The following pages provide technical data and work around solutions for encountered problems with submitted DVDs.

This information is quoted from media companies involved in the production of DVDs for submission to the BBFC. It is provided with the intention of reducing compatibility problems for anyone submitting work and will be updated as new errors and solutions are encountered.

Missing timing data on front panel display

A specific problem has occasionally been encountered where some DVDs have failed to display the counter on the front panel display of certain DVD players. This means that a runtime cannot easily be calculated, which is essential for classification – this data is used to efficiently schedule works for viewing, calculate the fee for submitting companies, to allow us to easily check for material differences between different versions of the same feature and to note where contentious moments may occur in a work.

Analyzing the VIDEO_TS.IFO of these discs using the freeware program IFO.EDIT has shown that the Video Manager Title Play Map contains the following characteristics:

• not one_sequential (random, shuffle, stills, loops, or more than one pgc)
• Jump/Link/Call commands invalid 0
• Prohibited user op. PTT play or search no
• Prohibited user op. Time play or search yes

This differs from discs which display timing data correctly and is due to the way the footage is organised on the disc.

Runtime data will not be shown where two or more video elements are stored within a single title, as shown above. The Program Chains (PGCs) contains runtime data for each video element.

As there is more than one PGC in the title folder, the DVD player cannot resolve an overall runtime for the title.

In order to correct this, separate out the video elements into separate title folders, as below so there is one Program Chain (PGC) per title folder.

 

Linking the separate video elements to a single PGC as shown will also correct this.

These screen shots are taken from Sonic Scenarist. Other authoring packages may implement this in slightly different ways, but the basic principal remains the same.

DVD fails to playback when .lay file is present in VIDEO_TS directory

Some DVDs have failed to playback when a .lay file is present in the VIDEO_TS directory.

This file appears to have been created by the software that was used to create the DVD and is often accompanied by a .layout file, although the .layout on its own does not appear to effect playback.

Removing the .lay file corrects the issue.

DVD playback errors

Recordable DVDs are less reliable than the replicated discs which are used for commercial DVD releases. Replicated discs are produced in a factory and the information is pressed onto the surface of the disc from a glass master copy.

In contrast, recordable discs use a dye which is burnt by a DVD burners laser to store the data on the discs surface.

This dye is less reflective than the surface of a replicated disc and results in less information being reflected from the surface of the disc. This leads to playback errors.

Playback failure rates

4989 works were submitted to the BBFC on DVD during a 12 month period from 31/01/2006 to 01/02/2007.

127 of these were rejected due to playback errors, 2.54% of works submitted on DVD.

13 DVDs were rejected because they did not display timing data as noted on page 3. That’s 0.26% of works submitted on DVD.

This shows an approximate compatibility rate of 97.2% which is in line with compatibility rates for DVDs quoted below.

For reference, the BBFC technical department carries out pre-viewing assessments of DVD submissions on Pioneer DVD-V7300D and V8000 DVD players. Submissions are examined and classified using Panasonic DVD-S29 DVD players.

For companies that have not submitted works to the BBFC before, we strongly urge you to submit test DVDs prior to submitting works for formal classification. This will allow us to overcome any technical difficulties which could delay the progress of works formally submitted for classification.

Reflectivity

Used with permission, courtesy of W. Timbers www.pinkpigeon.net/downloads

There are problems occasionally with DVD Recordables. The following is taken from the DVD Faq.

“The basic problem is that recordable discs have different reflectivity than pressed discs (the pre-recorded kind you buy in a store), and not all players have been correctly designed to read them”.

To reduce the problems of reflectivity and read errors

• Encode your video with an average bit rate below 6.5 Mbps
• If using VBR encoding, set the maximum bit rate to 9 Mbps or below
• Compress your audio to AC-3

Edge Effect

The edge effect describes the problem some DVD players have reading the information on the outer edge of the DVD. According to research undertaken jointly by the National Institute of Standards and Technology (NIST), the Optical Storage Technology Association (OSTA) and the DVD Association (DVDA):

• 38 out of 50 failures were in the outer edge of the disc
• “Edge” begins to appear around 10% from end of the disc and becomes significant around 5% from the end
• Ignoring errors outside the edge, compatibility rises to 98%

On a positive note the research noted that overall compatibility is improving over time.

To reduce the edge effect

• Avoid filling up the DVD with data right to the edge

Further steps you can take to safeguard against possible playback errors.

• Media quality matters – There exists significant variation in DVD Recordable media quality. Make sure you choose a good brand. “Manufacturers make modifications to the dye to improve its stability or to make it less expensive. This process may result in similar dye types having considerably different qualities.”
• Media-Burner combinations matter – When choosing DVD Recordable Media, make sure that it is recommended for your DVD burner. Often manufacturers provide this information on their websites. It is also important to keep the firmware on DVD burners updated.

Unstable Picture when down-converting from HD

This problem is only apparent when played back on an interlaced display. Progressive displays such as PC’s or HD screens will not display this problem.

This occurs when a 1440 x 1080i HD anamorphic edit is converted to m2v for Standard Definition DVD authoring.

Unlike other forms of interlaced video which run odd frames first, HD runs even fields first and this primarily caused the corruption.

The solution is to add an adaptive deinterlace filter at the input stage effecting the HD footage which is then served to the output deinterlaced and reinterlaced in the correct order of odd filed first for M2V.

The above information is quoted from media companies involved in the production of DVDs for submission to the BBFC. It is provided with the intention of reducing compatibility problems for anyone submitting work and will be updated as new errors and solutions are encountered.