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Do-It-Yourself Primer
DVD is fast becoming the medium of choice for professionally
made videos. In order to make high quality DVDs you need the
high quality equipment. At HomeMovie.Com we assembled the
best encoding and authoring components required to create
Hollywood quality DVDs. From our professional DV and VHS decks,
Snell and Wilcox analog video converters with Noise Reduction,
SDI connections, Tascam audio converters, to the MPX3000 Hollywood
quality encoders. When you look at the amount of money and
time required to produce your own high quality DVDs with custom
graphics and chapters it just doesn’t make sense to try and
do it yourself.
Encoding the Video
One of the most important tools used to create DVD movies
is the MPEG2 encoder. The job of the encoder is to take the
video and audio from your master tape and put it onto a hard
disc as an MPEG2 video file and an Dolby AC3 audio file. These
files are then multiplexed together and combined with your
menus and graphics to create the VOB files that will become
your DVD when it is burned. There are basically two ways in
which this occurs: via Hardware or Software encoding.
Software Encoding
Software encoding actually requires a hardware step
first. This step involves moving the video from your master
tape to a hard disc via a Firewire connection or hardware
video capture card. The files created on your hard disc
are either AVI, Quicktime, or some brand of psuedo-MPEG2
(for video) along with a PCM type audio file. Unfortunately,
these files are not in the correct specification to use
for DVD and now must be transcoded from their existing format
to true, DVD compliant MPEG2 and Dolby AC3. Not only does
this require that up to twice the amount of hard disc space
be available, it also entails a lengthy process which can
be many times real time for both the video and audio. The
time effect of this process is substantial: for a two hour
movie, the best systems will require at minimum of 7 hours
of encoding, transcoding, and compiling and the average
systems make take 2 to 3 times that long. While software
encoding is substantially cheaper than hardware encoding
(as far as your initial investment), the amount of time
required to get ready to burn a disc is prohibitive.
Hardware Encoding
Hardware encoding is a much simpler process than software
encoding. The tape deck is plugged into a Hardware Encoder
Card that converts the video directly into a DVD compliant
MPEG2 file and the audio into a DVD compliant Dolby AC3
file on the hard disc. A 2 hour movie takes 2 hours to encode.
Hardware encoders cost more and tend to provide better results
over software encoders because they are specifically designed
to encode MPEG2 video where the software encoders are forced
to rely on the other components of your computer.
Noisy Video
Since a large portion of MPEG’s compression power depends
on its ability to locate areas of the image that do not
change between successive frames, noisy video can be a real
problem. While the actual video may be identical between
two frames, if there is a noise spot on one and not on the
other, it is detected as a change in video requiring more
bits to encode. Lots of noise causes poor encodes, with
the encoding resources being tied up trying to faithfully
reproduce the noise! Our Snell and Wilcox converters feature
special noise reducers, which help to eliminate the noise
in your video. With less noise your video will encode and
look better.
 At
HomeMovie.Com we use the same hardware MPEG2 encoder used
by Hollywood studios for their feature motion pictures. The
encoder provides real-time MPEG2 video encoding as well as
real-time Dolby Digital AC-3 audio encoding. Since both the
audio and video are encoded real-time into DVD compliant files
there is no need to transcode the files.
Professional Decks and SDI Connections
Digital Tapes
 Your
tapes are played through our professional VTRs. DV, DVCAM,
and DVCPRO tapes are played through Sony DSR-2000 decks.
The DSR-2000 allows us to encode DV tapes recorded in both
SP and LP modes. Many DVD Service companies can only playback
DV tapes recorded in SP. All of our DV decks are connected
directly to our MPX3000 encoders via SDI (Serial Digital
Interface) connections. SDI connections allow for higher
video quality compared to composite (RCA), S-Video (Y/C),
and even component connections.
Analog Tapes
 Your
analog VHS and S-VHS tapes are played through JVC BR-S500U
professional S-VHS decks. These decks have added Digital
Noise Reduction/Time Base Stabilization cards for superior
quality. The analog video signal is sent into a Snell and
Wilcox analog to digital converter. This converter also
features a noise reducer that we can adjust to filter the
video noise in your movie. Your new digital video is sent
back to the MPX3000 encoder via SDI.
AC-3 Audio: Is it that important?
Which is more important how your video sounds our
how your video looks? If you aren’t using AC-3 audio for
your DVDs you are sacrificing picture quality. Many low
priced encoders and DVD authoring packages use PCM audio,
which is uncompressed. AC-3 audio is compressed, but sounds
just as great as the uncompressed PCM audio. If your movie
is 2 hours long and you use PCM audio, the audio file
will take up 32% of the space on your DVD. AC-3 audio
would only take 4% of the available DVD space. The remaining
space left on the DVD is used for the video. Since PCM
audio uses more space on the DVD you will have to compress
the video at a lower bit-rate. Generally, the higher the
bit-rate is for the video the less compression is needed.
Less compression equals a higher quality video. |
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Limits of DVDIT, IDVD, and DVD Studio Pro
There are many DVD authoring applications that are marketed
towards the video professional. Each program will author a
DVD from your encoded audio and video files and then burn
the information to a DVD-R drive.
DVD Authoring Only
One of the main problems with DVDIT, IDVD and DVD Studio
Pro is that they only author the DVD for you. Each requires
at least one extra piece of encoding hardware or software
to capture the video into the computer. Then you still have
to have a DVD-R drive to make the actual DVDs.
Transcoding
None of these products will encode your video and audio
directly into DVD compliant files. In order to create DVD
compliant files your audio and video must be converted.
The process of converting one audio or video file type to
another is called transcoding. One of the problems with
transcoding video files into MPEG2 is that many transcoders
have the tendency to introduce motion artifacts and poor
video color into the transcoded file. If you have a 2-hour
movie, you first have to encode the audio and video into
your computer at real time, then transcode the audio and
video into DVD compliant files. Software transcoding can
be fast or slow, although many transcoders are optimized
for quality and not speed. For high quality encoders, it
can take up to 40 times the length of the source video for
transcoding to be completed. IDVD and DVD Studio Pro require
you to first create a QuickTime movie of your audio and
video. Once you have created the QuickTime file you have
to load a transcoding utility that converts the QuickTime
file into a MPEG2 video file and a PCM uncompressed audio
file. Then, if you want to use AC-3 audio instead of PCM
you have to run a different transcoding program that will
change the audio to AC-3. Sounds like a lot of work! At
HomeMovie.Com your audio and video files are encoded directly
into DVD compliant files. This gives you the best overall
quality and saves valuable time.
Fixed Bit-rate
Apples basic IDVD limits your videos to 1 hour. This is
because you can’t change the bit-rate for the MPEG2 transcoding.
It is fixed at it’s highest point. You would have to buy
DVD Studio Pro for an additional $1,000 for the ability
to change the transcoding bit-rate. DVDIT can transcode
your files into DVD compliant files at a fixed bit-rate
or you can import already encoded files. At HomeMovie.Com
we adjust the bit-rate depending on the length of your movie
for our premium products (Enhanced DVD or Director’s DVD).
This ensures that you will always get the highest bitrate
available.
Advanced Authoring Options
At HomeMovie.Com you can customize the playback of your
DVD any way you want. You can have your movie loop so it
is always playing or have a chapter loop back to the menu
for corporate videos. IDVD only lets you put in chapters
that loop back to the menu. You can't view your entire movie
unless you only have one chapter. No consumer DVD authoring
software gives you as many options as we do.
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