Note: Descriptions are shown in the official language in which they were submitted.
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
METHOD, SYSTEM, AND PROGRAM PRODUCT FOR
ELIMINATING ERROR CONTRIBUTION FROM
PRODUCTION SWITCHERS WITH INTERNAL DUES
Background Of Invention
Field of the Invention
The invention relates to the creation, manipulation, transmission, storage,
and especially
synchronization of mufti-media entertainment, educational and other
programming
having at least video and associated information. The invention will find
particular use
with respect to the creation and distribution of television programs.
Background Art
The creation, manipulation, transmission, storage, etc. of mufti-media
content, be it
entertainment, educational, scientific, business, and other programming having
at least
video and associated information requires synchronization. Typical examples of
such
programming are television and movie programs, motion medical images, and
various
engineering and scientific content. These are collectively referred ~to as
"programs."
Often these programs include a visual or video portion, an audible or audio
portion, and
may also include one or more various data type portions. Typical data type
portions
include closed captioning, narrative descriptions for the blind, additional
program
information data such as web sites and further information directives and
various
metadata included in compressed (such as for example MPEG and JPEG) systems.
-1-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
Often the video and associated signal programs are produced, operated on,
stored or
conveyed in a manner such that the synchronization of various ones of the
aforementioned audio, video and/or data is affected. Fox example the
synchronization of
audio and video, commonly known as lip sync, may be askew when the program is
produced. If the program is produced with correct Iip sync, that timing may be
upset by
subsequent operations, for example such as processing, storing or transmission
of the
program.
One aspect of mufti-media programming is maintaining audio and video
synchronization
in audio-visual presentations, such as television programs, for example to
prevent
annoyances to the viewers, to facilitate further operations with the program
or to facilitate
analysis of the program.
The video and audio signals in a television system are increasingly being
subjected to
more and more steps of digital processing. Each step has the potential to add
a different
amount of delay to the video and audio, thereby introducing a lip sync error.
Incorrect lip
sync is a major concern to newscasters, advertisers, politicians and others
who are trying
to convey a sense of trust, accuracy and sincerity to their audience. Studies
have
demonstrated that when lip sync errors are present, viewers perceive a message
as less
interesting, more unpleasant, Iess influential and less successful than the
same message
with proper lip sync.
Because light travels faster than sound, we are used to seeing events before
we hear them
- lightning before thunder, a puff of smoke before a cannon shot and so on.
Therefore, to
some extent, we can tolerate "late" audio. Unfortunately, as shown in Figure
1, even in a
simple television system, the video is almost always delayed more than the
audio,
creating the unnatural situation of "early" audio. Any one contributor to the
lip sync error
may or may~not be noticeable. But the cumulative error from the original
acquisition
-2-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
point to the viewer can easily become both noticeable and objectionable. The
potential
for lip sync errors increases even further when MPEG compressed links are
added to one
or more stages of the overall system
As shown in a typical television Figure 1, as video moves from video pickup
devices,
typically CCD cameras, 101 and 111, to frame synchronizers, 103, production
switchers,
121, digital video effects, 121 and 131, noise reducers and intermediate
transmitters, 135,
and receivers, 141, including MPEG encoders and decoders, more frame
syncronizers
143, local transmitters, 151, tuners and demodulators, 161, and TVs with
digital
processing, 171 and the lilte, and as the audio goes from remote and studio
pickup, 101
and 111, to an audio board, 123, further audio processing, 133, intermediate
transmitters,
135, and receivers, 141, through audio limners, 145, and local transmitters,
151, to a
tuner-demodulator, 161 and an audio amplifier and speaker, 173, the video is
delayed
more than the audio. The cumulative delay of the video with respect to the
audio can be 6
or more frames. With the inclusion of video and audio compression in any
parts) of the
system the video delays with respect to audio can be much more. Worse yet, the
amount
of video delay frequently jumps by a frame or more as the operating mode
changes, or as
frames of video are dropped or repeated to achieve synchronization of the
video to studio
and other references. Using a fixed audio delay to "mop up" the audio to video
timing
errors is rarely a satisfactory solution because of the constantly changing
video delay.
While not shown in this typical system of Figure 1, data is frequently carried
along with
the video signals through much of the system, via separate paths, thus when
the video is
delayed as described above, the timing of the data relative to the video is
disrupted. Using
a fixed data delay to "mop up" the data to video timing errors is rarely a
satisfactory
solution because of the constantly changing video delay
Standards committees in various countries have studied the lip sync problem
and have set
-3-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
guidelines fox the maximum allowable errors. For the most part, these studies
have
determined that lip sync errors become noticeable to most viewers if the audio
is early by
more than 25-35 milliseconds (about 1 NTSC frame) or late by more than 80-90
milliseconds (2.5 - 3.0 NTSC frames). In June of 2003, the Advanced Television
Systems Committee (ATSC) issued a finding that stated "... at the inputs to
the DTV
encoding device...the sound program should never lead the video program by
more than
15 milliseconds, and should never lag the video program by more than 45
milliseconds."
The finding continued "Pending [a finding on tolerances fox system design,
designers
should strive for zero differential offset throughout the system." In other
words, it is
important to eliminate or minimize the errors at each stage where they occur,
instead of
allowing them to accumulate.
Fortunately, the "worst case" condition in Figure 1 is now less lileely to
present itself than
was the case a few years ago. Firstly, it is now quite common to install audio
traclung
delays, exemplified by the Pixel Instruments AD-3000 or AD-3100, alongside
each video
frame synchronizer or other video delay devices having delay signal outputs,
thereby
eliminating at least one common source of.variable lip sync errors.The AD-3000
and AD-
3100 variable audio delays are available from Pixel Instruments Corp. of Los
Gatos, CA.
Secondly, due to the continuing cost effectiveness of digital electronics,
newer master
control switchers have an internal DVE for squeezebaclc operation rather than
an external
DVE. This allows the use of a constant insertion delay of 1 frame for both the
video and
the audio paths in all modes of operation.
Unfo1-tunately, again due to the continuing cost effectiveness of digital
electronics, newer
master control switchers are now incorporating built in video frame
synchronizers, scan
converters and other video delaying circuitry.
-4-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
Since the 1970s, digital video effects processors (DVEs or transform engines)
have been
used to produce "over the shoulder", "double box" and other multiple source
composited
effects. The video being transformed is delayed (usually by one or more
frames) relative
to the background video in the switcher. So, any time one or more DVE
processors are
on-air, the associated video sources will be delayed, resulting in a lip sync
error. In the
past, when the DVE processor was external to the switcher, a tally signal from
the
switcher could be used to trigger the insertion of a compensating audio delay
when the
DVE in on-air. However, today's production switchers are usually equipped with
internal
DVEs and a tally output is no longer available.
Thus, a need exists for a method, system, and program product for producing
time
synchronized multi-media signals.
Summary of the Invention
The present invention provides for method of producing time synchronized mufti-
media
signals.
The preferred embodiment of the present invention is a method, apparatus
(system), and
program product where audio and video portions of mufti-media content, e.g., a
television
or other program, may be synchronized by inserting arid controlling
appropriate audio
delays. This increases the apparent synchrony of the desired signals.
The method, system, and program product described herein provide for entering
a delay
value in the relative timing of a video signal conveying a plurality of images
and an
associated signal, as an audio signal. This is accomplished by a method,
system and
program product for producing time synchronized mufti-media signals. This is
done by
inputting a start pulse, for example, a GPI Start pulse, a stop pulse, for
example, a GPI
-5-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
Stop pulse, and a tally line for each video input. The next step is generating
a Timer
On/Off signal and a Time Value signal for each set of start pulses, stop pulse
and tallies,
and providing the Timer On/Off signal and a Time Value signals to a muter.
These
outputs are properly associated with each other, processed and coupled to an
audio
synchronizer as one or more control signals, which in the preferred embodiment
are a
single signal of delay steering pulses for control of the delay of the audio
signal.
One feature of the present invention is that the number of Interfaces and
Tally contact
closures can be stored in the timelines to control external devices. In other
words, by use
of the muter, various combinations of input signals (tallies & GPIs) can be
associated
with the delay setting to create delay output signals. Since the video delay
through the
switcher is usually predictable (based on the combination of effects), an
external,interface
can be used to interpret the GPI and tally outputs and generate the necessary
steering
commands to control audio synchronizers. This permits automatic correction of
the lip
sync errors. For example, the DG-1200 interface from Pixel Instruments can be
preset to
provide up to twelve different delays and can steer up to five audio
synchronizers.
Depending on the application, the insertion of the audio delay can be
triggered by tally
signals, GPIs, or a combination of both. Gating the tally signal with GPIs
improves the
immunity to false delay insertion.
For example, by way of illustration of the capabilities of the preferred
embodiment of the
invention, consider a simple video switcher system having two DVEs. The first
DVE has
a variable delay of 0-1.5 frames~and the second DVE has a fixed delay of 2.25
frames.
DVE 1 has a corresponding pair of GPI signals and a tally signal. DVE 2 has
only an
associated tally signal. For DVE 1 the GPI signals will indicate the current
delay, that is
the GPI start is triggered when a particular video frame enters DVE 1 and the
GPI stop is
triggered when that same particular video frame exits DVE1. The associated
tally is
asserted when the output of DVE1 is being utilized by the switcher. When the
output of
-6-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
DVE 2 is being utilized by the switcher its associated tally is asserted. The
DG-1200 will
(as set up by an operator) receive the two tallys and two GPI signals as well
as a 2.25
frame delay value. These signals and the delay value are utilized to create a
delay output
signal (DDO pulse) to control an audio synchronizer to cause the audio
synchronizer
delay to match the video delay of the production switcher as the two DVEs are
inserted
into (and taleen out of) the video path. The two GPIs corresponding to DVE 1
are utilized
to determine the current DVE 1 delay. The two tallies are used to determine if
one or both
DVEs are inserted into the video path. If DVE 1 is inserted (as determined by
its
corresponding tally), its delay (as determined by the GPIs) is added to the
DDO signal. If
DVE 2 is inserted (as determined by its corresponding tally) the 2.25 frame
delay value is
inserted into the DDO signal. Consequently the DDO rnay indicate 0 delay
(neither DVE
is used), the DVE 1 delay (DVE 1 is in use), a 2.25 freme delay (DVE 2 is in
use) or a
delay of 2.25 frames plus the DVE 1 delay (both DVEs are in use).
The preferred embodiment of the invention has the ability to utilize and
configure its
various inputs to match differing video systems. As just one of many possible
examples,
the GPIs may be utilized as an indicator of when a DVE is being used (as
compared to
indicating a varying delay as in the above example), or as an additional
indicator along
with the tally.
The Figures
Figure 1 illustrates a typical train of prior art processes and units to go
from a multi-
media piclcup, through pre-transmission level processing, transmission,
receiving, and
receiver level processing (including tuning and demodulation) to final
presentation to an
end user or viewer.
Figure 2 shows a system for using General Program Interfaces and Tallies,
through a
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
control router, to timers, to generate delay steering pulses to an audio
synchronizer.
Figure 3 illustrates a system for receiving video inputs through a video
switcher with
internal DVE's to generate GPI's and Tally signals, to an interface with a
plurality of
audio delays which system includes an embodiment of the present invention
operable to
generate delay steering pulses to an audio mixer, where the audio mixer
provides a
corrected audio output. Note that while Figure 3 illustrates a typical system
by way of
example, one of ordinary skill will recognize that the teachings herein are
applicable to
general systems, methods and products wherein video signal processing causes
changing
video delays.
Figure 4 illustrates video inputs and audio inputs with a video switcher with
internal
DVE's to generate GPI's and Tally signals, which system includes an embodiment
of the
present invention operable to generate a delay steering pulse to control a
single audio
delay operating on audio out of an audio mixer to provide a corrected audio
output. Note
that while Figure 4 illustrates another typical system by way of example, one
of ordinary
skill will recognize that the teachings herein are applicable to general
systems, methods
and products wherein video signal processing causes changing video delays.
Figure 5 illustrates a schematic diagram of the preferred embodiment of the
present
invention having an interface to interpret the GPI and tally outputs and
generate the
necessary steering commands (preferred to be DDO signals) to control one or
more audio
synchronizers to permit automatic correction of timing and synchronization
errors, such
as lip sync errors.
Detailed Description of the Inveintion
_g_
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
The preferred embodiment of the invention produces time synchronized mufti-
media
signals. This is done as one example by inputting a start pulse, for example,
a GPI Start
pulse, a stop pulse, for example, a GPI Stop pulse, and a tally line for each
video input.
The next step is for example generating a Timer On/Off signal andlor a Time
Value
signal for each set of start pulses, stop pulse and/or tallies, and providing
the Timer
OnlOff signal and a Time Value signals to a muter. The information conveyed by
these
signals are routed to an audio synchronizer as delay steering pulses for the
audio signal.
The number of GPI and Tally assertions (typically contact closures) can be
stored in these
timelines to indicate system configuration and/or control external devices.
Since the
video delay through the switcher (or other system) is usually predictable
(based on the
combination of effects), an external interface of the present invention can be
used to
interpret these GPI and tally outputs and generate the necessary steering
commands to
control audio synchronizers. This permits automatic correction of the lip sync
errors. An
interface, such as the DG-1200 interface from Pixel Instruments can be preset
to provide
up to twelve different delays control signals (DDOs) and can steer up to five
audio
synchronizers. Depending on the application, the control of the audio delay
can be
triggered by tally signals, GPIs, or a combination of both. By utilizing the
Control Router
531 which recognizes and couples desired ones of GPI and Tally input signals
(for
example via 511 and 521), Delay Time Values (for example 513 and 523) to the
desired
timers) (for example 541 and 551) one or more Delay Steering Signal may be
generated
to respond to the video system and reflect the current video delay of that
system. Gating
the tally signal with GPIs can be utilized to improve the immunity to false
delay insertion.
Multiple signals may be utilized in sequence or in tandem to improve
reliability or to
allow operation with simple or complex video systems.
Figure 2 illustrates by way of example one preferred embodiment system where
GPI start
-9-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
signals, Tally signals, and GPI stop signals are input.to tally latches 211-
221. The
outputs of the Tally Latches, a timer on/off signals and time values, are
input to a control
muter 231. Additionally, Delay Time values 213 - 223 are input to the control
routes. The
control routes 231 outputs desired ones of the OnlOff and Time signals to
individual
timers 241 - 251, which in turn generate delay steering pulses which are
suitably coupled
to one or more audio synchronizers. The Tally Latch may be configured to
respond to the
input GPI Start, GPI Stop and Tally signals in various ways. It is preferred
that the
outputs of the Tally Latch may be configured (by operator or manufacture) to
represent all
of the possible Boolean and/or digital logic operations of the three input
signals, however
lesser numbers of the possible Boolean and/or digital logic operations may be
utilized as
desired, Of particular interest are two combinations of digital logic and
Boolean operation
which will be described below.
The first combination of particular interest provides selectable inversion of
each input, a
selection of edge trigger or level trigger for the GPI inputs to control a
set/reset flip flop
function. The output of the set/reset function is anded by the tally signal
and the output
selectably .inverted. This capability allows any input and output polarity. A
delay time is
established by setting the set/reset function with the GPI start (by edge or
level trigger)
and resetting with the GPI stop (by edge or level trigger). The resulting time
duration
(pulse) is counted to provide the established delay time which is coupled to
the Control
Routes. In addition the set/reset pulse from the set/reset function itself is
anded with the
tally and the output coupled (in either polarity) to the Control Routes. The
Tally is
coupled to the Control Routes. In this fashion the inputs to the Control
Routes are 1) the
Tally, 2) a pulse corresponding to the delay between GPI start and stop, 3)
that pulse
anded by the Tally. In addition a seperate Delay Time Value established by
manufacture
or the operator is input to the Control Routes. The Control Routes may then
couple
various desired ones of its inputs to the desired timer to generate Delay
Steering Signals
(DDO Pulses). This combination is useful to measure a changing delay as
provided by the
-10-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
timing of the GPI start and stop and the Tally is used to indicate when that
changing delay
is inserted in the video signal path. The changing delay can also be
associated with the
Delay Time Value from 213 - 223, for example added to it. This is useful for
systems
which have a fixed minimum delay to which a variable delay is added.
A second combination of interest provides a selection of edge trigger or level
trigger for
the GPI inputs to control a set/reset flip flop function. The output of the
set/reset function
is anded by the tally signal and the output selectably inverted. This
capability allows any
input and output polarity. The set/reset level from the set/reset function is
anded with the
tally and the output coupled (in either polarity) to the Control Router. In
addition a
seperate Delay Time Value established by manufacture or the operator is input
to the
Control Router. The Control Router may then couple various desired ones of its
inputs to
the desired timer to generate Delay Steering Signals (DDO Pulses). This
combination is
useful for systems where GPI start and stop are used in addition to the Tally
to indicate
when a fixed delay is inserted in the video signal path.
The preferred embodiment ability to configure the Tally Latch, as well as the
Control
Router and Timers at taught herein is easily provided by configurable
or.programmable
logic ICs, such as those manufactured by Altera and Xilinx, and operating
under control
of a suitable microprocessor, as is well known to those of ordinary shill in
the art.
The aforementioned preferred embodiment of the second combination is available
commercially in the previously mentioned DG-1200 which was introduced.at the
2004
National Association of Broadcasters convention held April 17-22, 2004 in Las
Vegas,
Nevada. The DG-1200 is available from Pixel Instruments Corporation of Los
Gatos, CA.
As shown in Figure 2 each of the twelve input channels consists of a GPI Start
pulse, a
-11-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
GPI Stop pulse, 211 and 221, and a Tally line, 213 and 223. Each input channel
also has
a linked delay time register with a user selectable value from 20 ,sec
(nominally zero
delay) up to 6.5 seconds, in increments of 100 ,sec. Delay times can be
entered and
displayed in milliseconds or in TV fields (NTSC or PAL). ~ther configurations
and
values may be utilized as desired.
Any input channel and its time value (from either or both the Delay Time Value
and the
GPI determined delay time value) can be routed through a control router 231 to
any of the
output timers 241 and 251 and each timer can steer a separate audio
synchronizer, as an
AD-3100 Audio Synchronizer. The output timers, 241 and 251, can have different
time
values and can be turned on and off independently in response to the
respective input
signals. Also, any timer can be controlled by more than one input channel.
Assume that
one switcher effect needs a one frame audio delay and another effect needs a
two frame
audio delay. Input #1 (or any other input) can enable a 1 frame delay in Timer
#3 (or any
other timer) and the associated audio synchronizer, as an AD-3100. Any other
input can
be used to enable a 2 frame delay in the same timer.
Pre-Delayed Audio Application
The most comprehensive solution is to add an audio synchronizer, as an AD-3100
Audio
Synchronizers, ahead of the audio mixer 315 as shown in Figure 3. This
configuration of
a video switcher with internal DVE's 301 generating GPI and tally signals,
with the GPI
and Tally signals as input to an interface 303 thereby generating delay
steering pulses to
audio delays 311 and 313, and the audio mixer 315. This provides a corrected
audio
output. This ensures that all sources contributing to the program output have
the correct
lip sync.
For applications that require more than 5 audio inputs to be delayed, this
solution is
-12-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
scaleable with additional DG-1200s and AD-3100x.
Post-Delayed Audio Application
A simpler, but less comprehensive solution is shown in Figure 4, where a
single audio
synchronizer, as an AD-3100 Audio Synchronizer is added at the output of the
Audio
Mixer. The amount of delay added to the audio path is chosen as a compromise
for the
various sources contributing to the program output in any given effect.
As shown in Figure 4video inputs are input to a video switcher with internal
DVE's 411.
This provides GPI and Tally signals output as input to an interface 421, which
produces
the audio delay steering pulses. The video switcher 411 also produces program
video out
with video through DVE paths delayed when a DVE is on the air. The output of
the
interface 421 is input to an audio delay 431, where, along with audio inputs
441 through
an audio mixer 443 the delay steering pulse correction is applied to yield a
corrected
audio output 453.
For example, in a typical newscast over the shoulder shot, the studio anchor
has zero
video delay and the remote reporter (in the box) has one frame of video delay.
Setting the
audio synchronizer, for example, an AD-3100 Audio Synchronizer, delay to
between 0
and 0.5 frame is the best compromise for both sources. The studio anchor's
audio will be
slightly late and the remote reporter's audio slightly early. The residual lip
sync errors are
reduced compared to doing nothing at all.
Rapid Delay Change With Pitch Correction
Since the video delay of the DVE may be switched in and out of the program
path several
times in a relatively short period, it is essential that the audio delay
"catch up" quicldy.
Conventional audio synchronizers typically change their delay at a rate of
0.5% or less.
-13-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
This means that for each 1 frame increase or decrease in the video delay, the
audio does not
"catch up" for 10 seconds or more. In systems where the video delay changes at
the start of
a 15 second commercial, this would cause most or all of the commercial to
suffer lip sync
errors.
In a preferred exemplification, the audio synchronizer, as an AD-3100,
incorporates
automatic pitch correction to allow rapid delay change (up to 25%) without
introducing
undesirable artifacts such as pitch shifts, cliclcs and pops in the output.
So, in our
example of a one frame change in the video delay, the audio synchronizer. will
"catch up"
in just a few frames. This is well before the viewer will notice.
The combination of a programmable tally/GPI interface and a fast traclung
audio
synchronizer provides a flexible cost effective solution to the lip sync
ei~ors introduced
by production switchers and digital effects processors. It is also applicable
to systems
that use a master control switches with external effects for squeezebaclc
operation.
Figure 5 illustrates a schematic diagram of an interface to interpret the GPI
and tally
outputs and generate the necessary steering commands to control audio
synchronizers to
permit automatic correction of timing and synchronization errors, such as lip
sync errors.
The system shown in Figure 5 GPI start signals, Tally signals, and GPI stop
signals are
input to tally latches 511 and 521. The outputs of the tally latches 511 and
521, and delay
time inputs 513 and 523, are timer on/off signals and time values. These are
inputs to a
control routes 531. The control routes 531 outputs OnlOff and Tirne signals to
individual
timers 541 and 551, which in turn generate delay steering pulses to audio
synchronizers,
not shown.
-14-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
As shown in Figure 5 each of the twelve input channels consists of a GPI Start
pulse, a
GPI. Stop pulse, 511 and 521, and a Tally line, 513 and 523. The tally latches
511 and 521
are typically octal transparent, 3 state output latches, such as a 74573
series latches with a
common latch enable control, a common 3 state output enable control, 3 state
outputs.
The latch inputs can be set to operate with Tally only, GPI Start and Stop
Triggers only,
Tally gated by GPI Start and GPI Stop, as well as delay measure which may be
provided
by a 7474 flip flop, and/or a 74163 counter which are responsive to the GPI
signals. It is
preferred however that these functions be implemented with programmable logic
configured in response to and operating in conjunction with a microprocessor.
Each input channel also has a linlced delay time register 513 and 523 with a
user
selectable value from 20 ,sec (nominally zero delay) up to 6.5 seconds, in
increments of
100 ,sec. Delay times can be entered and displayed in milliseconds or in TV
fields
(NTSC or PAL). It is preferred that this function be implemented With
programmable
logic configured in response to and operating in conjunction with a
microprocessor.
Any input channel and its time value can be routed through the control router
531 to any
of the output timers 541 and 551 and each timer can steer a separate audio
synchronizer,
as an AD-3100 Audio Synchronizer. The control router is under microcontroller
control.
It is preferred that this function be implemented with programmable logic
configured in
response to and operating in conjunction with a microprocessor. Typically, the
microprocessor is at least an eight bit microcontroller with 32 I/O lines,
timers, counters,
inten-upts, priority levels, and an on-chip RAM. One microcontroller useful in
the router
531 described herein is an Intel 80C32 microcontroller. The Intel 80C32
microcontroller
is an ~ bit microcontroller with 32 I/O lines, 3 timerslcounters, 6
interrupts/4 priority less,
and 256 bytes of on-chip RAM.
The microprocessor controls a multistate transceiver characterized by a bus
interface,
-15-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
three state buffers with three state compatible send and receive directions.
The output timers, 541 and 551, provide TTL level steering pulses to the audio
synchronizer to control the delay of the synchronizer. can have different time
values and
can be turned on and off independently. Also, any timer can be controlled by
moxe than
one input channel. Assume that one switcher effect needs a one frame audio
delay and
another effect needs a two frame audio delay. Input #1 (or any other input)
can enable a .1
frame delay in Timer #3 (or any other timer) and the associated audio
synchronizer, as an
AD-3100. Any other input can be used to enable a 2 frame delay in the same
timer. It is
preferred that this function be implemented with programmable logic configured
in
response to and operating in conjunction with a microprocessor.
Program Product
The invention may be implemented, for example, by having the mutual event
detection
and synchronization as a software application (as an operating system
element), a
dedicated processor, or a dedicated processor with dedicated code. The
software executes
a sequence of machine-readable instructions, which can also be referred to as
code. These
instructions may reside in various types of signal-bearing media. In this
respect, one
aspect of the present invention concerns a program product, comprising a
signal-bearing
medium or signal-bearing media tangibly embodying a program of machine-
readable
instructions executable by a digital processing apparatus to perform a method
for
detecting video and audio mutual events, determining the delay, and applying a
synchronization delay to the audio and video.
This signal-bearing medium may comprise, for example, memory in server. The
memory
in the server may be non-volatile storage, a data disc, or even memory on a
vendor server
for downloading to a processor for installation. Alternatively, the
instructions may be
-16-
CA 02562091 2006-10-04
WO 2005/117413 PCT/US2004/015302
embodied in a signal-bearing medium such as the optical data storage disc.
Alternatively,
the instructions may be stored on any of a variety of machine-readable data
storage
mediums or media, which may include, for example, a "hard drive", a RAID
array, a
RAMAC, a magnetic data storage diskette (such as a floppy disk), magnetic
tape, digital
optical tape, RAM, ROM, EPROM, EEPROM, flash memory, magneto-optical storage,
paper punch cards, or any other suitable signal-bearing media including
transmission
media such as digital and/or analog communications linlcs, which may be
electrical,
optical, and/or wireless. As an example, the machine-readable instructions may
comprise
software object code, compiled from a language such as "C++".
Additionally, the program code may, for example, be compressed, encrypted, or
both, and
may include executable files, script files and wizards for installation, as in
Zip files and
cab files. As used herein the term machine-readable instructions or code
residing in or on
signal-bearing media include all of the above means of delivery.
Other Embodiments
While the foregoing disclosure shows a number of illustrative embodiments of
the
invention, it will be apparent to those skilled in the art that various
changes and
modifications can be made herein without departing from the scope of the
invention as
defined by the appended claims. Furthermore, although elements of the
invention may be
described or claimed in the singular, the plural is contemplated unless
limitation to the
singular is explicitly stated.
-17-
