使用Rails上传和转换视频

前提是需要安装FFMPEG，实现视频转换和上传我们需要一些插件


Paperclip

没什么好多说，历史的选择，上传还是这个
Github

Acts As State Machine


状态机支持，也经常用到
关于状态机，这个讨论很有味道，建议了解

ruby script/plugin install 

创建Model
First off, let’s create our video model. We’ll call it video. Inventive, eh?

ruby script/generate model video

可以看到代码生成如下：

class Video < ActiveRecord::Base
  # Paperclip
  # http://www.thoughtbot.com/projects/paperclip
  has_attached_file :source

  # Paperclip Validations
  validates_attachment_presence :source
  validates_attachment_content_type :source, :content_type => 'video/quicktime'
end

使用过Paperclip，会习惯用source保存上传的大文件
添加状态

  # Acts as State Machine
  # http://elitists.textdriven.com/svn/plugins/acts_as_state_machine
  acts_as_state_machine :initial => :pending
  state :pending
  state :converting
  state :converted, :enter => :set_new_filename
  state :error

  event :convert do
    transitions :from => :pending, :to => :converting
  end

  event :converted do
    transitions :from => :converting, :to => :converted
  end

  event :failed do
    transitions :from => :converting, :to => :error
  end

运行 Migrations
migration文件如下：

class CreateVideos < ActiveRecord::Migration
  def self.up
    create_table :videos do |t|
      t.string :source_content_type
      t.string :source_file_name
      t.integer :source_file_size
      t.string :state
      t.timestamps
    end
  end

  def self.down
    drop_table :videos
  end
end

其中source_ 是用来给Paperclip上传文件， state字段是给acts_as_state_machine

运行命令如下：

rake db:migrate

添加转换方法


在 video.rb文件中添加如下方法用来处理转换

  # This method is called from the controller and takes care of the converting
  def convert
    self.convert!
    success = system(convert_command)
    if success && $?.exitstatus == 0
      self.converted!
    else
      self.failure!
    end
  end

  protected

  # This method creates the ffmpeg command that we'll be using
  def convert_command
    flv = File.join(File.dirname(source.path), "#{id}.flv")
    File.open(flv, 'w')

    command = <<-end_command
      ffmpeg -i #{ source.path }  -ar 22050 -ab 32 -acodec mp3
      -s 480x360 -vcodec flv -r 25 -qscale 8 -f flv -y #{ flv }
    end_command
    command.gsub!(/\s+/, " ")
  end

  # This update the stored filename with the new flash video file
  def set_new_filename
    update_attribute(:source_file_name, "#{id}.flv")
  end

控制器中

控制器将如下，上传的view比较容易，唯一注意的是应该给form注明:multipart => true

class VideosController < ApplicationController
  def index
    @videos = Video.find :all
  end

  def new
    @video = Video.new
  end

  def create
    @video = Video.new(params[:video])
    if @video.save
      @video.convert
      flash[:notice] = 'Video has been uploaded'
      redirect_to :action => 'index'
    else
      render :action => 'new'
    end
  end

  def show
    @video = Video.find(params[:id])
  end
end

引用

After the video is saved in the create method, the convert method is called. This should convert the video to a flash video file, update the database entry and set the state of the model. The state will be set to converted if everything went to plan, or error if everything went to shit.

完整的video.rb文件可以看这里

在页面显示视频


显示视频的方案当前有两个

SWFObject

JW FLV Media Player

前者是javascript的嵌入Adobe Flash，优势是搜索支持，后者支持多种转换格式FLV, but also MP3, H264, SWF, JPG, PNG and GIF)。


介绍后一个要加载 swfobject.js文件

<%= javascript_include_tag 'swfobject' %>

将mediaplayer.swf放到public/flash/mediaplayer.swf

<div id="player">
  You need to have <%= link_to 'Flash Player', 'http://www.adobe.com/shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash' %> installed to display this video
</div>

<script type="text/javascript">
  var so = new SWFObject('/flash/mediaplayer.swf', 'mpl', '480', '360', '8');
  so.addParam('allowscriptaccess', 'always');
  so.addParam('allowfullscreen', 'true');
  so.addVariable('height', '360');
  so.addVariable('width', '480');
  so.addVariable('file', '<%= @video.source.url %>');
  so.write('player');
</script>

引用

The contents of the div will be replaced with the flash player, if flash isn't installed the user is shown a message with a link to download flash player. The <%= @video.source.url %> line will output the path to the flv video file.

标准的JW FLV Player安装介绍


最后，

使用rails转换视频之 安装FFMPEG

评论

1 楼 fireflyman 2010-08-25  

awesome