Revision as of 20:54, 6 August 2006

Introduction

What is Rubyripper? Rubyripper is a digital audio extraction algorithm that uses cdparanoia or cdda2wav in a sophisticated way to make sure that a CD rip is done succesfully and accurately. It is very similiar to and inspired by EAC. Rubyripper is written in the ruby programming language.

It's currently available for Linux (partial BSD support). OS X will most likely be supported in the near future. The source (same as executable) is published under the GPL license.

• UPDATE: New version 0.2 was released on 4 August 2006.
• UPDATE: New version 0.1.1 was released on 12 February 2006.
• UPDATE: New version 0.1.0 was released on 5 November 2005.

Features

• A GTK2 user interface
• Sophisticated error correction mechanism
• A command line interface (CLI) available
• CDDB-info is fetched via the ruby-freedb module
• Info can be edited after fetching
• The codecs supported are FLAC, Vorbis, MP3, and Wav
• Multiple codecs can be used in one run
• Direct offset support
• Detailed logfile creation
• A detailed overview of hard-to-correct positions
• Create m3u playlists

Correction mechanism

Rubyripper correction mechanism goes beyond that of cdparanoia. Every track gets ripped at least twice and is byte compared with the Ruby cmp feature. If any differences are found, each of the 1,000 bytes of the two files is compared. The next trial run looks to see if differing positions or a match can be found. (1,000 bytes is about 0.006 seconds)

The main underlying Philosophy is that an erronous read of an underlying ripper will produce random results. This seems so far to be correct. A possibility still exists that with randomn results the same result will be wrong.

If the full 1,000 bytes are erronous, than a false repair seems to be highly unlikely since there are possibilities in theory. (As a byte consists of 8 bits, 2⁸=256). This would need an infinite amount of trials to match. The main principle however is, the more trials that are needed, consequently the higher a chance of a false repair.

Suppose only 3 bytes in a sample of 1,000 bytes give random information. This would still mean possibilities within each of these bytes, really 2 bits could be a problem. This reduces the possibilities to possibilies. So, a false repair still seems to be possible. One has to wonder though: can 3 bytes actually be heard in a wav file that produces 180.000 bytes per second?

In conclusion: Rubyripper won't guarantee a consequent MD5-sum on tracks that needed correction. However it will repair any files so that it's impossible to succesfully blind-test with the original. The log file will report any position that needed more than 3 trials, so you can check the position yourself.

Installation

Make sure to have ruby-freedb, ruby-libglade2 and cdparanoia or cdda2wav installed as a minimum. You can optionally choose for Lame, Vorbis or FLAC, depending on the codec you wish to use.

Then download Rubyripper: http://rubyforge.org/frs/?group_id=1284&release_id=6293

Documentation of some of the ripping logic used can be found at: (somewhat dated)
http://rubyforge.org/docman/view.php/1284/310/Rubyripper's%20ripping%20logic.pdf

Currently there isn't an official installer available. Usage from a terminal or console:

cd <download_dir> (Go to the directory where you saved the downloaded archive)

tar xfj <filename_download> (Unpack the archive)

cd rubyripper-<version> (Move into the just unpacked directory)

chmod +x *.rb (Make all .rb files executable)

./rubyripper_gtk.rb (Launch gtk2 user interface)

./rubyripper_cli.rb (Launch command line user interface)

If Rubyripper doesn't start make sure the dependencies are ok. When launched from a terminal rubyripper should now tell which dependency it's missing.

Screenshots

The theme used in the screenshots is GTK-Qt-theme.

• The Cddb-info tab
• The Codecs tab
• The Other settings tab
• The Ripping settings tab
• The status tab

Suggestions for next version

• Try to rip only parts that contain errors to save time
• Erronous parts should be matched more than once
• OS X support. As the only developer I need some help, for I don't have a Mac. A Mac user could help to get the cli-version working. A ruby programmer could help to make the GUI for OS X. I'll be glad to add support for this task.
• Let the user choose which freedb hit he/she will use

Known Bugs

• If the first trial of a track has a different size than the second track, it assumes that the size of the first track is right. We don't know that for sure.

External links

• Rubyripper the official Rubyforge website
• Hydrogenaudio forum thread the first public release of Rubyripper

Developer info

This section will give some technical information, which should be usefull for interested developers. It will outline how the code is structured and what the API of the Rubyripper codebase is for adding new user interfaces. Since version 0.2 it is quite simply to add new frontends to the current codebase. Currently there is a CLI and a GTK2 frontend. But a Qt frontend or a Cocoa Mac OS frontend isn't terribly difficult to achieve. I won't implement this myself though, as I'm more interested to finetune the Rubyripper codebase.

Becoming a developer

To become a developer you should have:

• Some basic knowledge of the Ruby programming language. Read for instance the free online book, at least until the chapter Until trouble strikes. This is a somewhat dated version, but still perfectly usable. As I don't use any new features I think it should be fine.
• Some basic knowledge of a gui-toolkit in case you want to add a new frontend.

Rubyripper files and classes

The 0.2 release has three ruby files and one glade file included:

• rr_lib.rb. This contains the Rubyripper codebase. It consists of five classes:
  • Gui_Support. This class handles all feedback communication with the user interface and is used a lot by the other classes (except Cddb). Also the log file and error analyzing takes place in here.
  • Cddb. This class handles the freedb fetching. It uses the Freedb class (dependent on ruby-freedb) to get info about the disc. The server contact is handled in the Cddb class itself. Some problems of the Freedb class made it impossible to rely on it. The biggest problem with using Freedb class is that it is using an old contact protocol and it almost always don't give any year info. So the Cddb class handles all server contact.
  • Secure_rip. As might be expected, all error correction logic is put in here.
  • Encode. As might be expected, this handles the encoding of the different formats supported.
  • Rubyripper. Handles the usage of the different classes. Also performs some logical checks before starting at all.
• rubyripper_cli.rb. It has one class that contains the code for the command line interface frontend.
• rubyripper_gtk.rb. It has one class that contains the code for the gtk2 user interface frontend.
• rubyripper.glade. This is a help file for the gtk interface. It's made with Glade, a program for designing user interfaces for gtk2.

Adding a new frontend

New frontends are encouraged and shouldn't be difficult to make. For instance, current gtk2 frontend is only 350 lines of code (+ the glade file, but this code is automatically created). As lead developer I only hope you will be consistent with the current gtk2 interface design. If there are good reasons to do it differently, please have a chat with me. As a start it would be best to use the current Gtk2 code and just plainly rewrite it for the other toolkit. The basic ideas should be more or less the same.