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• Getting error on video with Ruby on Rails 4 App

  30 avril 2016, par D.Graves

  So this is the error I get right after I try and upload my video

  

  This is my post show

  <%= video_tag @post.video.url(:medium), controls: true, style: "max-width: 100%;" %>
  
  
  
  <p>
  
    <strong>Description:</strong>
  
  &lt;%= @post.description %>
  
  </p>
  
    &lt;% if @post.user == current_user %>
  
    &lt;%= link_to 'Edit', edit_post_path(@post) %> 
  
  &lt;% end %>|
  
  &lt;%= link_to 'Back', posts_path %>

  This is my post model

  class Post < ActiveRecord::Base
  
   belongs_to :user
  
  
  
   has_attached_file :video, styles: {
  
      :medium => {
  
        :geometry => "640x480",
  
        :format => 'mp4'
  
      },
  
      :thumb => { :geometry => "160x120", :format => 'jpeg', :time => 10}
  
  }, :processors => [:transcoder]
  
  validates_attachment_content_type :video, content_type: /\Avideo\/.*\Z/
  
  end

  I am curious if anyone has run into this before and I am wondering if I can get any help on how to fix this. I am using paperclip av-transcoder gem, ffmpeg and paperclip gem. I can add any more information if needed

  Here is my post controller if this helps

  def index
  
  @posts = Post.all
  
  end
  
  
  
  def show
  
  end
  
  
  
  def new
  
  @post = current_user.posts.build
  
  end
  
  
  
  def edit
  
  end
  
  
  
  def create
  
  @post = current_user.posts.build(post_params)
  
  if @post.save
  
    redirect_to @post, notice: 'Post was successfully created.'
  
  else
  
    render :new
  
  end
  
  end
  
  
  
  def update
  
  if @post.update(post_params)
  
    redirect_to @post, notice: 'Post was successfully updated.'
  
  else
  
    render :edit
  
  end
  
  end
  
  
  
  def destroy
  
  @post.destroy
  
  redirect_to posts_url
  
  end
  
  
  
  private
  
  def set_post
  
    @post = Post.find_by(id: params[:id])
  
  end
  
  
  
  def correct_user
  
    @post = current_user.posts.find_by(id: params[:id])
  
    redirect_to posts_path, notice: "Not authorized to edit this post" if @post.nil?
  
  end
  
  
  
  def post_params
  
    params.require(:post).permit(:description, :video)
  
  end
  
  
  
  
  
   end

• How to process video stream ?

  27 avril 2016, par sharpener

  I would like to ask some experienced multimedia professional how to proceed with following task :

  Given URL provides video stream and we would like to get access to decoded frames (byte stream in memory) in managed Win7+ application (C#). We don’t want to render/present the frames the standard way. The video format is known but not fixed (might get changed between two successive sessions, but we will know the parameters).

  So far, I have found there are several methods and I have build following picture in my mind :

  1. ffmpeg wrapper
     • Pros
       1. Self contained (no dependency to windows technologies)
       2. Powerful
     • Cons
       1. Little more complex to understand
       2. Lot of different wrapping variants (FFmpeg.NET, ffmpeg-sharp, ffmpeg-shard, FFmpeg.AutoGen, ...)
  2. DirectShow wrapper
     • Pros
       1. Widely used/supported technology (variaous filters freely available)
       2. Nice/detailed documentation on MSDN
     • Cons
       1. Quite old
       2. Considered obsolete from the point of author’s view (available only for desktop model on runtime >= Win8)
  3. MediaFoundation wrapper
     • Pros
       1. Theoretical successor of DirectShow, so should be available in the future
     • Cons
       1. Seems to be not as good as DirectShow
       2. Not very popular, limited "community" support
  4. FFmpegInterop wrapper
     • Pros
       1. Microsoft’s open source wrapper alternative
     • Cons
       1. Not available for runtime < Win8

• ffmpeg 2.8.x cross compile error on mac os x 10.10

  22 avril 2016, par alijandro

  I want to cross compile ffmpeg 2.8.x on Mac OS X 10.10, but I got the following error.

  HOSTCC  libavcodec/cabac_tablegen.o
  
  In file included from libavcodec/cabac_tablegen.c:25:
  
  In file included from libavcodec/cabac_functions.h:43:
  
  libavcodec/arm/cabac.h:96:25: error: value '24' out of range for constraint 'M'
  
            [byte]"M"(offsetof(CABACContext, bytestream)),
  
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/7.0.2/include/stddef.h:120:24: note: 
  
    expanded from macro 'offsetof'
  
  #define offsetof(t, d) __builtin_offsetof(t, d)
  
                     ^~~~~~~~~~~~~~~~~~~~~~~~
  
  1 error generated.
  
  make: *** [libavcodec/cabac_tablegen.o] Error 1

  The error show some error in host cc, the host cc is clang-700.1.81

  $ gcc --version
  
  Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
  
  Apple LLVM version 7.0.2 (clang-700.1.81)
  
  Target: x86_64-apple-darwin14.5.0
  
  Thread model: posix

  Before I upgrade Xcode to 7.2, it worked fine.

  For ffmpeg 3.x, there is no such problem. But the ffmpeg version I need is 2.8.x. How can I fix without downgrade Xcode to previous version ?