On the last page, we looked at building a Virtual CD from scratch using source files.  As most people with an optical disc burner already have a sophisticated software compilation suite, using Virtual CD with the suite allows one to create a Virtual CD the same as a physical disc and the ability to make use of the suite’s features such as creating boot discs, setting disc ISO parameters, etc.  This also allows the user to test and make changes to their compilations without the tedious process of physically burning a disc each time.  It would also come in handy for educational facilities, such as showing people how to write discs without the hassle and time spent dealing with physical discs and burners. 

Some applications that offer the ability to make backups (such as business sock control software) store their backups directly to a recordable disc.  By emulating a Virtual Burner, the application can make its backup to this instead and the Virtual CD can then be placed on a different medium such as an external hard drive, server, online storage, etc. as an alternative to an optical disc. 

Drive Information

To start with, let’s have a look at the Virtual Burner’s capabilities using Nero InfoTool:

As shown by the InfoTool, this drive features the writing support of all CD and DVD types apart from DVD+RW, DVD-R DL or Mount Rainier.  It also supports various advanced RAW writing modes.  However, it does not support the Blu-ray or HD DVD formats. 

Creating a Blank Medium

Like with a physical burner, it is necessary to prepare the Virtual Burner with a virtual blank medium before a burning application can write to it.  The simplest way to do this is to right-click the Virtual CD task tray icon, go into the Virtual Burner sub-menu, into “Create an insert a…” and select the type of blank medium to insert:

Specialised size discs can be created by choosing the option “Create and insert blank medium”.  This dialogue can also be accessed from the “File” menu option “Create a blank virtual medium” within the Virtual CD Management:

The medium size can be anywhere from 64MB to 17.5GB for DVD-R, DVD+R, DVD-RAM or DVD+R DL in steps of 64MB.  However, CD-R sizes are fixed at 601MB, 656MB and 703MB for the disc capacities 600MB, 650MB and 700MB respectively.  This dialogue also provides the ability to specify a description, a file location to save the disc image and whether to password protect and encrypt it.  One interesting thing we noticed is that there is no option in Virtual CD to create a blank CD-RW or DVD-RW medium despite the Nero InfoTool showing that this drive is capable of “writing” to such media.

Once a blank medium is loaded, the drive can be used as if it is a physical burner with an equivalent blank medium loaded.

Nero CD-DVD Speed & Writing Technique

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To start off with, we will carry out test writes of its virtual media formats to see how its performance compares with a physical burner.

CD Recordable (CD-R 700MB)

Going by the disc information, this virtual medium features a 78x write speed:

Let us test the creation of a data disc at its maximum speed using Nero CD-DVD speed’s “Create Disc” feature:

One thing that is very clear by this graph is that the Virtual Drive is not limited by the specified maximum write speed, since even if there was a 78x CLV CD burner, there is no way it could write a full 700MB disc in just 15 seconds!  The only thing that seems to limit its speed here is the time it takes to physically write the data to the hard disk.

DVD Recordable (DVD+R/DVD-R 4.7GB)

Going by the disc information, both the DVD+R and DVD-R virtual media feature a write speed of 8x.  The following is the disc information reported by Nero CD-DVD speed for the DVD+R:

The following is the disc information reported by Nero CD-DVD speed for the DVD-R:

Unfortunately when it came to creating a disc using Nero CD-DVD speed, it kept failing with a “No additional sense information” error for both the DVD+R and DVD-R Virtual media:

DVD Double Layer Recordable (DVD+R DL 8.5GB)

Going by the disc information, this virtual medium also features a write speed of 8x:

Unfortunately, like with the virtual DVD+R and DVD-R media, we also get a “No additional sense information” error when attempting to create a disc.

DVD-RAM (4.7GB)

The following is the disc information reported by Nero CD-DVD speed for the DVD-RAM:

One thing interesting to note is the unusual write speeds reported by CD-DVD speed.  For example, DVD-RAM typically comes in speeds of 2x, 3x, 5x and 12x, where as here we are reported unusual write speeds of 2.4x, 4x and 8x for this virtual medium.  However, once again, CD-DVD speed gave the same error when attempting to create a disc.

Nero Burning ROM 7

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With the widespread use of Nero and most burners being bundled with the Nero Essentials OEM version, we will create a few test discs with this suite.  To start off with, we chose the Virtual Burner as the Recorder:

We then carried out test recordings using the following virtual media:  600MB, 650MB, 700MB CD-R, 4.7GB DVD-R, 4.7GB DVD+R, 8.5GB DVD+R DL and a 4.7GB DVD-RAM.  We used a set of photographs as the source data to fill within 1MB of the virtual media capacity.  The results are as follows:

Unlike our experience with trying to create discs using Nero CD-DVD speed, Nero 7 was able to write to all the media formats successfully.  Like with the CD-R burn time we got earlier, all DVD formats wrote significantly faster than the selected ‘8x’ maximum write speed.  It appears that the only limiting factor is the physical time it takes to read the content from the source and write to the destination.  The times reported above are from the time we started the burn to the time Nero displayed the burn result.  These times varied significantly depending on the source files and the destination we specified for the Virtual CD, however, they are shown here to give a rough comparison of the different formats using the same source.

During the burn process of each media format, apart from DVD-RAM, Nero’s buffer went up & down repetitively throughout the write process.  The recorder’s buffer remained at a constant 4% throughout each burn process:

ImgBurn

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ImgBurn is a free but powerful disc image burning tool that supports the burning of a wide variety of disc image formats.  While at first it may seem unusual to use ImgBurn to burn a disc image to a Virtual CD that easily have been mounted directly to a virtual drive, it can come in handy when it comes to converting less common disc image formats that ImgBurn support, but are not supported in Virtual CD. 

To start with, we selected the destination drive in ImgBurn.  The following also shows the information displayed when a virtual blank DVD+R is loaded:

We wrote data to disc using photographs for the CD formats and the DVD+R DL format and a Debian DVD image file for the DVD-R, DVD+R and DVD-RAM formats.  The results are as follows:

Like with the Nero results, the Virtual burner appeared to accept data as fast as the source could provide and how fast it could store the virtually written data, with its own buffer going up & down every few seconds apart from the writing of the DVD-RAM format.  During the writing of all discs, the device buffer remained at 0%:

Cheetah Burner 2.2

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This is a clean, easy to use and inexpensive burning package recently reviewed on CDFreaks.  When we chose the Virtual burner and had any virtual DVD format loaded, we noticed that it gave a choice of ‘10x’ as a write speed:

We wrote to the same set of virtual disc formats as before using a similar set of source files.  The results are as follows:

Despite selecting the ‘10x’ write speed, the performance was no better than the ‘8x’ write speed with the other two burning software programs.  On the other hand, going by the writing times above, this still effectively writes much quicker than even the quickest 20x DVD burners. 

During the write process, Cheetah Burner just displays a basic dialogue showing the write process:

Virtual CD Editor

Virtual DVD-RAM tests