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Video and DVD conversions
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Making DVDs (updated March
2003)
Herewith a big Tips page to pass on my
experience of making DVDs to order. You may indeed decide to buy the necessary
kit to make DVDs yourself (typically an MPEG capture card and Pioneer burner) -
good luck to you and I hope the following helps you out!
As a bare minimum, make sure your
PC runs Windows 98 or later, has an Intel processor of more than 700MHz, has
over 128MB of RAM and over 14GB of free hard disk space. Anything less and
you'll be struggling - I guarantee it! And this is all with an MPEG-2
hardware encoding card doing most of the 'work' - if you go down the DV route,
you'll need many tens of gigabytes free and tens of hours of computer
processor time to 'render' your video footage back into MPEG-2, ready for DVD.
And so to the tips, in approximate order of you
needing their content(!) They're categorised under Preparation - Capture - DVD
authoring - Testing - Final
thoughts
Preparation
- Despite what DVD-Rs say on their sleeve, you
only get 4.4GB of formatted capacity - this is your limit when working out what
footage and what bitrate to record. In fact, it's usually best to aim for about
4.2GB, to give yourself some margin for error - there's nothing worse, after 3
hours of computer processing, for things to grind to a halt because the DVD
image won't quite fit on the disc! Remember that your DVD authoring package is
usually only estimating the final file sizes involved.
- Clear hard disk space before starting (14GB
or so needed if your build approaches DVD-R's limit of 4.4GB) and
defragment.
- Do a clean boot so that Windows has as
little 'loaded' as possible, and then disable/close down all virus checkers,
firewalls, resource meters, PDA link utilities and the like. The less that's
running the better - trust me - you don't want to be dropping any frames or
running into problems due to the processor being too tied up with other
applications.
- Disable all screensavers and power-saving
options while recording or DVD burning. The last thing you want is a
screensaver to cut in or a hard disk to power down!
- If capturing from a video recorder,
double-check the tracking setting for the tape being captured - make sure
picture quality is optimised. And don't forget to wet-clean your video
recorder's playback heads regularly.
Capture
Capture from your capture card in MPEG2, at 2 to 8Mbits/s,
depending on quality needed, action in the clip and space available/capacity
required. 2Mbits/s - OK for stuff with little going on, pixellates horribly
when something happens or when using low quality original footage. 4Mbits/s -
good results, pixellation effects not obvious, but blurring on fast action.
6Mbit/s - excellent, almost perfect. 'Proper' commercial DVDs tend to use
8Mbits/s and upwards. Note the tradeoff in disk capacity - at 8Mbit/s, you'll
only fit just over an hour's worth on each DVD-R. Note also the 'bandwidth'
requirements inside your computer at higher bit rates - at 6Mbit/s, your hard
disk is having to receive and store almost a Megabyte every second - this
doesn't sound too bad, but consider that it has to keep up, with no
glitches or slight interruptions whatsoever throughout a long
presentation.
- If capturing (perhaps from camcorder) into
MPEG files that will be edited/stitched later on and re-encoded into a more
polished whole, make sure to use as high a bit rate as possible at the capture
stage. You can always drop the bit rate for the final burnable MPEG files, but
you can't up it. And re-encoding low bit rate files at a similar low bit rate
produces horrible flickering and other artefacts...
- Check the audio side of your video source
before capture. If it's stereo, then make sure you use a stereo VCR and check
the capture card/software recognises the feed as stereo as well. Obviously,
this is especially important for music clips. Don't forget to set the audio
levels properly - it's very easy to overlook this step and end up with a
perfect video picture and a distorted or over-quiet soundtrack!
- Remember to use the same pixel resolution
for all clips on the DVD. Note that a video resolution of 704 by 576 is OK.
Leave at that resolution if forced to by your capture card, despite the more
usual DVD requirement for 720 by 576.
- Disable on-screen preview while recording
(if possible), using timings and presets and audio to end the recording.
Running a preview is often a fairly processor-intensive task and will increase
the risk of dropped frames and glitches in the megabyte per second stream of
data that you're trying to write to your hard disk.
- If there are serious glitches in the source
video (e.g. where a camcorder has been stopped and then restarted, or between
TV programmes), you may find that these translate to synchronization issues in
the final, DVD-authored VOB files. Where you know about dropouts and glitches,
factor them into your captures by doing several short captures rather than one
long one.
- Remember to sample some audio/pictures as
you go, for use in the DVD menus.
- Remember that any separate audio clips need
to be sampled at 48kHz, not the 44kHz (CD) standard.
DVD
authoring
- For authoring DVDs, steer clear of the
budget Sonic MyDVD (a.k.a.DVDit!) software - it's VERY picky about MPEG streams
and formats and is fond of crashing two hours into a build with something
helpful, such as 'Unknown error -1'. In addition, it insists on using
uncompressed audio on the final disc, meaning you can fit 30% or so less video
footage per disc. Much more robust, powerful and efficient (if a lot less
freeform) is Ulead's DVDMovieFactory. Even better if you can afford it is
Ulead's DVD Workshop, with which I've had very good results when using good
quality captured video streams.
- When authoring your DVD (and only if your
authoring package gives you a choice) don't use buttons/text near the screen
edges, they won't be seen on a TV, which cuts off around 10% all round from the
full computer video image. Luckily, this also means it cuts off the irritating
'head switching noise', often seen flickering away at the bottom of video
footage. Use dark buttons/text wherever possible, so that DVD player
highlighting doesn't confuse the user with white buttons glowing white, etc.
8-)
- Don't forget to put in 'Back' or 'Home'
buttons, where applicable - never force the user to eject the DVD and reinsert
it just to get back to the title menu!
- Remember to allow plenty of computer time
for the conversion process. Even after all your material is assembled, it will
still take at least 3 hours of computer processor/hard disk time
to encode (on a Celeron 700MHz PC), image-write and burn two hours of footage
onto a DVD-R.
- It's generally OK to buy low-cost (£1
a disc now, from 121cdr) 'general'
DVD-Rs - you don't need to worry about 'authoring' discs, which are designed
for adding region encoding and protection systems. Go for the cheapest branded
media - the very cheap unbranded ones often have problems on their outer edges.
No need to pay top dollar though - aim for about £1 a Disc.
- Be prepared to split longer (over 1 hour)
movies into smaller chunks if appropriate or necessary. This has two benefits:
(i) any audio synch errors that have been creeping in (heaven forbid) won't
carry forward into the next section (ii) if one segment has a problem or glitch
(for whatever reason), you only have to capture that section again rather than
the whole thing. Although the movies will appear separately on the DVD menu,
you can set them to automatically follow each other - all the viewer will
notice is a pause of a second or so.
- Before burning to a DVD-R disc, blow on it
gently to remove dust and also clean it radially (if necessary) with an
appropriate disc-wipe.
Testing
- Encode test VOBs check them thoroughly on
the computer first. Although you may not e able to view a DVD's navigation
features using just the raw VOB file(s), you can at least skip through to their
end (in WinDVD or PowerDVD), to check smoothness and that audio/video
synchronization is maintained properly.
- If you spot problems in the encoded footage
at any stage, double-check the problem isn't the playback means instead of in
the MPEG encoding itself. Many is the time I've thought my capture system at
fault when it turned out to be problems with the playback software and
hardware.
If you do spot a problem, double-check that it also shows up when
the footage is played using a different DVD application/viewer before assuming
the worst. In particular steer clear of Microsoft Media Player, which often
shows up video streams as far worse than they really are...
Final
thoughts
- For optimum compatibility with both computer
DVD drives and set top players, make sure you use your DVD authoring software
to do the disc-writing. Tempting though it is to burn your test VOBs and folder
straight onto a DVD-R with generic CD/DVD data writing software, the DVD
specification is quite particular about the order and placement of files and
folders and discs burnt by hand seem to play on fewer players than those burnt
by authoring software such as DVD Workshop.
- Make sure you keep your
capture/authoring/burning software patched right up to date - check the
developer web sites for updates. The DVD authoring world is still maturing and
important compatibility fixes are being rolled in regularly.
Never throw away your source material
(VHS/camcorder/AVIs/whatever), or even your captured MPG files - no matter how
well you make a DVD, there will always be something that you think could
be done better when you have the time. And one day you will...
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