[georgia]

here's some info about Soundmaster and VVTR.. Also Soundmaster now has a VVTR mode, a VVTR loose mode and a VVTR 1 frame mode. iF you have a video file that the frame edges are not perfect, contact soundmaster and they should be able to hook you up with the new settings...

Just a quick note to summarise the whole situation with respect to
VirtualVTR Pro, Kona3 and Soundmaster on Film Mix Stages,
particularly running 23.98 @ 29.97 configurations.

We have worked with Soundmaster and AJA over the last few weeks to
put into place a setup which covers pretty much all the bases you
will meet on a mix stage, ensuring frame accuracy and tight lock,
even when cross locking 23.98 material to an otherwise 29.97 world.

AJA Have created a beta version of a new Kona3 driver with a special
function we can call to precisely determine the frame on the air,
even when operating in 3:2 pull up or with cross locked timecode.
This driver along with the latest VirtualVTR Pro seems to work very
well.

The new Kona3 driver should be available on request to AJA, the one
we are using is:
Kona3_2006-12-13@10_57_14

NOTE: This is designed as a comprehensive explanation of the
technical considerations surrounding the use of VirtualVTR Pro on a
mix stage, with AJA Kona3, and Soundmaster ION, playing a variety of
video formats with the option of 23.98 to 29.97 cross locking. Its a
technical guide for ENGINEERS, not a user guide. Please do not
reproduce this information (some is proprietary) for the time being.

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- QuickTime, VirtualVTR Pro and Kona operate in either a 'scheduled'
or 'unscheduled' video playback mode depending on a number of factors
which are determined as the movie opens. Scheduled mode prepares 30
frames in advance and gives them a target 'delivery' time to air to
be handled by the Kona driver, whilst Unscheduled mode has QuickTime
sending out 1 frame at a time through the software/hardware pipeline.

- In unscheduled mode, in some cases, there can be a situation where
the current time reported by quicktime is slightly offset from the
actual frame which is on air (typically less than a frame, but can be
as much as a frame). Also, in some cases the QuickTime perception of
time may be working on a frame edge offset from the real frame edge.
This can lead to rounding errors, once again affecting overall sync.
Whilst it is still possible to get good results in unscheduled mode,
there is a greater possibility for occasional sync mis-locks, and so
wherever possible, Scheduled mode is preferred. In Unscheduled mode
you will need to determine and enter the 'sync correction' parameter
in VirtualVTR for the codec in use, compensating for codec, video
hardware and then projector latencies.

- In Scheduled mode, QuickTime prepares a series of frames in
advance, and tells Kona when each frame belongs on the air. This has
the added benefit of having a cache of frames ready in the driver and
can make for smoother playback with challenging media formats like
DVCProHD, particularly where the CPU is working hard. In theory if
we ask QuickTime for the current time, it will tell us, and in theory
the frame targeted for that time *should* be on the air. However, in
practice the slewing process used by Soundmaster will 'slip' the sync
between 'proposed time' and 'actual time' for the delivery of the
frames (not least because variations in speed during slew will put
the QuickTime timeline frame edge out of sync with the genlock edge).
Consequently it is not safe to 'take Quicktime's word for it' when
reporting timecode back to the Soundmaster. Fortunately AJA have
provided a mechanism which allows us to bypass or correct QuickTime's
own perception of time, and replace it with a literal report of which
frame has actually 'just left the building'. This offers superbly
accurate sync. In Scheduled mode the 'sync correction' parameter in
VirtualVTR is theoretically zero, but you may need to enter a value
to compensate for projector latencies.

There are a number of factors which determine whether QuickTime
selects Scheduled or Unscheduled mode when opening a movie.
Essentially QuickTime builds a 'codec calling chain' as it opens a
file, figuring out what steps are required to get from the Movie file
(in a compressed format typically, at a certain size) across to the
Video Output (which might expect uncompressed frames, at a specific
size). QuickTime asks the Video card driver what format of video it
expects. If mismatches exist between source and destination, then
QuickTime has to put processes into the calling pipeline to correct
for these. Typically, if QuickTime includes conversion processes, it
will choose Unscheduled mode of playback. If there are no
mismatches, it will choose Scheduled mode. So, then simplest way to
ensure scheduled mode is to make sure your Sound movie matches the
basic format requirements of the Video card driver (eg. uncompressed
8-bit, full frame size).

As we are aware in practice, it is rare to see a movie in
uncompressed format arrive on a mix stage, and fortunately, there are
still lots of configurations where things dont match 1:1 and we can
still get scheduled playback. For example - The Kona driver natively
expects 8 or 10 bit uncompressed Video at 720x576, or 720x486 (SD) or
1920x1080, 1280x720 (HD). However, it *also* supports a range of
other codecs and sizes *natively* which means that QuickTime doesn't
have to install a pipeline processor, and scheduled mode can work.
The other parameters Kona will accept include

FRAME SIZES:
- 720x486, 720x576, 1920x1080, 1280x960 (standard sizes)
- 720x480 frame size (particularly for DV-NTSC video frames which use
this size - it will center the picture, not stretch)
- 1440/1280x1080 frame size (particularly for DVCProHD 1080 video
frames which natively this size - it will stretch the picture)
- 960x720 frame size (particularly for DVCProHD 720 video frames
which natively this size - it will stretch the picture)
- 640 x 480 (not sure whether it stretches or centers)
- 320 x 240 and some other offline RT sizes (stretches)
CODECS:
- 8 and 10 but 2vuy or v210 (standard uncompressed codecs)
- DV25, DV50, DVCProHD
- MotionJPEG, PhotoJPEG
- Avid Meridien
- IMX (??? not certain of this)
- Some other uncompressed codecs with color components in different
arrangements.

If you are using a frame size which doesn't match, or a codec which
doesn't match, then its likely playback will be unscheduled.
VirtualVTR Pro indicated Scheduled or Unscheduled playback using a
Green or Red 'Disk' LED which shows the number of cached frames (this
is always zero in the case of unscheduled playback).

- VirtualVTR Pro superimpose Graphics buffer.
VirtualVTR Pro also has the option of inserting a video frame buffer
between QuickTime and the Kona, where graphics can be superimposed
(or it can be used as a conversion compatibility layer). Like any
other pipeline processor, this causes the chain to be built in
unscheduled mode. However for some more exotic codecs, like H264,
HDV, DNxHD and MPEG2, it may be necessary to use the Graphics buffer
as a translation layer, and live with unscheduled mode. These codecs
are interframe and typically long GOP which makes it almost
impossible to deliver them directly to the Kona card without
processing. VirtualVTR Pro can allow you to play these formats direct
to air, but you will have to use the Graphics overlay buffer. The
other option is to convert the format to DVCProHD or medium Q
PhotoJPEG before opening in VVTR Pro (this technique *would* allow
Scheduled mode, but takes time before you can work).

- Making Scheduled Mode Sync accurate
As described, Scheduled mode is good, but we must get data from the
Kona card not from QuickTime if we are to report time accurately. In
regular framerate=timecode modes, we can simply ask the Kona every
timecode frame, which video frame is on the air. This gives very
accurate results. However there are times when Kona cannot return
this information, particularly during slewing (during which time QT
operates in unscheduled mode), also, when cross locking (playing
23.98 picture with a 29.97 timecode - Soundmaster locked to NTSC),
the information from Kona would not correspond directly with the
timecode and Soundmaster reference, so we use a variation technique,
called XCheck (in VVTR Pro prefs).

Essentially, the prefs you need are ' Query VOut for Time' - to make
VirtualVTR Pro use the Kona representation of Time during Scheduled
playback. In Unscheduled playback this is ignored. Also, the
'XCheck' additional mode uses a more advanced call, only available in
Kona3.3+ which makes the Query Vout mode work properly when cross
locked. It should be safe to leave both these options turned ON at
all times and it will use them when available, or defer to other
techniques when not. There is one exception to this rule - if your
synchroniser expects to watch the 9-pin 'Servo Lock' status flag
(Soundmaster does not, I believe) then you will find that the Servo
Lock flag never comes on in a situation where Query VOut is selected,
but scheduled mode is not used (since we are waiting for the
Scheduled mode to settle *before* we enable servo Lock).

- 24, 30 and Pull Down considerations
VirtualVTR Pro has a 0.1% pull down option which will automatically
conform a movie when opened from 24 or 30 FPS to 23.98 or 29.97 FPS.
Note that it does NOT process the sound, so after pull down you must
ignore the embedded audio in VirtualVTR Pro since it will be out of
sync. If you prefer other pre-processing QT conform tools exist
(cinema tools ?). Normally the VirtualVTR Pro conform will be non
destructive - ie. if you close the movie it will rever to 24/30 FPS.
However if you TIMESTAMP the movie whilst it is open and pulled down,
this will permanently conform the movie file to the pulled down rate.
A very useful tool in VirtualVTR Pro is the 'Get Info' in the bin -
select this when a movie is closed, and you will see the Movie and
Media Timescale and the frame duration values - these are the
fundamental QuickTime time units which the movie is built with. Most
common will be 2500/2500/100 for a PAL movie, 2997/2997/100 for an
NTSC movie, and 23976/23976/1000 for a 'perfect' 23.98 movie. You
might see the first parameter set to 600 which is a common error
caused by QuickTime player - however if you have the VVTR Pref
'Correct Movie Timescale' set, this will be corrected as the movie
opens, to match the second parameter. The first parameter is used to
locate VVTR frame by frame, so its quite important that it
corresponds to the actual frames. You might see 24/24/1 for a 24 fps
movie, 25/25/1 for PAL or even things with 80 as the duration
(instead of 1, 100, or 1000). This is where you should take care.
Values like 2398/2398/80 are NOT accurate enough because of rounding
errors (whereas 23976/23976/800 is), and the 80 duration movie (which
might be something like an NTSC export from a 24 FPS movie), is
likely to have a long term sync drift. In particular when exporting
from a Film Composer (24 FPS) it is VITAL that the user does NOT try
to 'create' a 29.97 or a 23.98 movie- this will most likely cause the
situation described due to inaccuracies. Instead the FilmComposer
should output a true 24 or 30 FPS movie, and VVTR Pro will pull it
down during playback.

- Playing 24 FPS SD movies Progressive on a projector.
As we all know, there is no 24 FPS standard definition video mode.
However you will all have come across 24 FPS SD Quicktime movies,
from Avid Film Composer, or Final Cut Pro (typically Avid Meriden
format or DV format). On a film Mix stage there is a great desire to
preserve the 'true to film' 24 FPS progressive scan material and
project it in this format without corrupting the integrity with the
traditional 3:2 pull up and interlacing of the picture. Fortunately,
AJA have again come to the rescue, and Kona3 has a 24 FPS SD native
display mode, and a hardware upconvertor which allows you to play a
24 FPS Avid (or DV) Movie in fully Scheduled mode, with Kona
upconverting to 1080 24p (or 23.98p) on the HD-SDI output. This
offers your customer a 24p Progressive screening of their QuickTime
movies, which is as close to mixing against film as you are going to
get these days. This can all be done, even on a stage which uses NTSC
sync and 29.97 FPS Timecode to the Soundmaster (you will require a
coherent NTSC and TriLevel sync generator).

VirtualVTR Pro and Kona offer the most flexible playback platform for
Mix Stages, supporting most common desktop video formats natively
with no conversion.

Clearly there is alot of information in this document, which we have
chosen to share with you so you are fully educated. However in
practice users of VirtualVTR Pro do NOT need to know all this:

You may want to define a fixed set of video formats which you are
willing to accept from your customers (just like you do with the
linear decks you have available), and then define a set of prefs for
your operators to match each incoming format. You can always expand
your list of accepted formats over time. In your specification you
should clearly define the video frame size and the codec.

Just like your users don't understand the technical details of HDCam
tape, they do know which machine to put it into, and which buttons
to press. So it is with VirtualVTR Pro - define some standards for
your customers and have a fixed user process for dealing with each
standard. In these times where there are hundreds of format
variations it's vital to nail it down to some extent. We have done
everything possible to ensure that the widest range of movie formats
will play, without conversion, and with accurate sync, but there are
limits to what is possible and this is where you must create some
boundaries. In most cases the last resort is to convert (and perhaps
scale) the movie with QuickTime player into one of the supported
formats, and in general this will allow an almost unlimited range of
incoming formats.

Our system now works with "pro" and "not so pro" video files.


cheers
geo