Paul, you do have some excellent filter additions! On Wed, Nov 25, 2015 at 16:32:13 +0100, Paul B Mahol wrote: > +@section acompressor
Very good description, few remarks only: > +A compressor is mainly used to reduce the dynamic of a signal. > +Especially modern music is mostly compressed at a high ratio to > +improve the overall loudness. It's done to get the highest attention > +of a listener, "fatten" the sound and bring more "power" to the track. > +If a signal is compressed too much it may sound dull or "dead" > +afterwards or it may start to "pump" (which could be a powerful effect > +but can also destroy a track completely). > +The right compression is the key to reach a professional sound and is > +the high art of mixing and mastering. Because of it's complex settings it's -> its > +Compression is done by detecting the volume above a chosen level > +@code{threshold} and divide it by the factor set with @code{ratio}. divide -> dividing (stick to the infinitive, as for "detecting") > +So if you set the threshold to -12dB and your signal reaches -6dB a ratio > +of 2:1 will result in a signal at -9dB. Because an exact manipulation of > +the signal would cause distrotion of the waveform the reduction can be distrotion -> distortion > +levelled over the time. This is done by setting "Attack" and "Release". > +@code{attack} determines how long the signal has to rise above the threshold > +before any reduction will occur and @code{release} sets the time the signal > +has to fall below the threshold to reduce the reduction again. Shorter > signals > +than the chosen attack time will be left untouched. > +The overall reduction of the signal can be made up afterwards with the > +@code{makeup} setting. So compressing the peaks of a signal about 6dB and > +rising the makeup to this level results in a signal two times louder than the rising -> raising "two times louder" (which could be read as "three times as loud") or "twice as loud"? > +source. To gain a softer entry in the compression the @code{knee} flattens > the > +hard edge at the threshold in the range of the chosen decibels. > + > +The filter accepts the following options: > + > +@table @option > +@item threshold > +If a signal of second stream raises above this level it will affect the gain > +reduction of first stream. raises -> rises ("to rise" is active, "to be raised" is passive) of ... stream -> of the ... stream > +By default is 0.125. Range is between 0.00097563 and 1. "By default is" -> "By default it is" or "The default is" or "Default is" > +@item ratio > +Set a ratio about which the signal is reduced. 1:2 means that if the level "about which" -> "by which" > +raised 4dB above the threshold, it will be only 2dB above after the > reduction. > +Default is 2. Range is between 1 and 20. raised -> rose (active, again ;-)) > +@item attack > +Amount of milliseconds the signal has to rise above the threshold before gain > +reduction starts. Default is 20. Range is between 0.01 and 2000. > + > +@item release > +Amount of milliseconds the signal has to fall below the threshold before > +reduction is decreased again. Default is 250. Range is between 0.01 and 9000. > + > +@item makeup > +Set the amount by how much signal will be amplified after processing. > +Default is 2. Range is from 1 and 64. "Amount" -> "Number" (not sure about this one, "number" seems more correct to me personally) > +of @code{rms}. Default is @code{rms} which is mainly smoother. "mainly"? (i.e. its main effect) -> "mostly"? (i.e. more often?) Moritz _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel