SL 0.2646*FR+0.1870*C+SL
...
Problems:
1) The correct channel order is FL,LR,C,SUB,SL,SR
2) You forget the 0.1870 when mix the SL (SUB)

Then must be:
fl' = 0.2646*FL +0.1870*C +0.1870*SUB +0.2291*SL +0.1323*SR
fr' = 0.2646*FR +0.1870*C +0.1870*SUB -0.1323*SL -0.2291*SR

And
1v0.2646,3v0.1870,4v0.1870,5v0.2291,6v0.1323 2v0.2646,3v0.1870,4v0.1870,5v-0.1323,6v-0.2291

Edit: Problems when use LFE (SUB) in the mix:
- Not recommended by Dolby because the mix can produce artifacts.
- The dpl decoder send the LFE content to Center channel (common part in FL-FR). The receiver must filter the low frequencies to subwoofer (the Center speaker can't be defined as "large")
Last edited by tebasuna51; 13th January 2010 at 02:27. Reason: LFE edit
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Old 13th January 2010, 09:05   #10  |  Link
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Thanks for the help!

Code:
function Dmix6Dpl2Lfe(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.2646, 0.1870)
  // 0.2646*FL+0.1870*C  0.2646FR+0.1870*C
  lfe = GetChannel(a, 4, 4)
  lrc = MixAudio(lrc, lfe, 1.0, 0.1870)
  // 0.2646*FL+0.1870*C+SUB*0.1870  0.2646*FR+0.1870*C+SUB*0.1870
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.2291, 0.1323)
  //  0.2291*SL   0.1323*SR
  sr  = MixAudio(bl, br, -0.1323, -0.2291)
  //  -0.1323*SL -0.2291*SR
  blr = MergeChannels(sl, sr)
  // 0.2291*SL+0.1323*SR  -0.1323*SL-0.2291*SR
  
  return MixAudio(lrc, blr, 1.0, 1.0)
  //fl' = 0.2646*FL+0.1870*C+SUB*0.1870+0.2291*SL+0.1323*SR
  //fr' = 0.2646*FR+0.1870*C+SUB*0.1870-0.1323*SL-0.2291*SR
}
SoX:
Code:
1v0.2646,3v0.1870,4v0.1870,5v0.2991,6v0.1323 2v0.2646,3v0.1870,4v0.1870,5v-0.1323,6v-0.2291
Code:
Problems when use LFE (SUB) in the mix
will add a ToolTip regarding this once I integrate the whole thing into sx264/Hybrid, thanks for the info.

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Last edited by Selur; 13th January 2010 at 09:20.
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Old 13th January 2010, 10:54   #11  |  Link
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For those interested, here's the full list with SoX remix calls:
Code:
function Dmix3Stereo(clip a)  # 3 Channels L,R,C or L,R,S
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  return MixAudio(flr, fcc, 0.5858, 0.4142)
  //0.5858*FL+0.4142*C 0.5858*FR+0.4142*C
}
SoX: 1v0.5858,3v0.4142 2v0.5858,3v0.4142

function Dmix3Dpl(clip a)     # 3 Channels only L,R,S
{
  flr = GetChannel(a, 1, 2)
  sl  = GetChannel(a, 3)
  sr  = Amplify(sl, -1.0)
  blr = MergeChannels(sl, sr)
  //S S*-1.0 
  return MixAudio(flr, blr, 0.5858, 0.4142)
  //FL*0.5858+S FR*0.4142+S*-1.0
}
SoX: 1v0.5858,3 2v0.4142,3v-1.0

function Dmix4qStereo(clip a) # 4 Channels Quadro L,R,SL,SR
{
  flr = GetChannel(a, 1, 2)
  blr = GetChannel(a, 3, 4)
  return MixAudio(flr, blr, 0.5, 0.5)
  //FL*0.5+SL*0.5 FR*0.5+SR*0.5
}
SoX: 1v0.5,3v0.5 2v0.5,3v0.5

function Dmix4qDpl(clip a)    # 4 Channels Quadro L,R,SL,SR
{
  flr = GetChannel(a, 1, 2)
  bl  = GetChannel(a, 3)
  br  = GetChannel(a, 4)
  sl  = MixAudio(bl, br, 0.2929, 0.2929)
  //0.2929*SR 0.2929*SL
  sr  = MixAudio(bl, br, -0.2929, -0.2929)
  //-0.2929*SR -0.2929*SL
  blr = MergeChannels(sl, sr)
  //0.2929*SR-0.2929*SR 0.2929*SL-0.2929*SL  <- Kann das Sinn machen?
  return MixAudio(flr, blr, 0.4142, 1.0)
  //0.4142*FL+0.2929*SR-0.2929*SR 0.4142*FR+0.2929*SL-0.2929*SL 
}
SoX: 1v0.4142,4v0.2929,4v-0.292 2v0.4142,3v0.2929,3v-0.292

function Dmix4qDpl2(clip a)   # 4 Channels Quadro L,R,SL,SR
{
  flr = GetChannel(a, 1, 2)
  bl  = GetChannel(a, 3)
  br  = GetChannel(a, 4)
  sl  = MixAudio(bl, br, 0.3714, 0.2144)
  //0.3714*SL 0.2144*SR
  sr  = MixAudio(bl, br, -0.2144, -0.3714)
  //-0.2144*SL -0.3714*SR
  blr = MergeChannels(sl, sr)
  //0.3714*SL-0.2144*SL 0.2144*SR-0.3714*SR
  return MixAudio(flr, blr, 0.4142, 1.0)
  //0.3712*FL+0.3714*SL-0.2144*SL FR+0.2144*SR-0.3714*SR
}
SoX: 1v0.4142,3v03714,3v-0.2144 2,3v0.2144,3v-0.3714

function Dmix4sStereo(clip a) # 4 Channels L,R,C,S
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.4142, 0.2929)
  //0.4142*FL+0.2929*C 0.4142*FR+0.2929*C
  blr = GetChannel(a, 4, 4)
  return MixAudio(lrc, blr, 1.0, 0.2929) //<- instead of MixAudio(flr, blr, 1.0, 0.2929)
  //0.4142*FL+0.2929*C+0.2929*SUB 0.4142*FR+0.2929*C+0.2929*SUB
}
SoX: 1v0.4142,3v0.2929,4v02929 2v0.4142,3v0.2929,4v02929

function Dmix4sDpl(clip a)    # 4 Channels L,R,C,S
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.4142, 0.2929)
  //0.4142*FL+0.2929*C 0.4142*FR+0.2929*C
  sl  = GetChannel(a, 4)
  sr  = Amplify(sl, -1.0)
  blr = MergeChannels(sl, sr)
  //SUB -1,0*SUB
  return MixAudio(flr, blr, 1.0, 0.2929)
  //0.4142*FL+0.2929*C+SUB 0.4142*FR+0.2929*C-1.0*SUB
}
SoX: 1v0.4142,3v0.2929,4 2v0.4142,3v0.2929,4v-1.0

function Dmix5Stereo(clip a)  # 5 Channels L,R,C,SL,SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3694, 0.2612)
  //0.3694*FL+0.2612*C 0.3694*FR+0.2612*C
  blr = GetChannel(a, 4, 5)
  return MixAudio(lrc, blr, 1.0, 0.3694)
  //0.3694*FL+0.2612*C+0.3694*SL 0.3694*FR+0.2612*C+0.3694*SR
}
SoX: 1v0.3694,3v0.2612,4v0.3694 2v0.3694,3v0.2612,5v0.3694

function Dmix5Dpl(clip a)     # 5 Channels L,R,C,SL,SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3205, 0.2265)
  //0.3205*FL+0.2265*C 0.3205*FR+0.2265*C
  bl  = GetChannel(a, 4)
  br  = GetChannel(a, 5)
  sl  = MixAudio(bl, br, 0.2265, 0.2265)
  //0.2265*SL 0.2265*SR
  sr  = MixAudio(bl, br, -0.2265, -0.2265)
  //-0.2265*SL -0.2265*SR
  blr = MergeChannels(sl, sr)
  //0.2265*SL-0.2265*SL 0.2265*SR-0.2265*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
//0.3205*FL+0.2265*C+0.2265*SL-0.2265*SL 0.3205*FR+0.2265*C+0.2265*SR-0.2265*SR
}
SoX: 1v0.3205,3v0.2265,4v0.2265,4v-0.2265 2v0.3205,3v0.2265,5v0.2265,5v-0.2265


function Dmix5Dpl2(clip a)    # 5 Channels FL,LR,C,SL,SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3254, 0.2301)
  // 0.3254*FL+0.2301*C  0.3254*FR+0.2301*C
  bl  = GetChannel(a, 4)
  br  = GetChannel(a, 5)
  sl  = MixAudio(bl, br, 0.2818, 0.1627)
  // 0.2818*SL 0.1627*SR
  sr  = MixAudio(bl, br, -0.1627, -0.2818)
  // -0.1627*SL -0.2818*SR
  blr = MergeChannels(sl, sr)
  //0.2818*SL+0.1627*SR -0.1627*SL-0.2818*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
  //fl' = 0.3254*FL+0.2301*C+0.2818*SL+0.1627*SR
  //fr' = 0.3254*FR+0.2301*C-0.1627*SL-0.2818*SR 
}
SoX: 1v0.3254,3v0.2301,4v0.2818,5v0.1627 2v0.3254,3v0.2301,4v-0.1627,5v-0.2818

function Dmix6Stereo(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3694, 0.2612)
  //0.3694*FL+0.2612*C 0.3694*FR+0.2612*C
  blr = GetChannel(a, 5, 6)
  return MixAudio(lrc, blr, 1.0, 0.3694)
 //0.3694*FL+0.2612*C+0.3694*SL 0.3694*FR+0.2612*C+0.3694*SR
}
SoX: 1v0.3694+3v0.2612+4v0.3694 2v0.3694+3v0.2612+5v0.3694

function Dmix6Dpl(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3205, 0.2265)
  //0.3205*FL+0.2265*C 0.3205*FR+0.2265*C
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.2265, 0.2265)
  //0.2265*SL 0.2265*SR
  sr  = MixAudio(bl, br, -0.2265, -0.2265)
  //-0.2265*SL -0.2265*SR
  blr = MergeChannels(sl, sr)
  //0.2265*SL-0.2265*SL 0.2265*SR-0.2265*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
  //0.3205*FL+0.2265*C+0.2265*SL-0.2265*SL 0.3205*FR+0.2265*C+0.2265*SR-0.2265*SR
}
SoX: 1v0.3205,3v0.2265+4v0.2265-4v-0.2265 2v0.3205,3v0.2265+5v0.2265-5v-0.2265


function Dmix6Dpl2(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3254, 0.2301)
  //0.3254*FL+0.2301*C 0.3254*FR+0.2301*C
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.2818, 0.1627)
  //0.2818*SL 1627*SR
  sr  = MixAudio(bl, br, -0.1627, -0.2818)
  //-0.1627*SL -0.2818*SR
  blr = MergeChannels(sl, sr)
  //0.2818*SL-0.1627*SL 1627*SR-0.2818*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
  //0.3254*FL+0.2301*C+0.2818*SL-0.1627*SL 0.3254*FR+0.2301*C+1627*SR-0.2818*SR
}
SoX: 1v0.3254,3v0.2301,5v0.2818,5v-0.1627 2v0.3254,3v0.2301,6v0.2818,6v-0.1627


function Dmix6StereoLfe(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.2929, 0.2071)
  //0.2929*FL+0.2071*C 0.2929*FR+0.2071*C
  lfe = GetChannel(a, 4, 4)
  lrc = MixAudio(lrc, lfe, 1.0, 0.2071)
  //0.2929*FL+0.2071*C+0.2071*SUB 0.2929*FR+0.2071*C+0.2071*SUB
  blr = GetChannel(a, 5, 6)
  return MixAudio(lrc, blr, 1.0, 0.2929)
  //0.2929*FL+0.2071*C+0.2071*SUB+0.2929*SL 0.2929*FR+0.2071*C+0.2071*SUB+0.2929*SR
}
SoX: 1v0.2929,3v0.2071,4v0.2071,5v0.2929 2v0.2929,3v0.2071,4v0.2071,6v0.2929

function Dmix6DplLfe(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.2613, 0.1847)
  //0.2613*FL+0.1847*C  0.2613*FR+0.1847*C
  lfe = GetChannel(a, 4, 4)
  lrc = MixAudio(lrc, lfe, 1.0, 0.1847)
  //0.2613*FL+0.1847*C+0.1847*SUB  0.2613*FR+0.1847*C+0.1847*SUB
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.1847, 0.1847)
  //0.1847*SL 0.1847*SR
  sr  = MixAudio(bl, br, -0.1847, -0.1847)
  //-0.1847*SL -0.1847*SR
  blr = MergeChannels(sl, sr)
  //0.1847*SL-0.1847*SL 0.1847*SR-0.1847*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
  //0.2613*FL+0.1847*C+0.1847*SUB+0.1847*SL-0.1847*SL 0.2613*FR+0.1847*C+0.1847*SUB+0.1847*SR-0.1847*SR
}
SoX: 1v0.2613,3v0.1847,4v0.1847,5v0.1847,5v-0.1847 2v0.2613,3v0.1847,4v0.1847,6v0.1847,6v-0.1847

function Dmix6Dpl2Lfe(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.2646, 0.1870)
  // 0.2646*FL+0.1870*C  0.2646FR+0.1870*C
  lfe = GetChannel(a, 4, 4)
  lrc = MixAudio(lrc, lfe, 1.0, 0.1870)
  // 0.2646*FL+0.1870*C+SUB*0.1870  0.2646*FR+0.1870*C+SUB*0.1870
  bl  = GetChannel(a, 5)
  br  = GetChannel(a, 6)
  sl  = MixAudio(bl, br, 0.2291, 0.1323)
  //  0.2291*SL   0.1323*SR
  sr  = MixAudio(bl, br, -0.1323, -0.2291)
  //  -0.1323*SL -0.2291*SR
  blr = MergeChannels(sl, sr)
  // 0.2291*SL+0.1323*SR  -0.1323*SL-0.2291*SR
  
  return MixAudio(lrc, blr, 1.0, 1.0)
  //fl' = 0.2646*FL+0.1870*C+SUB*0.1870+0.2291*SL+0.1323*SR
  //fr' = 0.2646*FR+0.1870*C+SUB*0.1870-0.1323*SL-0.2291*SR
}
SoX: 1v0.2646,3v0.1870,4v0.1870,5v0.2991,6v0.1323 2v0.2646,3v0.1870,4v0.1870,5v-0.1323,6v-0.2291
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Old 13th January 2010, 18:27   #12  |  Link
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Quote:
Originally Posted by tebasuna51 View Post
Of course you can use other coeficients for dpl I or simple stereo or add LFE to mix.
So what coefficients are you suggesting for a simple stereo downmix ? (not DPL I or II)
I mean playing a 5.1 or 7.1 audio track on a computer with stereo speakers only.
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Old 14th January 2010, 00:50   #13  |  Link
tebasuna51
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Quote:
Originally Posted by Brazil2 View Post
So what coefficients are you suggesting for a simple stereo downmix ? (not DPL I or II)
I mean playing a 5.1 or 7.1 audio track on a computer with stereo speakers only.
You have the answer in the precedent post:

Code:
function Dmix6Stereo(clip a) # 6 Channels FL, FR, C, LFE, SL, SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3694, 0.2612)
  //0.3694*FL+0.2612*C 0.3694*FR+0.2612*C
  blr = GetChannel(a, 5, 6)
  return MixAudio(lrc, blr, 1.0, 0.3694)
 //0.3694*FL+0.2612*C+0.3694*SL 0.3694*FR+0.2612*C+0.3694*SR
}
SoX: 1v0.3694+3v0.2612+4v0.3694 2v0.3694+3v0.2612+5v0.3694
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Old 14th January 2010, 10:14   #14  |  Link
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I'm a bit confused about all the dpl downmixes , e.g.

Code:
function Dmix5Dpl(clip a)     # 5 Channels L,R,C,SL,SR
{
  flr = GetChannel(a, 1, 2)
  fcc = GetChannel(a, 3, 3)
  lrc = MixAudio(flr, fcc, 0.3205, 0.2265)
  //0.3205*FL+0.2265*C 0.3205*FR+0.2265*C
  bl  = GetChannel(a, 4)
  br  = GetChannel(a, 5)
  sl  = MixAudio(bl, br, 0.2265, 0.2265)
  //0.2265*SL 0.2265*SR
  sr  = MixAudio(bl, br, -0.2265, -0.2265)
  //-0.2265*SL -0.2265*SR
  blr = MergeChannels(sl, sr)
  //0.2265*SL-0.2265*SL 0.2265*SR-0.2265*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
//0.3205*FL+0.2265*C+0.2265*SL-0.2265*SL 0.3205*FR+0.2265*C+0.2265*SR-0.2265*SR
}
SoX: 1v0.3205,3v0.2265,4v0.2265,4v-0.2265 2v0.3205,3v0.2265,5v0.2265,5v-0.2265
wouldn't something like: 4v0.2265,4v-0.2265 result in no change?
I suspect I should have used another SoX open to represent the negative values or I just don't get what the mean.

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Old 14th January 2010, 11:37   #15  |  Link
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Quote:
Originally Posted by Selur View Post
I'm a bit confused about all the dpl downmixes , e.g.

Code:
function Dmix5Dpl(clip a)     # 5 Channels L,R,C,SL,SR
...
  sl  = MixAudio(bl, br, 0.2265, 0.2265)
  //0.2265*SL 0.2265*SR
  sr  = MixAudio(bl, br, -0.2265, -0.2265)
  //-0.2265*SL -0.2265*SR
  blr = MergeChannels(sl, sr)
  //0.2265*SL-0.2265*SL 0.2265*SR-0.2265*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
//0.3205*FL+0.2265*C+0.2265*SL-0.2265*SL 0.3205*FR+0.2265*C+0.2265*SR-0.2265*SR
}
SoX: 1v0.3205,3v0.2265,4v0.2265,4v-0.2265 2v0.3205,3v0.2265,5v0.2265,5v-0.2265
wouldn't something like: 4v0.2265,4v-0.2265 result in no change?
Sorry, I don't verify all functions, mergechannels sl, sr is:
Code:
  blr = MergeChannels(sl, sr)
  //0.2265*SL+0.2265*SR -0.2265*SL-0.2265*SR
  return MixAudio(lrc, blr, 1.0, 1.0)
//0.3205*FL+0.2265*C+0.2265*SL+0.2265*SR 0.3205*FR+0.2265*C-0.2265*SL-0.2265*SR
}
SoX: 1v0.3205,3v0.2265,4v0.2265,5v0.2265 2v0.3205,3v0.2265,4v-0.2265,5v-0.2265
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Old 14th January 2010, 11:40   #16  |  Link
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okay, that solves my confusion
Thanks again !

all the functions are ment to be symetric:
Quote:
sl = MixAudio(bl, br, 0.2291, 0.1323)
// 0.2291*SL 0.1323*SR
sr = MixAudio(bl, br, -0.1323, -0.2291)
// -0.1323*SL -0.2291*SR
blr = MergeChannels(sl, sr)
// 0.2291*SL+0.1323*SR -0.1323*SL-0.2291*SR
should then be:
Quote:
sl = MixAudio(bl, br, 0.2291, 0.2291)
// 0.2291*SL 0.2291*SR
sr = MixAudio(bl, br, -0.1323, -0.1323
// -0.1323*SL -0.1323*SR
blr = MergeChannels(sl, sr)
// 0.2291*SL-0.1323*SR 0.2291*SR-0.1323*SL
right ?
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Last edited by Selur; 14th January 2010 at 11:52.
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Old 14th January 2010, 13:06   #17  |  Link
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Quote:
Originally Posted by Selur View Post
all the functions are ment to be symetric:
Code:
sl = MixAudio(bl, br, 0.2291, 0.1323)
// 0.2291*SL 0.1323*SR
sr = MixAudio(bl, br, -0.1323, -0.2291)
// -0.1323*SL -0.2291*SR
blr = MergeChannels(sl, sr)
// 0.2291*SL+0.1323*SR -0.1323*SL-0.2291*SR
is a correct Dolby ProLogic II mix (recover 5.0)
Quote:
should then be:
Code:
sl = MixAudio(bl, br, 0.2291, 0.2291)
// 0.2291*SL+0.2291*SR (1 channel)
sr = MixAudio(bl, br, -0.1323, -0.1323)
// -0.1323*SL-0.1323*SR (1 channel)
blr = MergeChannels(sl, sr)
// 0.2291*SL-0.1323*SR, 0.2291*SR-0.1323*SL (2 channels)
right ?
wrong, the result is:

// 0.2291*SL+0.2291*SR, -0.1323*SR-0.1323*SL
and this isn't a correct mix, isn't stereo, isn't dpl, isn't dpl II

Remember:
MixAudio take 2 audios (with 1 or more channels each one) and return only a mixed one audio.
MergeChannels take 2 (or more) channels and return a multichannel audio without mix.
Last edited by tebasuna51; 14th January 2010 at 13:19.
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Old 14th January 2010, 13:08   #18  |  Link
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DOH, I misunderstood the MixAudio

Quote:
MixAudio take 2 (or more) channels and return only a mixed one.
this would mean for 3toStereo
Code:
function Dmix3Stereo(clip a)  # 3 Channels L,R,C or L,R,S
{
  flr = GetChannel(a, 1, 2)
  //FL FR (2 channel)
  fcc = GetChannel(a, 3, 3)
  //C C (2 channel)
  return MixAudio(flr, fcc, 0.5858, 0.4142)
    //0.5858*FL+0.4142*C 0.5858*FR+0.4142*C
}
-> MixAudio returns a two channel stream since it was fed with two 2 channel inputs
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Last edited by Selur; 14th January 2010 at 13:23.
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Old 14th January 2010, 14:56   #19  |  Link
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So is this right:
Code:
function Dmix5Dpl(clip a)     # 5 Channels L,R,C,SL,SR
{
  flr = GetChannel(a, 1, 2)			        //FL FR (2 channel)
  fcc = GetChannel(a, 3, 3)  				//C C(2 channel)
  lrc = MixAudio(flr, fcc, 0.3205, 0.2265)          //0.3205*FL+0.2265*C  0.3205*FR+0.2265*C
  bl  = GetChannel(a, 4)				       //SL (1 channel)
  br  = GetChannel(a, 5)			       //SR (1 channel)
  sl  = MixAudio(bl, br, 0.2265, 0.2265)           //0.2265*SL+0.2265*SR (1 channel)
  sr  = MixAudio(bl, br, -0.2265, -0.2265)        //-0.2265*SL-0.2265*SR (1 channel)
  blr = MergeChannels(sl, sr)                        //0.2265*SL+0.2265*SR   -0.2265*SL-0.2265*SR (2 channel)
  return MixAudio(lrc, blr, 1.0, 1.0)                //0.3205*FL+0.2265*C+0.2265*SL+0.2265*SR     0.3205*FR+0.2265*C-0.2265*SL-0.2265*SR (2 channel)
}
... still uncertain about the MergeChannels function
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Last edited by Selur; 14th January 2010 at 15:02.
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Old 22nd March 2010, 18:22   #20  |  Link
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Finally found the time and motivation to try to convert one of NorthPole's BeHappy UpMix functions to sox.
Function to be converted:
Code:
<Option>
          <Name>Audio with a mix of sounds (ie. Action, Adventure)</Name>
          <Value>
	# Profile to use with audio sources that have a wider range of sound content. 20ms delay and -3db attenuation on surround
	# Note: General purpose profile
	front_{2} = stereo_{2}.soxfilter("filter 20-20000")
	back_{2} = stereo_{2}.soxfilter("filter 100-7000")
	fl_{2} = mixaudio(front_{2}.GetLeftChannel(),front_{2}.GetRightChannel(),0.668,-0.668)
	fr_{2} = mixaudio(front_{2}.GetRightChannel(),front_{2}.GetLeftChannel(),0.668,-0.668)
	cc_{2} = mixaudio(mixaudio(front_{2}.GetLeftChannel(),fl_{2},1,-1),mixaudio(front_{2}.GetRightChannel(),fr_{2},1,-1),0.398,0.398)
	lfe_{2} = ConvertToMono(stereo_{2}).SoxFilter("lowpass 120","vol -0.447")
	sl_{2} = mixaudio(back_{2}.GetLeftChannel(),back_{2}.GetRightChannel(),0.473,-0.473)
	sr_{2} = mixaudio(back_{2}.GetRightChannel(),back_{2}.GetLeftChannel(),0.473,-0.473)
	sl_{2} = DelayAudio(sl_{2},0.02)
	sr_{2} = DelayAudio(sr_{2},0.02)
          </Value>
        </Option>
        <Option>
Me trying to convert it:
Code:
#input to wav
mplayer -ao pcm input.mp3 -ao pcm:file="dump.wav"

#resample to 48kHz and lower volume to avaid clipping
sox -S -V -c 2 dump.wav -r 48k stereoInput.wav gain -h

#front = stereo.soxfilter("filter 20-20000")
sox -S -V -c 2 stereoInput.wav front.wav sinc 20-20000
sox -S -V -c 2 front.wav -c 1 frontL.wav mixer -l
sox -S -V -c 2 front.wav -c 1 frontR.wav mixer -r

#fl = mixaudio(front.GetLeftChannel(),front.GetRightChannel(),0.794,-0.794)
sox -S -V -c 2 front.wav front_left.wav remix -m 1v0.794,2v-0.794

#fr = mixaudio(front.GetRightChannel(),front.GetLeftChannel(),0.794,-0.794)
sox -S -V -c 2 front.wav front_right.wav remix -m 2v0.794,1v-0.794

#rear = stereo.soxfilter("filter 100-7000")
sox -S -V -c 2 stereoInput.wav rear.wav sinc 100-7000

#sl = mixaudio(rear.GetLeftChannel(),rear.GetRightChannel(),0.562,-0.562)
#sl = DelayAudio(sl,0.02)
sox -S -V -c 2 rear.wav rear_left.wav remix -m 1v0.562,2v-0.562 delay 0.02

#sr = mixaudio(rear.GetRightChannel(),rear.GetLeftChannel(),0.562,-0.562)
#sr = DelayAudio(sr,0.02)
sox -S -V -c 2 rear.wav rear_right.wav remix -m 1v0.562,2v-0.562 delay 0.02

#cc = mixaudio(mixaudio(front.GetLeftChannel(),fl,1,-1),mixaudio(front.GetRightChannel(),fr,1,-1),0.224,0.224)
#   = mixaudio(cc_l, cc_r, 0.224,0.224)
#cc_l(1) = mixaudio(front.GetLeftChannel(),fl,1,-1)
#cc_r(1) = mixaudio(front.GetRightChannel(),fr,1,-1)
sox -S -V -M frontL.wav front_left.wav centerL.wav remix -m 1v0.224,2v-0.224
sox -S -V -M frontR.wav front_right.wav centerR.wav remix -m 1v0.224,2v-0.224
sox -S -V -m centerL.wav centerR.wav center.wav

#lfe = ConvertToMono(stereo).SoxFilter("lowpass 120","vol -0.596")
sox -S -V -v -0.596 stereoInput.wav -c 1 lfe.wav lowpass 120 remix -	

#merge channels
sox -S -V -M front_left.wav front_right.wav rear_left.wav rear_right.wav center.wav lfe.wav multichannel.wav

#normalize + making sure it's 16bit
sox -S -V -G multichannel.wav -b 16 normalize.wav

#convert
neroAacEnc -if normalize.wav -br 196k -ignorelength -of "test.mp4"
Hope someone understands my go at it, can verify it and help if it's wrong. (I'm pretty sure this should be possible with less intermediate files,... )

Cu Selur
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Last edited by Selur; 24th March 2010 at 09:44.
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