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Old 21st April 2014, 22:38   #161  |  Link
Richard1485
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Thanks. I downloaded Haali from videohelp.com, so I think I'll just ignore the message.
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Old 4th July 2019, 20:58   #162  |  Link
orion44
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Quote:
Originally Posted by tebasuna51 View Post
Downmix -down2 and simple stereo for all standard channel configuration.

If exist the parameter -mixlfe add:
FL' = ... + 0.7071 x LFE
FR' = ... + 0.7071 x LFE

Code:
2.1
    Stereo
        FL' = FL
        FR' = FR

2/1 or 2/1.1
    Stereo
        FL' = FL + 0.7071 x BC
        FR' = FR + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x BC
        FR' = FR - 0.7071 x BC

2/2 or 2/2.1
    Stereo
        FL' = FL + BL
        FR' = FR + BR
    Dpl
        FL' = FL + 0.8660 x BL + 0.5000 x BR
        FR' = FR - 0.5000 x BL - 0.8660 x BR

3/0 or 3/0.1
    Stereo
        FL' = FL + 0.7071 x FC
        FR' = FR + 0.7071 x FC

3/1 or 3/1.1
    Stereo
        FL' = FL + 0.7071 x FC + 0.7071 x BC
        FR' = FR + 0.7071 x FC + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x FC + 0.7071 x BC
        FR' = FR + 0.7071 x FC - 0.7071 x BC

3/2 or 3/2.1
    Stereo
        FL' = FL + 0.7071 x FC + BL
        FR' = FR + 0.7071 x FC + BR
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x BL + 0.5000 x BR
        FR' = FR + 0.7071 x FC - 0.5000 x BL - 0.8660 x BR

3/2/1 or 3/2/1.1
    Stereo
        FL' = FL + 0.7071 x FC + BL + 0.7071 x BC
        FR' = FR + 0.7071 x FC + BR + 0.7071 x BC
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x BL + 0.5000 x BR + 0.7071 x BC
        FR' = FR + 0.7071 x FC - 0.5000 x BL - 0.8660 x BR - 0.7071 x BC

3/2/2 or 3/2/2.1
    Stereo
        FL' = FL + 0.7071 x FC + BL + SL
        FR' = FR + 0.7071 x FC + BR + SR
    Dpl
        FL' = FL + 0.7071 x FC + 0.8660 x (BL + SL) + 0.5000 x (BR + SR)
        FR' = FR + 0.7071 x FC - 0.5000 x (BL + SL) - 0.8660 x (BR + SR)
Could you please provide a formula for the option -down6?
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Old 5th July 2019, 00:47   #163  |  Link
tebasuna51
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Quote:
Originally Posted by orion44 View Post
Could you please provide a formula for the option -down6?
I supose from 6.1 or 7.1 to 5.1

The first four channels (FL,FR,FC,LFE) must remain the same to avoid changes in volume, I can't recommend a Normalize like after a down2.

Only the Side and Back channels must be used to obtain 2 Surround channels.

6.1 to 5.1

SL' = BL + 0.7071 x BC
SR' = BR + 0.7071 x BC

Normalized to avoid clip:

SL' = 0.5879 x BL + 0.4142 x BC
SR' = 0.5879 x BR + 0.4142 x BC

Or best option with BeHappy or MeGUI and AviSynth plugin AudioLimiter:

SL' = MixAudio(BL, BC, 1, 0.7071).SoftClipperFromAudX(0.0)
SR' = MixAudio(BR, BC, 1, 0.7071).SoftClipperFromAudX(0.0)

7.1 to 5.1

SL' = BL + SL
SR' = BR + SR

Normalized to avoid clip:

SL' = 0.5 x BL + 0.5 x SL
SR' = 0.5 x BR + 0.5 x SR

Or best option with BeHappy or MeGUI and AviSynth:

SL' = MixAudio(BL, SL, 1, 1).SoftClipperFromAudX(0.0)
SR' = MixAudio(BR, SR, 1, 1).SoftClipperFromAudX(0.0)

With the AudioLimiter plugin we obtain the same volume, most the time, with 2 surround speakers in 5.1 than 4 speakers in 7.1.
Only moments with high volume we can't preserve the volume balance between front and surround channels.
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Old 5th July 2019, 16:39   #164  |  Link
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Quote:
Originally Posted by tebasuna51 View Post
7.1 to 5.1

Normalized to avoid clip:

SL' = 0.5 x BL + 0.5 x SL
SR' = 0.5 x BR + 0.5 x SR
How much volume decrease is this in decibels?

Is there a way to convert these formulas to get values in decibels, for each channel?
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Old 6th July 2019, 03:15   #165  |  Link
tebasuna51
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The coeficients (X) are relation between voltage the power dB's change are:

dB = 20 * log (X)

20 * log (0.5) = -6.02 dB
20 * log (0.7071) = -3.01 dB
...
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Old 6th July 2019, 21:44   #166  |  Link
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When converting a 5.1 or 7.1 audio to stereo WAV, is there a way to equalize loudness during conversion,
so that the normal parts remain unchanged, and loud parts get decreased in volume?

Can this be done in ffmpeg or avisynth? Some filter, maybe?
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Old 6th July 2019, 23:25   #167  |  Link
tebasuna51
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This is the purpose of SoftClipperFromAudX().
I think is safe to use it to mix surround channels first (7.1 -> 5.1), maybe can be used also to mix front with surround (5.1 -> 3.1) and after to 2.0:

FL' = FL + 0.7071 x FC
FR' = FR + 0.7071 x FC

and Normalize.
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