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• Uploading videos on rails website

  16 mai 2017, par Dinukaperera

  I am trying to let my users upload videos on my website(not deployed yet, testing locally). I have it set up in a manner where if the "user information" gets saved, it will take them to the "root_path", which is the homepage. If the user information is not saved, it will render the form again. Before I added the video upload feature, all the information got saved and everything worked well, but after adding the feature, it keeps rendering the same form over and over again since the information is not getting saved. How do I check what’s wrong ? The command line gives me this error :

  The user information form partial :
  `

  <%= simple_form_for @userinfo do |f| %>
  
    <%= f.input :name, label: 'Full name', error: 'Full name is mandatory' %>
  
    <%= f.input :username, label: 'Username', error: 'Username is mandatory, please specify one' %>
  
    <%= f.input :school, label: 'Name of college' %>
  
    <%= f.input :gpa, label: 'Enter GPA' %>
  
    <%= f.input :email, label: 'Enter email address' %>
  
    <%= f.input :number, label: 'Phone number' %>
  
    <%= f.file_field :video %>
  
    <%= f.button :submit %>
  
  <% end %>

  `

  My user controller (This is the user information controller, does not control user email and password. I’m using the devise gem for user sign in, sign out, and sign up) :`

  class UsersController < ApplicationController
  
      def index
  
      end
  
  
  
      def show
  
      end
  
  
  
      def new
  
          @userinfo = User.new
  
      end
  
  
  
      def create
  
          @userinfo = User.new(user_params)
  
          if @userinfo.save
  
            redirect_to root_path
  
          else
  
            render 'new'
  
          end
  
      end
  
  
  
      def edit
  
      end
  
  
  
      def update
  
      end
  
  
  
      def destroy
  
      end
  
  
  
      private
  
          def user_params
  
              params.require(:user).permit(:name, :username, :email, :number, :school, :gpa, :major, :video)
  
          end
  
  end

  `

  This is the user model (usermain is the model related to user password and email. The user information in the user model belongs to the usermain) : `

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

  `

  This is the migration file that creates the user information table :`

  class CreateUsers < ActiveRecord::Migration
  
    def change
  
      create_table :users do |t|
  
        t.string :name
  
        t.string :username
  
        t.string :email
  
        t.string :number
  
        t.string :school
  
        t.string :gpa
  
        t.string :major
  
  
  
        t.timestamps null: false
  
      end
  
    end
  
  end

  This is adding the "video" field to the above created user information table:

  class AddAttachmentVideoToUsers < ActiveRecord::Migration
  
    def self.up
  
      change_table :users do |t|
  
        t.attachment :video
  
      end
  
    end
  
  
  
    def self.down
  
      remove_attachment :users, :video
  
    end
  
  end

  `

  I also have paperclip and ffmpeg installed. When I say installed, it’s literally just that. I’m not sure if I have to manipulate paperclip or ffmpeg in any way to make it work with the videos, I have just installed and did nothing else with them. I have been pulling my hair out for the past two days. Any help is appreciated.

• Using Pipes for Stream Data in FFMPEG

  17 juillet 2024, par Aryan Kumar

  I am trying to input stream and decrease the bitrate of the video without saving it anywhere so i am hoping to pass it as a stream and get the output as a stream and send it to digital ocean spaces to get saved.
But I tried lots of things but my output Stream is getting empty. and the file is empty.

  


      public async Task VideoOperationAsync(Stream inputStream)
    {
        try
        {
            // Ensure the input stream is at the beginning
            inputStream.Position = 0;

            // Create a memory stream to hold the output data
            using (var outputStream = new MemoryStream())
            {
                var arguments = $"-i pipe:0 -f mp4 pipe:1";

                await Cli.Wrap("ffmpeg")
                    .WithArguments(arguments)
                    .WithStandardInputPipe(PipeSource.FromStream(inputStream))
                    .WithStandardOutputPipe(PipeTarget.ToStream(outputStream))
                    .WithValidation(CommandResultValidation.None)
                    .ExecuteAsync();

                // Ensure the output stream is at the beginning before reading
                outputStream.Position = 0;

                using (var fileStream = new FileStream(@"D:\Gremlin-data\VideoResized\output_cropped.mp4", FileMode.Create, FileAccess.Write))
                {
                    await outputStream.CopyToAsync(fileStream);
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred: {ex.Message}");
            throw;  // Re-throw the exception if needed
        }
    }


  


  I also earlier tried this :

  


  public async Task VideoOperationAsync(Stream inputStream)

try

// Ensure the input stream is at the beginning
inputStream.Position = 0 ;

  


          var ffmpegProcess = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = "ffmpeg",  // Ensure ffmpeg is in your PATH or provide the full path
                Arguments = $"-i pipe:0 -b:v 2000k -f mp4 pipe:1",  // Correct bitrate format
                RedirectStandardInput = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true,  // Capture standard error
                UseShellExecute = false,
                CreateNoWindow = true
            }
        };

        ffmpegProcess.Start();

        // Write input stream to ffmpeg's standard input asynchronously
        Task writingTask = Task.Run(async () =>
        {
            await inputStream.CopyToAsync(ffmpegProcess.StandardInput.BaseStream);
            ffmpegProcess.StandardInput.BaseStream.Close();
        });

        // Read ffmpeg's standard output to a memory stream asynchronously
        using (MemoryStream ms = new MemoryStream())
        {
            Task readingTask = Task.Run(async () =>
            {
                await ffmpegProcess.StandardOutput.BaseStream.CopyToAsync(ms);
            });


  


• VP8 Misplaced Plane

  16 octobre 2010, par Multimedia Mike — VP8

  So I’m stubbornly plugging away at my toy VP8 encoder and I managed to produce this gem. See if you can spot the subtle mistake :

  
  
  

  The misplaced color plane resulted from using the luma plane stride where it was not appropriate. I fixed that and now chroma planes are wired to use to the same naive prediction algorithm as the luma plane.

  Also, I fixed the entropy encoder so that end of block conditions are signaled correctly (instead of my original, suboptimal hack to just encode all zeros). I was disappointed to see that this did not result in a major compression improvement. Then again, I’m using the lowest possible quantization settings for this outing, so perhaps this is to be expected.

  Sigh… 4×4 luma prediction is next. Wish me luck.