Whichever video capture hardware you’re going to use, the better the quality of the analogue video input the better the results you can expect to achieve. To this end it’s wise to weigh up if there are settings you can make on your VCR deck to optimise its playback quality.
Many modern-day VCRs have self-cleaning tape heads, which automatically remove tape particles and dust from the video heads. If your deck doesn’t, it’s advisable to clean its heads periodically, in accordance with the manufacturer’s instructions. Also, if your VCR has a sharpness control, turn it down. A softer image is likely to have less noise, which can benefit MPEG encoding. Some players also have a noise filter/edit control. Set this in a position to minimise sharpness and/or noise.
Its common for high-end capture cards and external converter boxes to support encoding to a number of different formats, typically MPEG-1, MPEG-2, MPEG-4 and DV. If this applies in your case, you’re going to need to to decide which of these formats you’re going to opt for before initiating the capture process.
MPEG-1 would only be an option if you wanted to produce a VideoCD (VCD) disc. If your DVD Player handles this format, this might be a viable option in situations where the source video footage was either too long to accommodate on a single DVD or of sufficiently poor quality for the inferior VCD format to make little discernible difference in the viewing experience.
There are a number of factors to consider when deciding which format to use to capture the video data::
- since DV is the less compressed format, it is a better archive format, which could be used at some future time, to produce a future generation, high density DVD disc
- capturing in DV format allows you to postpone any decisions concerning quality/size trade-offs that you may have the opportunity of making before the final MPEG-2 encoding of your footage, for DVD authoring.
- there was a time when reliable, precise editing was more easily performed in DV than in MPEG-2, but this is no longer the case with modern-day video editors.
On the other hand:
- converting straight to MPEG-2 or MPEG-4 has the advantage of significantly reducing the overall VHS-to-DVD conversion time and the amount of disk storage required
- it avoids the potential for the introduction of artefacts that interim DV encoding can sometimes cause.
The other important consideration is the quality of the encoder to be used. MPEG encoding is as much an art as a science, and while all encoders will comply with the DVD-Video standard the precise way in which they do so varies greatly, with each encoder applying a proprietary set of rules or algorithms, whether implemented in software or hardware.
If, for example, your external capture device has a well reputed MPEG encoder, you should use that whenever possible. If, on the other hand, your capture device can only produce DV output, you may want to do a bit of research into the relative merits of the many software encoders on the market before simply deciding to use the one that came with your bundled DVD authoring package.
MPEG-1 (aka White Book standard) was designed to get VHS-quality video to a fixed data rate of 1.5 Mbit/s so it could play from a regular CD using the VCD format. Published in 1993, the standard supports video coding at bit-rates up to about 1.5 Mbit/s and virtually transparent stereo audio quality at 192 Kbit/s, providing 352×240 resolution at 30 fps, with quality roughly equivalent to VHS videotape. The 352×240 resolution is typically scaled and interpolated:
- Scaling causes a blocky appearance when one pixel – scaled up – becomes four pixels of the same colour value.
- Interpolation blends adjacent pixels by interposing pixels with best-guess colour values.
Most graphics chips can scale the picture for full-screen playback, however software-only half-screen playback is a useful trade-off. MPEG-1 enables more than 70 minutes of good-quality video and audio to be stored on a single CD-ROM disc. Prior to the introduction of Pentium-based computers, MPEG-1 required dedicated hardware support. It is optimised for non-interlaced video signals.
During 1990, MPEG recognised the need for a second, related standard for coding video at higher data rates and in an interlaced format. The resulting MPEG-2 standard is capable of coding standard definition television at bit-rates from about 1.5 Mbit/s to some 15 Mbit/s. MPEG-2 also adds the option of multi-channel surround sound coding and is backwards compatible with MPEG-1. It is interesting to note that, for video signals coded at bitrates below about 3 Mbit/s, MPEG-1 may be more efficient than MPEG-2. MPEG-2 has a resolution of 704×480 at 30 fps – four times greater than MPEG-1 – and is optimised for the higher demands of broadcast and entertainment applications, such as digital satellite broadcast and DVD-Video. At a data rate of around 10 Mbit/s, the latter is capable of delivering near-broadcast-quality video with five-channel audio. Resolution is about twice that of a VHS videotape and the standard supports additional features such as scalability and the ability to place pictures within pictures.
In the late 1990s a new generation of entirely digital cameras and camcorders emerged, and with it a new video format, Digital Video (DV). It is an intraframe rather than progressive compression technique, using a three-stage process compress data – each frame being compressed on an individual basis rather than being compared to adjacent frames. The first stage uses DCT compression, a lossless technique which strips away information that cannot be seen by the human eye. It then separates the information from each pixel into brightness and colour and then samples this, favouring brightness over colour, which gives a colour representation that’s acceptable to the human eye but cuts down the data by a third. This is achieved by using YUV 4:2:2 encoding. The video then gets further reduced as the DV codec optimises the formula to YUV 4:2:0, bunching colour information from adjacent pixels in 4×4 blocks. Again, it’s a trade-off, but the human eye finds subtle variations in colour hard to detect, so in well-lit natural surroundings the difference is imperceptible. Finally, the hardware compression system on the camera compresses the video down further using an algorithm similar to M-JPEG.
MPEG-4 was introduced for high-definition video, and is primarily applied to HDTV and Blu-ray disk movie data. It can be applied to specialist DVD authoring for around 15 minutes of high-definition video, but it is not covered in this tutorial. The table below summarises the principal technical characteristics of the digital video formats discussed above:
|DVD Player compatibility||Very good||Good||None||Excellent|
|How CPU intensive||Low||High||High||Very High|
Much of the processing required to convert your video tapes to DVD is likely to push your PC to the limit, so it’s as well to spend a little time readying your system for the task ahead. The size of the data files involved is likely to be huge and the data transfer rates required need to be both high and sustainable over long periods of time. If you find there are problems with your PCs performance during digital video tasks there are a number of things that can be done to help ensure the hard disk subsystem performs optimally:
- try to locate the data files that will be used on a disk partition that is separate from the partition in which Windows and your applications reside
- make sure DMA (Direct Memory Access) is enabled for your hard disk drives
- try to avoid the hard disk drive where your .mpeg files will be located sharing the same channel as your DVD Writer
- ensure there is plenty of defragmented hard disk space available, and
- shut down all applications and processes you don’t absolutely need running before commencing each video cassette transfer.
- Transfer VHS to DVD Method
- VCR to DVD – Video Digitisation and Compression Codecs
- VCR to DVD Conversion – Video Capture Cards and PC Hardware
- How to Transfer VCR Video to DVD – Preparation
- Converting VCR Video to DVD Using Canopus ADVC-55
- Connecting External DV Converter Hardware to VCR and PC for VHS Video to DVD Transfer
- Testing the External DV Converter
- Installing the Software for the ADVC-55 DV Converter – including NERO
- One-Click Operation of VHS Video to DVD Transfer Using ADVC-55
- Rip / Import / Copy VCR VHS Video and Burn to DVD with Nero
- Labelling your DVDs – tutorial on how to transfer your VCR tapes to DVD