Paperclip支持图片和视频吗？

Question

在我的应用程序中，我已经使用了paperclip来上传图像，但需求已更改，需要接受图像和视频。这些图像已经在一个使用belongs_to关系定义的模型中，名为Attachment。由于视频也将成为同一父模型（在我的情况下是文章）的附件，因此我希望重用相同的Attachment模型来处理图像和视频。这样做是否明智？

我的attachment.rb代码如下：

class Attachment < ActiveRecord::Base

  belongs_to :article 

  has_attached_file :url, :s3_protocol => :https , 
    styles: { 
      medium: "300x300>", thumb: "100x100>", big: "1200x1200>", normal: "600x600>" 
    }

  validates_attachment_content_type :url, content_type: /\Aimage|\Avideo\/.*\Z/

  validates_attachment :url, content_type: { content_type: ["image/jpeg", "image/gif", "image/png", "video/mp4"] }

end

但事实上，它并没有将视频存储在S3上。我在终端中看到了以下内容。

Command :: file -b --mime '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/f3e2afc957bb9fb2aa3e77e69359c48920160131-13311-pyeez1.mp4'
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/8dc7385648e2164764b72fda6fd9099a20160131-13311-1l40ccn.mp4[0]' 2>/dev/null
[paperclip] An error was received while processing: #<Paperclip::Errors::NotIdentifiedByImageMagickError: Paperclip::Errors::NotIdentifiedByImageMagickError>
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/8dc7385648e2164764b72fda6fd9099a20160131-13311-1l40ccn.mp4[0]' 2>/dev/null
[paperclip] An error was received while processing: #<Paperclip::Errors::NotIdentifiedByImageMagickError: Paperclip::Errors::NotIdentifiedByImageMagickError>
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/8dc7385648e2164764b72fda6fd9099a20160131-13311-1l40ccn.mp4[0]' 2>/dev/null
[paperclip] An error was received while processing: #<Paperclip::Errors::NotIdentifiedByImageMagickError: Paperclip::Errors::NotIdentifiedByImageMagickError>
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/8dc7385648e2164764b72fda6fd9099a20160131-13311-1l40ccn.mp4[0]' 2>/dev/null
[paperclip] An error was received while processing: #<Paperclip::Errors::NotIdentifiedByImageMagickError: Paperclip::Errors::NotIdentifiedByImageMagickError>
Command :: file -b --mime '/var/folders/v_/pf2bsxnj1y37ccd2pjksv7z80000gn/T/f3e2afc957bb9fb2aa3e77e69359c48920160131-13311-kvb5nr.mp4'

第二个问题是，由于我在前端使用AngularJS，那我是否可以利用HTML的<video>标签将视频呈现给用户？

- tvieira

---

你是如何转码视频的？ - Richard Peck

Answer 1

看起来问题在于ImageMagick试图对视频进行转码，但它无法完成。

处理Paperclip中视频的转码的方法是使用paperclip-av-transcoder gem（以前是paperclip-ffmpeg）。我只有使用后者的经验：

#app/models/attachment.rb
class Attachment < ActiveRecord::Base
    has_attached_file :url, :s3_protocol => :https , 
       styles:  lambda { |a| a.instance.is_image? ?  medium: "300x300>", thumb: "100x100>", big: "1200x1200>", normal: "600x600>" } : {:thumb => { :geometry => "100x100#", :format => 'jpg', :time => 10}, :medium => { :geometry => "300x300#", :format => 'jpg', :time => 10}}}, processors: [:transcoder]

    validates_attachment :url,
        content_type: ['video/mp4'],
        message:      "Sorry, right now we only support MP4 video",
        if:           :is_video?

    validates_attachment :url,
        content_type: ['image/png', 'image/jpeg', 'image/jpg', 'image/gif'],
        message:      "Different error message",
        if:           :is_image?

  private

  def is_video?
    url.instance.attachment_content_type =~ %r(video)
  end

  def is_image?
    url.instance.attachment_content_type =~ %r(image)
  end
end

我们的旧代码 & 参考

- Richard Peck

---

以上代码存在两个问题。第一个问题是在 medium: "300x300>" 之前应该有一个 { 来标记哈希的开始。第二个问题是 processors: [:transcoder] 标志将在所有上传文件上运行转码器，而不仅仅是视频，因此当您将图像发送给 ffmpeg 时，它将失败。 - Eric Smith