* compression @ 2017-12-06 22:39 Glenn English 2017-12-06 23:29 ` compression Jeremy Nicoll - ml sox users 0 siblings, 1 reply; 3+ messages in thread From: Glenn English @ 2017-12-06 22:39 UTC (permalink / raw) To: sox-users I want to compress some audio -- the quiet parts are too quiet for a road trip. AFAICT, there are 2 compression effects: compand and contast. Compand doesn't seem to have a ratio param. Contrast isn't explained in much detail, and it doesn't have much at all in the way of params anyway. Can anyone explain to me how to get sox to do a simple compression with an adjustable compression ratio? -- Glenn English ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Sox-users mailing list Sox-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-users ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: compression 2017-12-06 22:39 compression Glenn English @ 2017-12-06 23:29 ` Jeremy Nicoll - ml sox users 2017-12-06 23:33 ` compression Glenn English 0 siblings, 1 reply; 3+ messages in thread From: Jeremy Nicoll - ml sox users @ 2017-12-06 23:29 UTC (permalink / raw) To: sox-users On 2017-12-06 22:39, Glenn English wrote: > I want to compress some audio -- the quiet parts are too quiet for a > road trip. > > AFAICT, there are 2 compression effects: compand and contast. > > Compand doesn't seem to have a ratio param. Contrast isn't explained > in much detail, and it doesn't have much at all in the way of params > anyway. > > Can anyone explain to me how to get sox to do a simple compression > with an adjustable compression ratio? The manual has a specific example of the use of compand, for making music suitable for listening to in a car. I'd have thought you could start by trying the example, then tweaking the settings to suit your music. In the description of the parameters in that example, it says "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". I presume that the 3:1 ratio and those quoted 60dB & 20dB values correspond to the "-60" and "-20" parameters in the example. I guess you might need to use the stat/stats effects to discover the dynamic range of a piece of music first, to work out eg the values of the overall gain, if any, to be applied. As is often the case in sox documentation, it requires a very careful look at the required and optional parms for the effect, with the example, to see which parts have been provided. I found for example when I first looked at this that I (wrongly) thought that where the description shows that attack1,decay1 might be followed by attack2,decay2 and on the line below shows that in-dB1,out-dB1 might be followed by in-dB2,out-dB2 that those two sets of optional second instances of parameters were connected ie if you had multiple sets of attach,delay, you needed multiple sets of in&out dBs. They're not. Moreover, in the example the 'transfer function' is given as: 6:−70,−60,−20 and it took me a while to realise that that corresponds to: [soft-knee-dB:]in-dB1[,out-dB1]{,in-dB2,out-dB2} with out-dB1 (as it says it can be) omitted. I think the example would have been easier to understand if it was coded as: 6:−70,-70,−60,−20 (which is what I think it actually means). I may well be wrong! -- Jeremy Nicoll - my opinions are my own ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Sox-users mailing list Sox-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-users ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: compression 2017-12-06 23:29 ` compression Jeremy Nicoll - ml sox users @ 2017-12-06 23:33 ` Glenn English 0 siblings, 0 replies; 3+ messages in thread From: Glenn English @ 2017-12-06 23:33 UTC (permalink / raw) To: sox-users On Wed, Dec 6, 2017 at 11:29 PM, Jeremy Nicoll - ml sox users <jn.ml.sxu.88@wingsandbeaks.org.uk> wrote: > The manual has a specific example of the use of compand, for making music > suitable for listening to in a car. I'd have thought you could start by > trying the example, then tweaking the settings to suit your music. > > In the description of the parameters in that example, it says "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". I presume that the 3:1 ratio and those quoted 60dB & 20dB values > correspond to the "-60" and "-20" parameters in the example. Sorry and thanks. I missed that... -- Glenn English ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Sox-users mailing list Sox-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-users ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-12-06 23:34 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2017-12-06 22:39 compression Glenn English 2017-12-06 23:29 ` compression Jeremy Nicoll - ml sox users 2017-12-06 23:33 ` compression Glenn English
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