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Filename : recipes.js
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/*jshint node:true*/
'use strict';

var fs = require('fs');
var path = require('path');
var PassThrough = require('stream').PassThrough;
var async = require('async');
var utils = require('./utils');


/*
 * Useful recipes for commands
 */

module.exports = function recipes(proto) {
  /**
   * Execute ffmpeg command and save output to a file
   *
   * @method FfmpegCommand#save
   * @category Processing
   * @aliases saveToFile
   *
   * @param {String} output file path
   * @return FfmpegCommand
   */
  proto.saveToFile =
  proto.save = function(output) {
    this.output(output).run();
    return this;
  };


  /**
   * Execute ffmpeg command and save output to a stream
   *
   * If 'stream' is not specified, a PassThrough stream is created and returned.
   * 'options' will be used when piping ffmpeg output to the output stream
   * (@see http://nodejs.org/api/stream.html#stream_readable_pipe_destination_options)
   *
   * @method FfmpegCommand#pipe
   * @category Processing
   * @aliases stream,writeToStream
   *
   * @param {stream.Writable} [stream] output stream
   * @param {Object} [options={}] pipe options
   * @return Output stream
   */
  proto.writeToStream =
  proto.pipe =
  proto.stream = function(stream, options) {
    if (stream && !('writable' in stream)) {
      options = stream;
      stream = undefined;
    }

    if (!stream) {
      if (process.version.match(/v0\.8\./)) {
        throw new Error('PassThrough stream is not supported on node v0.8');
      }

      stream = new PassThrough();
    }

    this.output(stream, options).run();
    return stream;
  };


  /**
   * Generate images from a video
   *
   * Note: this method makes the command emit a 'filenames' event with an array of
   * the generated image filenames.
   *
   * @method FfmpegCommand#screenshots
   * @category Processing
   * @aliases takeScreenshots,thumbnail,thumbnails,screenshot
   *
   * @param {Number|Object} [config=1] screenshot count or configuration object with
   *   the following keys:
   * @param {Number} [config.count] number of screenshots to take; using this option
   *   takes screenshots at regular intervals (eg. count=4 would take screens at 20%, 40%,
   *   60% and 80% of the video length).
   * @param {String} [config.folder='.'] output folder
   * @param {String} [config.filename='tn.png'] output filename pattern, may contain the following
   *   tokens:
   *   - '%s': offset in seconds
   *   - '%w': screenshot width
   *   - '%h': screenshot height
   *   - '%r': screenshot resolution (same as '%wx%h')
   *   - '%f': input filename
   *   - '%b': input basename (filename w/o extension)
   *   - '%i': index of screenshot in timemark array (can be zero-padded by using it like `%000i`)
   * @param {Number[]|String[]} [config.timemarks] array of timemarks to take screenshots
   *   at; each timemark may be a number of seconds, a '[[hh:]mm:]ss[.xxx]' string or a
   *   'XX%' string.  Overrides 'count' if present.
   * @param {Number[]|String[]} [config.timestamps] alias for 'timemarks'
   * @param {Boolean} [config.fastSeek] use fast seek (less accurate)
   * @param {String} [config.size] screenshot size, with the same syntax as {@link FfmpegCommand#size}
   * @param {String} [folder] output folder (legacy alias for 'config.folder')
   * @return FfmpegCommand
   */
  proto.takeScreenshots =
  proto.thumbnail =
  proto.thumbnails =
  proto.screenshot =
  proto.screenshots = function(config, folder) {
    var self = this;
    var source = this._currentInput.source;
    config = config || { count: 1 };

    // Accept a number of screenshots instead of a config object
    if (typeof config === 'number') {
      config = {
        count: config
      };
    }

    // Accept a second 'folder' parameter instead of config.folder
    if (!('folder' in config)) {
      config.folder = folder || '.';
    }

    // Accept 'timestamps' instead of 'timemarks'
    if ('timestamps' in config) {
      config.timemarks = config.timestamps;
    }

    // Compute timemarks from count if not present
    if (!('timemarks' in config)) {
      if (!config.count) {
        throw new Error('Cannot take screenshots: neither a count nor a timemark list are specified');
      }

      var interval = 100 / (1 + config.count);
      config.timemarks = [];
      for (var i = 0; i < config.count; i++) {
        config.timemarks.push((interval * (i + 1)) + '%');
      }
    }

    // Parse size option
    if ('size' in config) {
      var fixedSize = config.size.match(/^(\d+)x(\d+)$/);
      var fixedWidth = config.size.match(/^(\d+)x\?$/);
      var fixedHeight = config.size.match(/^\?x(\d+)$/);
      var percentSize = config.size.match(/^(\d+)%$/);

      if (!fixedSize && !fixedWidth && !fixedHeight && !percentSize) {
        throw new Error('Invalid size parameter: ' + config.size);
      }
    }

    // Metadata helper
    var metadata;
    function getMetadata(cb) {
      if (metadata) {
        cb(null, metadata);
      } else {
        self.ffprobe(function(err, meta) {
          metadata = meta;
          cb(err, meta);
        });
      }
    }

    async.waterfall([
      // Compute percent timemarks if any
      function computeTimemarks(next) {
        if (config.timemarks.some(function(t) { return ('' + t).match(/^[\d.]+%$/); })) {
          if (typeof source !== 'string') {
            return next(new Error('Cannot compute screenshot timemarks with an input stream, please specify fixed timemarks'));
          }

          getMetadata(function(err, meta) {
            if (err) {
              next(err);
            } else {
              // Select video stream with the highest resolution
              var vstream = meta.streams.reduce(function(biggest, stream) {
                if (stream.codec_type === 'video' && stream.width * stream.height > biggest.width * biggest.height) {
                  return stream;
                } else {
                  return biggest;
                }
              }, { width: 0, height: 0 });

              if (vstream.width === 0) {
                return next(new Error('No video stream in input, cannot take screenshots'));
              }

              var duration = Number(vstream.duration);
              if (isNaN(duration)) {
                duration = Number(meta.format.duration);
              }

              if (isNaN(duration)) {
                return next(new Error('Could not get input duration, please specify fixed timemarks'));
              }

              config.timemarks = config.timemarks.map(function(mark) {
                if (('' + mark).match(/^([\d.]+)%$/)) {
                  return duration * parseFloat(mark) / 100;
                } else {
                  return mark;
                }
              });

              next();
            }
          });
        } else {
          next();
        }
      },

      // Turn all timemarks into numbers and sort them
      function normalizeTimemarks(next) {
        config.timemarks = config.timemarks.map(function(mark) {
          return utils.timemarkToSeconds(mark);
        }).sort(function(a, b) { return a - b; });

        next();
      },

      // Add '_%i' to pattern when requesting multiple screenshots and no variable token is present
      function fixPattern(next) {
        var pattern = config.filename || 'tn.png';

        if (pattern.indexOf('.') === -1) {
          pattern += '.png';
        }

        if (config.timemarks.length > 1 && !pattern.match(/%(s|0*i)/)) {
          var ext = path.extname(pattern);
          pattern = path.join(path.dirname(pattern), path.basename(pattern, ext) + '_%i' + ext);
        }

        next(null, pattern);
      },

      // Replace filename tokens (%f, %b) in pattern
      function replaceFilenameTokens(pattern, next) {
        if (pattern.match(/%[bf]/)) {
          if (typeof source !== 'string') {
            return next(new Error('Cannot replace %f or %b when using an input stream'));
          }

          pattern = pattern
            .replace(/%f/g, path.basename(source))
            .replace(/%b/g, path.basename(source, path.extname(source)));
        }

        next(null, pattern);
      },

      // Compute size if needed
      function getSize(pattern, next) {
        if (pattern.match(/%[whr]/)) {
          if (fixedSize) {
            return next(null, pattern, fixedSize[1], fixedSize[2]);
          }

          getMetadata(function(err, meta) {
            if (err) {
              return next(new Error('Could not determine video resolution to replace %w, %h or %r'));
            }

            var vstream = meta.streams.reduce(function(biggest, stream) {
              if (stream.codec_type === 'video' && stream.width * stream.height > biggest.width * biggest.height) {
                return stream;
              } else {
                return biggest;
              }
            }, { width: 0, height: 0 });

            if (vstream.width === 0) {
              return next(new Error('No video stream in input, cannot replace %w, %h or %r'));
            }

            var width = vstream.width;
            var height = vstream.height;

            if (fixedWidth) {
              height = height * Number(fixedWidth[1]) / width;
              width = Number(fixedWidth[1]);
            } else if (fixedHeight) {
              width = width * Number(fixedHeight[1]) / height;
              height = Number(fixedHeight[1]);
            } else if (percentSize) {
              width = width * Number(percentSize[1]) / 100;
              height = height * Number(percentSize[1]) / 100;
            }

            next(null, pattern, Math.round(width / 2) * 2, Math.round(height / 2) * 2);
          });
        } else {
          next(null, pattern, -1, -1);
        }
      },

      // Replace size tokens (%w, %h, %r) in pattern
      function replaceSizeTokens(pattern, width, height, next) {
        pattern = pattern
          .replace(/%r/g, '%wx%h')
          .replace(/%w/g, width)
          .replace(/%h/g, height);

        next(null, pattern);
      },

      // Replace variable tokens in pattern (%s, %i) and generate filename list
      function replaceVariableTokens(pattern, next) {
        var filenames = config.timemarks.map(function(t, i) {
          return pattern
            .replace(/%s/g, utils.timemarkToSeconds(t))
            .replace(/%(0*)i/g, function(match, padding) {
              var idx = '' + (i + 1);
              return padding.substr(0, Math.max(0, padding.length + 1 - idx.length)) + idx;
            });
        });

        self.emit('filenames', filenames);
        next(null, filenames);
      },

      // Create output directory
      function createDirectory(filenames, next) {
        fs.exists(config.folder, function(exists) {
          if (!exists) {
            fs.mkdir(config.folder, function(err) {
              if (err) {
                next(err);
              } else {
                next(null, filenames);
              }
            });
          } else {
            next(null, filenames);
          }
        });
      }
    ], function runCommand(err, filenames) {
      if (err) {
        return self.emit('error', err);
      }

      var count = config.timemarks.length;
      var split;
      var filters = [split = {
        filter: 'split',
        options: count,
        outputs: []
      }];

      if ('size' in config) {
        // Set size to generate size filters
        self.size(config.size);

        // Get size filters and chain them with 'sizeN' stream names
        var sizeFilters =  self._currentOutput.sizeFilters.get().map(function(f, i) {
          if (i > 0) {
            f.inputs = 'size' + (i - 1);
          }

          f.outputs = 'size' + i;

          return f;
        });

        // Input last size filter output into split filter
        split.inputs = 'size' + (sizeFilters.length - 1);

        // Add size filters in front of split filter
        filters = sizeFilters.concat(filters);

        // Remove size filters
        self._currentOutput.sizeFilters.clear();
      }

      var first = 0;
      for (var i = 0; i < count; i++) {
        var stream = 'screen' + i;
        split.outputs.push(stream);

        if (i === 0) {
          first = config.timemarks[i];
          self.seekInput(first);
        }

        self.output(path.join(config.folder, filenames[i]))
          .frames(1)
          .map(stream);

        if (i > 0) {
          self.seek(config.timemarks[i] - first);
        }
      }

      self.complexFilter(filters);
      self.run();
    });

    return this;
  };


  /**
   * Merge (concatenate) inputs to a single file
   *
   * @method FfmpegCommand#concat
   * @category Processing
   * @aliases concatenate,mergeToFile
   *
   * @param {String|Writable} target output file or writable stream
   * @param {Object} [options] pipe options (only used when outputting to a writable stream)
   * @return FfmpegCommand
   */
  proto.mergeToFile =
  proto.concatenate =
  proto.concat = function(target, options) {
    // Find out which streams are present in the first non-stream input
    var fileInput = this._inputs.filter(function(input) {
      return !input.isStream;
    })[0];

    var self = this;
    this.ffprobe(this._inputs.indexOf(fileInput), function(err, data) {
      if (err) {
        return self.emit('error', err);
      }

      var hasAudioStreams = data.streams.some(function(stream) {
        return stream.codec_type === 'audio';
      });

      var hasVideoStreams = data.streams.some(function(stream) {
        return stream.codec_type === 'video';
      });

      // Setup concat filter and start processing
      self.output(target, options)
        .complexFilter({
          filter: 'concat',
          options: {
            n: self._inputs.length,
            v: hasVideoStreams ? 1 : 0,
            a: hasAudioStreams ? 1 : 0
          }
        })
        .run();
    });

    return this;
  };
};