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aselect.js
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const addFilter = require('./utils').addFilter;
const registerFilter = require('./utils').registerFilter;
/**
* Augment FfmpegCommand with the aselect function.
*
*
* @example
* ffmpeg().aselect()
* ... // call filter configuration functions
* .build() // end filter configuration
* ...
* .applyFilters() // called once all filters have been configured
*
* @param {FfmpegCommand} ffmpegCommand The fluent-ffmpeg constructor.
* @return {FfmpegCommand} The ffmpegCommand augmented with the aselect function.
*/
function aselect(ffmpegCommand) {
registerFilter(ffmpegCommand, 'aselect', function() {
return new AselectFilter(this);
});
return ffmpegCommand;
}
/**
* Class exposing methods to configure the vstack filter in a builder pattern way.
*
* See {@link http://ffmpeg.org/ffmpeg-filters.html#vstack} for a description
* of each configuration option.
*/
class AselectFilter {
/**
* @param {FfmpegCommand} ffmpegCommand The fluent-ffmpeg constructor.
*/
constructor (ffmpeg) {
this.ffmpeg = ffmpeg;
AselectFilter.prototype.withExpr = this.expr;
AselectFilter.prototype.withOutputs = this.outputs;
}
/**
* Set expression, which is evaluated for each input frame.
*
* If the expression is evaluated to zero, the frame is discarded.
*
* If the evaluation result is negative or NaN, the frame is sent to the
* first output; otherwise it is sent to the output with index
* ceil(val)-1, assuming that the input index starts from 0.
*
* For example a value of 1.2 corresponds to the output with index
* ceil(1.2)-1 = 2-1 = 1, that is the second output.
*
*
* @param val
*/
expr(val) {
this._expr = val;
return this;
}
/**
* Set the number of outputs. The output to which to send the selected
* frame is based on the result of the evaluation. Default value is 1.
*
* @param val
*/
outputs(val) {
this._outputs = val;
return this;
}
/**
* Creates this filter configuration and registers it in the ffmpeg instance.
* @return {ffmpegCommand} The ffmpeg instance.
*/
build() {
let opt = {};
if (this._expr) {
opt['expr'] = this._expr;
}
if (this._outputs) {
opt['outputs'] = this._outputs;
}
addFilter(this.ffmpeg, {
filter: 'aselect',
options: opt
});
return this.ffmpeg;
}
}
module.exports.aselect = aselect;