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  1. #1
    Avatar von xorg1990
    xorg1990 ist offline König
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    19-12-2013
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    SoX Filter chain?

    Hi, habe mal ein frage zu SoX.

    Auf dieser Seite ist ein SOX beispiel https://github.com/drmpeg/gr-cessb
    sox ssbaudio.wav -b 16 ssbaudioprocessed.wav compand 0.0,0.01 0.25:-20,-20,0,-20 -0.1 -40 .0005 gain -n -3.0102999566

    Diesen compand befehl hatte ich gerne auf den sound input angewandt.

    Wenn aber ich schreibe:
    rec -r 48000 -b 16 -c1 -p | sox -p -t alsa default | sox compand 0.0,0.01 0.25:-20,-20,0,-20 -0.1 -40 .0005 gain -n -3.0102999566

    Dann funktioniert der compand befehl nicht.

    Weiß da einer mehr?

  2. #2
    Avatar von kkapsner
    kkapsner ist offline Super Moderator
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    AW: SoX Filter chain?

    Du musst "-" als Dateiname angeben, da sox sonst nicht weiß, dass es von stdin lesen/nach sdtout schreiben soll: SoX

  3. #3
    Avatar von xorg1990
    xorg1990 ist offline König
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    AW: SoX Filter chain?

    Danke für die schnelle Antwort, aber wo genau muss das "-" hin kannst du das mal bitte einstanzen.


    Halt stop... anders. in ffmpeg gibt es auch noch mal compand (Dynamic compressor): https://ffmpeg.org/ffmpeg-filters.html#compand
    kannst Du mir den SoX compand nach ffmpeg übersetzen, komme mit dem Syntax überhaut nicht klar.

    SoX: SoX
    compand attack1,decay1{,attack2,decay2}

    [soft-knee-dB:]in-dB1[,out-dB1]{,in-dB2,out-dB2}
    [gain [initial-volume-dB [delay]]]

    Compand (compress or expand) the dynamic range of the audio.

    The attack and decay parameters (in seconds) determine the time over which the instantaneous level of the input signal is averaged to determine its volume; attacks refer to increases in volume and decays refer to decreases. For most situations, the attack time (response to the music getting louder) should be shorter than the decay time because the human ear is more sensitive to sudden loud music than sudden soft music. Where more than one pair of attack/decay parameters are specified, each input channel is companded separately and the number of pairs must agree with the number of input channels. Typical values are 0.3,0.8 seconds.

    The second parameter is a list of points on the compander’s transfer function specified in dB relative to the maximum possible signal amplitude. The input values must be in a strictly increasing order but the transfer function does not have to be monotonically rising. If omitted, the value of out-dB1 defaults to the same value as in-dB1; levels below in-dB1 are not companded (but may have gain applied to them). The point 0,0 is assumed but may be overridden (by 0,out-dBn). If the list is preceded by a soft-knee-dB value, then the points at where adjacent line segments on the transfer function meet will be rounded by the amount given. Typical values for the transfer function are 6:−70,−60,−20.

    The third (optional) parameter is an additional gain in dB to be applied at all points on the transfer function and allows easy adjustment of the overall gain.

    The fourth (optional) parameter is an initial level to be assumed for each channel when companding starts. This permits the user to supply a nominal level initially, so that, for example, a very large gain is not applied to initial signal levels before the companding action has begun to operate: it is quite probable that in such an event, the output would be severely clipped while the compander gain properly adjusts itself. A typical value (for audio which is initially quiet) is −90 dB.

    The fifth (optional) parameter is a delay in seconds. The input signal is analysed immediately to control the compander, but it is delayed before being fed to the volume adjuster. Specifying a delay approximately equal to the attack/decay times allows the compander to effectively operate in a ‘predictive’ rather than a reactive mode. A typical value is 0.2 seconds.

    Image soxpng/grohtml-25597.png

    The following example might be used to make a piece of music with both quiet and loud passages suitable for listening to in a noisy environment such as a moving vehicle:

    sox asz.wav asz-car.wav compand 0.3,1 6:−70,−60,−20 −5 −90 0.2
    The transfer function (‘6:−70,...’) says that very soft sounds (below −70dB) will remain unchanged. This will stop the compander from boosting the volume on ‘silent’ passages such as between movements. However, sounds in the range −60dB to 0dB (maximum volume) will be boosted so that the 60dB dynamic range of the original music will be compressed 3-to-1 into a 20dB range, which is wide enough to enjoy the music but narrow enough to get around the road noise. The ‘6:’ selects 6dB soft-knee companding. The −5 (dB) output gain is needed to avoid clipping (the number is inexact, and was derived by experimentation). The −90 (dB) for the initial volume will work fine for a clip that starts with near silence, and the delay of 0.2 (seconds) has the effect of causing the compander to react a bit more quickly to sudden volume changes.

    In the next example, compand is being used as a noise-gate for when the noise is at a lower level than the signal:

    play infile compand .1,.2 −inf,−50.1,−inf,−50,−50 0 −90 .1
    Here is another noise-gate, this time for when the noise is at a higher level than the signal (making it, in some ways, similar to squelch):

    play infile compand .1,.1 −45.1,−45,−inf,0,−inf 45 −90 .1
    Habe jetzt compand=attacks=0.0:decays=0.01:points=0.25/-20|0|-20/-0.1:soft-knee=?:gain?:volume=-40:delay=0.0005
    funktioniert aber nicht

    - - - Aktualisiert - - -

    Nachtrag: compand ist ein "Compander" kein Compressor:
    https://de.wikipedia.org/wiki/Kompandierung

  4. #4
    Avatar von xorg1990
    xorg1990 ist offline König
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    AW: SoX Filter chain?

    Habe die Tage noch mal rum probiert, bekomme es aber nicht zu laufen, an dem "-" lag es nicht und bei den ffmpeg compand kommt immer diese Fehlermeldung:
    [Parsed_compand_0 @ 0x558ad4feed40] Invalid and/or missing input/output value.
    [Parsed_compand_0 @ 0x558ad4feed40] Failed to configure output pad on Parsed_compand_0
    Error reinitializing filters!
    Failed to inject frame into filter network: Invalid argument
    Error while processing the decoded data for stream #0:0
    Conversion failed!

    Eingegeben habe ich ffmpeg -i ssbaudio.wav -af "compand=attacks=0.0:decays=0.01:points=0.25/-20|0|-20:gain=-0.1:volume=-40:delay=0.0005" -acodec pcm_s16le -ar 48000 -ac 1 out.wav

    Stattdessen SOX: sox compand 0.0,0.01 0.25:-20,-20,0,-20 -0.1 -40 .0005
    Irgendwas ist falsch, nur was?

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