Write Speed Tests

---

One thing that was clear from the above tests is that if the maximum write speed is specified, the Virtual Burner will accept data as quick as it can be supplied and in turn written to disk.  As we get a choice of various write speeds, we will now test to see if the lower speeds are enforced or if they are there for compatibility. 

The first thing we noticed when switching between Nero, Cheetah Burner and ImgBurn is that they all report totally different supported CD write speeds for the virtual burner!  The following table lists the available write speeds for each media type:

* - DVD-R, DVD+R, DVD-RAM, DVD+R DL

As the table shows, all three software packages gave very different available speeds to choose from for the CD-R format, with rather unusual speeds reported from both Cheetah Burner and ImgBurn.  All the DVD formats reported the same set of available speeds in each application and these at least were consistent between the applications.  Cheetah Burner interestingly gave an additional choice of 10x, which was available for all four DVD media formats.

Virtual CD-R Media

To see if choosing a write speed has any effect, we will test out all the available write speeds using a PCLinuxOS 2007 ISO with a 700MB virtual CD-R medium.  Before we start the tests for a given application, we carry out one write test to minimise the effect of disk cache between tests, since the first test will result in the full source ISO being read from disk, while subsequent tests will result in most or all of the ISO being read from the cache.  The results are as follows:

Nero Burning ROM

ImgBurn *1

Cheetah Burner *2

*1 - ImgBurn only gives a set choice of speeds ranging from 1x to 56x, so we chose the nearest speeds reported by the drive and added a 1x test just to see if this would have any effect.
*2 – Cheetah Burner does not give a choice of burners or write speeds for Burning ISOs, so for this test, we burned the ISO as a single file on a data disc.

One thing we found interesting with Nero Burning ROM is that it gives a noticeable write performance difference between write speeds.  Just to rule out the disc cache, the above results for Nero are on the second attempt, which gave pretty much the same times as the first attempt.  On the other hand, not even the fastest CD burner on the market today can burn 700MB to CD-R in just 1 minute 23 seconds, so it is obvious that these write speeds are not actually enforced and the Nero results are probably due to the way Nero supplies data to a burner for a given speed.  Both ImgBurn and Cheetah Burner appear to be unaffected by the chosen write speed.  Cheetah Burner’s longer write time appears to be the result of it maxing out the CPU throughout the burn process.

Virtual DVD Media

As we got a consistent choice of 2x, 2.4x, 4x and 8x for each of the formats DVD, this time we will carry out a similar test on each disc format using each software application.  As the source, we built a ISO file from photographs and used this same ISO for each test.  Like with the Virtual CD-R test, we carried out a non-timed pre-test to minimise the effect of disk cache on the timed tests.  The results are as follows:

Nero Burning ROM

ImgBurn

Cheetah Burner*

* - Cheetah Burner does not give a choice of burners or write speeds for Burning ISOs, so for this test, we burned the ISO as a single file on a data disc.

Like with the CD-R tests, Nero Burning ROM is the only application of the three where the specified write speed actually has a significant effect on the actual write speed.  Based on the time Nero took to write at 2x, it effectively wrote at 11MB/sec on average (assuming the lead in/out times are negligible), which works out at 8x.  However, while specifying a speed in Nero affects the actual write speed, it still does not reduce it to anywhere near that of any physical DVD burner.  We have received a note from H+H software stating that the write speed does not affected Virtual CD, which means that it is Nero that is having an effect here.  On the other hand, this would go unnoticed when using a physical writer, since it will only write at up to the specified speed.  As the tables of ImgBurn and Cheetah show, the specified write speed had no negligible effect on the actual write speed, confirming what H+H said. 

Content Write Tests

---

While we know that the Virtual Burner is well capable of handling data discs, in this test we will try creating other types of discs, including an Audio CD, CD Extra, Video CD, Super Video CD and a multi-session CD.  For these tests, we will use Nero Burning ROM and some wave audio files and video clips to create the audio & video discs from.

Audio CD

For our audio test, we used a set of wave files originally sourced from a pressed Audio CD and used Nero to write them with CD Text.  The compilation took around 25 seconds to write to our virtual CD-R medium.  When we mounted the Virtual CD, we were able to play it as if it was written to a physical disc:

However, despite us choosing to write CD Text to the disc in Nero, going by Exact Audio Copy, the disc contains no CD Text:

The song information Winamp retrieved above came from the online CDDB.

Mixed Mode CD

A Mixed Mode CD is a disc that contains a data session followed by a session of audio files.  For example, some music CDs include a data session to include music videos, screensavers, etc. that can be accessed when the disc is loaded on a PC.  For our test, we create a CD containing a handful of audio tracks and a data session containing some photographs.  Once the disc wrote, we mounted the disc and were able to browse its data files without any issue:

When we tried playing the disc in Winamp, we got loud static noise from the speakers.  As a Mixed Mode CD stores the data track as the first session, most CD players try playing the data track as if it is the first audio track and interestingly, despite using the latest version of Winamp, it will even try playing the data track as if is an audio track.  However, when we jumped to track 2, we started hearing the first audio track. 

CD Extra

A CD Extra disc is much like a mixed mode CD, with the exception that the audio tracks are written as the first session and the data track is written as a second session.  This has a huge advantage over the Mixed Mode CD format in that there is no longer a risk of CD players trying to play the data track as an audio track when the disc begins to play, as this is now at the end.  Like with the Mixed Mode CD, we picked out a handful of audio tracks and added some photographs to the data session. 

Unfortunately as the following result shows, it looks like this type of CD is not supported by the Virtual Burner:

We tried with and without CD Text, writing at 32x (which Nero chose by default) and at 78x, but each time it finished writing the audio session, it failed just as it started writing the data session.

Video CD

For the Video CD format, we took a few video clips from a digital camera and wrote them as a Video CD with a menu (letting Nero do the MPEG conversion) and also included some photos as some data files.  Once the disc wrote, we were able to play the disc as well as browse through the photographs stored on the disc:

Super Video CD

We prepared the Super Video CD format in the same way we did for the Video CD format.  Once the disc wrote, we also had no issue playing the disc and browsing through the photos written on the disc:

Multisession CD

A multisession CD is a disc that is capable of having multiple write sessions.  For example, one may store a set of files on a CD-R and then add another set of files to the CD-R at a later stage.  It is possible to keep adding sessions until the disc’s capacity has been exhausted, although each additional session uses up extra space due to an additional lead-in, lead-out and table of contents for each new session.

To start off with, we started a multi-session disc in Nero and wrote a handful of folders and files to our virtual CD-R medium.  The following browser window shows what we placed on the root of the disc:

Next, we went back into Nero and chose the option “Continue Multisession disc”, however, we were presented with the following message:

We tried again starting with a blank virtual CD-R medium trying the options “Track-at-once” and “Disc-at-once” and ensuring “Finalize disc” is not ticked each time, but we were still unable to carry out a “Continue Multisession disc” after the first session was written.  Finally, we tried once again using Cheetah burner, but when it came to writing a second session, we got the following message:

As a result, it looks like the Virtual Burner does not support the writing of additional sessions to a virtual CD-R.

Multisession DVD

Multisession DVDs work much like multisession CDs with the exception that multisession DVDs are not compatible with earlier versions of Windows than XP and certain DVD-ROM drives.  In this test, we use Nero to create a multisession DVD and then try adding a second session to it like we tried with the CD-R.

When we went to write to our first virtual medium, a DVD-R, we got the following warning about creating a multisession DVD-R:

We went ahead with the multisession disc and this created successfully.  However, when we remounted the disc image and tried adding another session, we got he same “This disc is not writable” message. 

We then continued trying writing two sessions through the different media formats with the following results:

After also failing with DVD+R and DVD+R DL, we got a surprise when it had no problem writing a 2^nd session to a virtual DVD-RAM medium.  We tried writing a 3^rd session to the virtual DVD-RAM, which also went successful, so it looks like this is the only virtual medium capable of handling the burning of multiple sessions.  Just in case it was a setting that had to be enable to allow multiple sessions on a virtual write-once medium, we tried the ISO versions of the virtual mediums and also looking throughout the program’s settings, properties for the virtual disc, virtual burner properties and so on, but without any success.

Virtual DVD-RAM tests

Smart Virtual CDs