Producing DVDs on a Canopus Ultimate DVD Production Suite
by
Case Marsh, Marsh Video Productions
& Nathan Yanoff, Canopus Corporation
October 2001
The introduction of affordable DVD burners has made many desktop video producers anxious to try DVD production. Some see DVDs as the first significant development in desktop video production in a number of years. The good news for Canopus users is that your Ultimate DVD Production Suite is a great system to configure effective and easy-to-learn DVD production. Your foray into DVD production starts by installing the Hardware MPEG Encoder included in the Ultimate DVD Production Suite. DVDit LE for DVD authoring also comes included in your DVD Production Suite. The DVD Production Suite also includes a Panasonic LFD311 DVD-R drive, which is the last link in the chain. With these tools in place, you are able to perform the entire DVD production operation right up to burning a DVD itself, allowing you to successfully burn a complete one-hour video with an interactive menu on DVD-R media that will play magnificently in your home set-top DVD player.
The DVD production process starts by converting a completed RexEdit production on your hard drive into MPEG-2 elementary streams. There are various settings to optimize the output, most of which are nicely covered in the MPEG Encoder documentation. Of prime importance is consideration of the size of the output files. Current DVD-R media is limited to 4.7 GB. Setting the video parameters carefully and compressing the audio can produce excellent-quality DVD productions that are more than two hours long.
To make your settings, choose File > Create File From Timeline… > Create MPEG From Timeline… from the RexEdit menu bar. This opens a dialog box with multiple tabs. First, select the type of MPEG and stream type you want. From the other tabs, also specify the video details, audio details, filters, and output file targets. After all the parameters are set, you can start the conversion process. Canopus MPEG encoding is totally hands-off and extremely fast, proceeding at about 1.1x speed (i.e. a one minute clip will take one minute and six seconds to encode) using a single pass process that produces excellent results. The output files are slightly smaller in size than that of the compiled DVD files and are stored on your hard drive.
Authoring and compiling is the next step in the workflow. Details will vary depending on the software used. The DVD Production Suite includes DVDit LE, which is a mid-range authoring tool using a multiple window user interface. With DVDit LE, you can quite readily produce multiple title DVDs incorporating multiple movies and multi-level interactive menus. Compiling combines all the data files produced by MPEG2 conversion and authoring into directories and files that conform to the standard format for burning DVDs that will pay in set top players. DVDit LE writes directly to your Panasonic LFD311 drive or can write the files to a hard drive, using a hands-off process that proceeds at roughly 2x speed. With the Panasonic LFD311, burning is a hands-off operation at 1x speed for DVD-R.
Using your Canopus-based system, producers can produce excellent-quality DVDs. The quality rivals that of commercially produced DVDs, which are produced on two-layer media. Some additional skills and techniques are required, but a successful producer of VHS video should have no trouble learning what is needed to produce DVDs.
Long DVD Productions
Previously, we touched on the issue of setting the MPEG2 Encoder video and audio conversion parameters in order to produce the best video image quality for long DVD productions. The following discussion will go into more detail about the issues and the solutions available to desktop video DVD-R producers.
In a nutshell, the issue to be addressed is that 4.7 GB of available storage on a single layer DVD-R is not sufficient to produce high-quality results for long productions without carefully selecting the MPEG-2 video conversion settings and using audio compression. However, excellent results are possible by using the following guidelines.
The audio is the first thing you should consider, because the storage space on the DVD after the audio is laid down determines how much is available for the video. The Canopus MPEG Encoder will convert DV audio to uncompressed PCM (wav) or compressed MPEG Layer 2 audio. In addition, PCM audio can be converted to compressed AC-3 audio in a separate process. All three audio formats are high quality. PCM is universally compatible with set top DVD players, but is high bandwidth and thus not a good choice for long programs. Layer 2 is not compatible on many set top DVD players and may not be a good choice if you plan on wide distribution of your DVD. Compressed AC-3 audio sports low bandwidth and near universal compatibility on set top players, but is currently only available via relatively expensive conversion software. In any case, you need to carefully plan for the audio format.
The audio format you use determines the audio bitrate. PCM 16-bit stereo audio is 1,536 kbps. Layer 2 audio varies between 128 and 384 kbps. AC-3 audio varies too, but CD-quality stereo AC-3 audio is 192 kbps. Remember, the higher the audio bitrate, the more storage space that is used by audio and is unavailable for video. Set the audio parameters in the Audio Tab of the MPEG Encoder setup dialog. If you plan to use AC-3 audio, set the audio for 16-bit PCM and convert it to AC-3 in a secondary operation.
Once you have set the audio, proceed to the video. The Video Tab of the MPEG Encoder dialog has a number of settings. The default MP@ML profile, 720 x 480 resolution, variable bitrate (VBR), and default IBBP GOP pattern produces excellent results. Detailed information on what these mean is found in the MPEG Encoder documentation.
You also must select average and maximum video bitrates. This seems to be the source of most of the problems beginners have producing quality DVDs. Stated simply, higher video bitrates improve image quality, but higher video bitrates also fill up the available space on a DVD disc faster. The video bitrate becomes a very real issue for DVD production lengths over about 75 minutes long.
For programs up to 75 minutes long, there is plenty of room on a 4.7 GB DVD-R for uncompressed PCM audio and high-average-bitrate video. The Canopus MPEG Encoder defaults of 6 Mbps average and 6 Mbps maximum with uncompressed PCM audio work well. Increasing the maximum bitrate setting to 7.5 MB/sec does not affect the total video size (which is determined by the average bitrate), but it does, in theory, improve the quality of complex scenes somewhat with minimum impact to the quality of the simple scenes.
You will run out of available DVD disc space for programs over 75 minutes long using the above settings. Two strategies, used alone and/or together, can overcome these limitations. The first strategy is to reduce the audio bitrate to make more room for high-average-bitrate video. If you have AC-3 compression capability, or if you can use MPEG Layer 2 audio, you should compress the audio. However, compressing the audio can free up only so much space for video, and not everyone can compress or use compressed audio. Hence, the second strategy comes into play.
The second strategy is to reduce the average video bitrate. You can reduce the average video bitrate to about 4.5 Mbps without adversely impacting image quality. An average bitrate of 4.5 Mbps. will accommodate a program about 100 minutes long with uncompressed PCM audio. Lowering the average video bitrate to 3.5 Mbps, which still produces an image quality visibly better than SVHS, raises the capacity to about 118 minutes using PCM audio. Consider lowering the maximum bitrate somewhat as you lower the average bitrate. What you give up on the high end will be well used on the low end, and maintain consistently good quality throughout.
For long DVD productions, combining the two individual strategies is best. For a two-hour program of good quality, the dual strategy is absolutely necessary. The dual strategy starts by compressing the audio, followed by encoding the video at the highest bitrate that will not exceed the total available DVD disc capacity. The following formula calculates the video bitrate to use to fill up a DVD disc based on the selected audio bitrate.
Video Rate [in bps] = (598,566,666 / Time [in minutes]) - Audio Rate [in bps]
The formula is very simple to use and is universally applicable. For instance, for a 1 hour 50 minute production (110 minutes) in which 193 kbps. AC-3 audio is used:
Video Rate = 598,566,666/110 – 193,000 = 5,441,515 – 192,000 = 5,249,515 bps.
In this case, allowing about 5% headroom for authoring a simple title, a 5.0 average video bitrate would nearly fill the DVD. For the maximum bitrate, try 7.5 mbps, which is about 50% above the average bitrate setting and will produce good balanced results throughout the production.
As mentioned before, selecting the best audio in conjunction with optimal video bitrates are the two main strategies in producing long program DVDs. The secret is to make as much room as possible for the video by compressing the audio and then using all of the remaining available disc space for the video. The process is simple and straight forward and produces excellent results.
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