Creating DVD-Audio


About DVD-Audio Disc Creation

DVD-Audio (DVD-A) is a DVD disc format specifically targetting very high quality uncompressed music content. Standard music CDs (CD-DA) with a sample size of 16 bits and sampling frequency of 44.1 kHz provides high quality audio capability. While it is a subject of debate, higher sample sizes (24 bit) and higher sampling frequencies (48, 96 and 192 kHz) are generally believed to offer higher quality recordings with greater "detail" and higher dynamic range. DVD-A format provides this capability as well as offering greater storage size (4.7 GB for DVD vs 740 MB for CD). Information on DVD-A including the supported formats is available at Wikipedia.

The intent of this article is to describe one approach to creating DVD-A discs for musicians who wish to take advantage of the very high quality and versatile audio capabilities of DVD-A. A few important examples are:
It is also possible to store high quality 24bit/96kHz stereo audio files as DVD-Video format, or AC3 encoded surround sound tracks, but the audio format must be one type for all the audio tracks of DVD-Video. The advantage of archiving music as DVD-Video format is the ubiquity of DVD players supporting DVD-Video as compared to DVD players that support DVD-A format.

Professional DVD-A authoring software is expensive and the various choices are not discussed here (the capabilities of Steinberg's WaveLab6 for DVD-A creation will be discussed here in the future). Rather, this article will demonstrate the basic use of the free software dvda-author which is ongoing in development and not surprisingly does not contain the capabilities of professional authoring software, such as adding group, title and artist text labelling, not to mention still video image annotation. Nevertheless dvda-author provides the basic capability for creating DVD-A projects with the maximum number of groups and tracks and all the bit-depths and sampling frequencies are available. However dvda-author does not and will not support MLP (Meridian Lossless Packing) encoding which is required for 24bit/96 kHz 5.1 channel storage because uncompressed audio in this format would require a bit rate of 13.2 Megabit/sec. This is higher than then the maximum rate of 9.6 Megabit/sec supported by the DVD-A standard.
(Note that although the DVD-A format does not support LPCM 24bit/96 kHz 5.1 audio, most higher quality PC sound cards support direct playback of these 5.1 wav files, either as a single multichannel wav file or, with audio sequencers with multitrack mixing capabilities).

The photo below shows a simple home-made DVD-A disc along with the Creative Technologies DVD-A sampler demo disc packaged with the Creative Audigy 2ZS Notebook soundcard:



The Creative DVD-A Player version 2.00.78 display showing title, track and artist text labelling of the Creative DVD-A sampler demo disc:



Requirements

To create useful DVD-A content requires:
Audio Play Capacity with DVD

The amount of audio content in terms of play time depends on the bit size and sampling rate and number of channels of the audio content. The storage capacity of standard DVD discs is 4.7 GB (4,700,000,000 bytes) or 4,700,000,000/(1024*1024*1024) = 4.38 gigabytes. Some benchmarks for common audio sampling conditions are (with 1 MB == 1,000,000 bytes): Creating DVD-A Discs with dvda-author

All the examples below refer to the Windows version of dvda-author and the Windows XP platform. After recording your high-quality audio tracks, download the latest release version of dvda-author. Read the documentation carefully. You don't need to understand all the details of the DVD-A standard or the more advanced command-line options of dvda-author, but you should understand clearly any options you use (such as -f and -g). The first command, dvda-author.exe creates a 3 group file directory structure in the output folder DVD. That folder contains two sub-folders, AUDIO_TS and VIDEO_TS. With the command options below, the VIDEO_TS folder will be empty. The command imports all wav files found in each specified directory (wav1, wav2, wav3) into the corresponding groups. Each group should contain only one audio format (i.e. the same bit resolution and sampling rate and channel number) but different groups may contain different audio formats. The wav files are sorted in alphanumeric order. The mkisofs.exe command creates an iso image file of the DVD-A folder structure. The -sort option is required to ensure the iso file structure has the components in the correct order (see dvda-author docs for a simple example).
  dvda-author -f -o DVD -g wav1\*.wav  -g wav2\*.wav -g wav3\*.wav
  mkisofs -o image3g.iso -sort sort.txt  -udf DVD
The folder structure generated and the contents of the AUDIO_TS folder showing 3 groups are shown below:



A typical command-line ouput for the above commands shows the DVD-A structure generation details and typical "fixing" dialog.
It is a good idea to test the iso image of the DVD-A disk before burning to ensure that the order of tracks is correct and that all tracks play correctly, particularly if you were prompted for information for "fixing" (-f option) any track in the compilation. (Depending on how the wav files were recorded, dvda-author might consider the wav file headers to be corrupt in some way and will prompt you for verification of the suggested correction). Nero 7 has a utility called ImageDrive which makes it very easy to mount a disc image of the iso file for preview with any DVD-A player.

Playing a DVD-A Disc
After burning the DVD-A compilation iso image to disc, it can be played using hardware DVD players that support DVD-A or DVD-A software players. Higher-end Creative Technologies sound cards (X-Fi Elite Pro, Audigy 2ZS Platinum Pro, Audigy 2ZS Notebook etc.) come with the software MediaSource DVD-Audio Player which can play both basic DVD-A compilations (such as those created with dvda-author) and also commercial DVD-A discs with MLP and protection/copyright encoding. The image below shows the display of the Creative DVD-Audio Player for a DVD-A disc with 7 groups consisting of a total track count of 144 authored with dvda-author:



Nero 7 recognizes and can play DVD-A discs with up to 24bit/96 kHz stereo (without MLP) but not multichannel tracks (e.g. 24bit/48 kHz 5.1 LPCM):



The OEM version of PowerDVD which is included with some versions of Creative's X-Fi sound cards (currently version PowerDVD OEM 6CH) does not recognize DVD-A discs or images. However, the AOB files (Audio OBject) created with a DVD-A project can be opened and played with this version of PowerDVD. Interestingly, this version of PowerDVD DOES support playback (via the AOB file) of 5.1 wav files (as might be expected from the "6CH" product number):




References