#What is Bcast Quality
9 messages in this thread
Hello all,
Another user has been asking me about "broadcast quality" from hard disk
recorders ala the PAR. I've gotten out of my depth, so I thought I'd
throw the question(s) to the floor.
1. What constitutes broadcast quality as of Jan. 1995, beyond the
technical specs of RS-170A (or whatever it is)?
2. Are there any hard disk recorders that offer direct to air quality?
3. How serious is the artifacting on JPEG, Motion JPEG, MPEG and MPEG II
codecs?
4. What will likely be accepted for broadcast (i.e. Beta, BetaSP, M-II,
D1, D2, etc.) by:
a) Cable access
b) local broadcast stations
c) networks
5. Is there a FAQ around on this stuff?
BTW, I never introduced myself to the forum. I'm a Navy helicopter pilot
who dabbles in video and animation via 2 toasters and LW. And no, I
wasn't there, I was in Antarctica in OCT '91. 🙂
TIA,
Kent
Kent, although I don't have all the answers, I'll toss out a few thoughts from
the experience base here.
(1) Looks like broadcast quality falls back to that RS-170 standard or
CCIR 601-2 standard. Personally, if the multiburst will go through
without lopping off the 4.2 mcs portion (+/- 0.5dB) and the chroma
accuracy is there without a chroma coinicdence problem (typical of
those VHS formats that I've seen used other places), I would call it
acceptable quality. Okay, subjective. Question is, how does it come
out on the calibrated studio or production monitor?
(2) The only ones I've seen that will do direct disk to broadcast have
been at the major network level and not really in use. Although a
number of interfaces exist, I haven't seen one in actual service as
a playback source. Perhaps in another couple of years but the quality
at present seems to be limited to mid range production work with just
above VHS quality. The direct digital broadcasting thing may change
this in the near future, but the technology is still in its infancy.
(3) JPEG is the best but for single frame work, Motion JPEG is really no
more than single field/frame storage in JPEG format (TrueVision E-2000
interface cards use this method at 640 x 240 field rates which actually
translate to a 320 line resolution capability on playback). The MPEG
that I have seen looks good until you stuff a rapidly moving or
changing scene through it. Remember the lag problems we had back in
the days of the image orthacon pickups? Haven't done much with the
MPEG-2 format from an evaluation standpoint. Personally, the field
rate JPEG storage looks the best to me. I did see a system that will
facilitate around 1100 lines of resolution at a doubled rate using a
field rate JPEG storage system with interfield interpolation for a
progressive scanning reconstruction at a 16:9 aspect, but I doubt that
this will be something seen in the U. S. for quite a while, if ever.
(4) Most of our post work goes out in 3/4 U-Matic SP format (save your
BVU-950 machines) for the locals and cable companies. One of the
local broadcasters will take either BetaCam SP or U-Matic, but the
general preference is U-Matic. The major networks we have provided
material for (only CBS and ABC) would take it in BetaCam SP or one
inch C format with U-Matic being acceptable as a last choice. I
think NBC will take M-II but am not sure. We have no M-II format
capabilities here but could have provided D-2.
Internally, we do all our work with BetaCam SP, Ampex C, and U-Matic. Mostly
the BetaCam is for acquisition being immediately bumped to C for a working
copy. If one was to start off in it as a provider, I would recommend the
U-Matic SP as the format of choice for interchange since it seems to be
something that everyone has and uses. A solid standard <grin>.
Hope this helps and, like I said, nothing official in any of this, but only
some experience. Also, I am not affiliated with the forum but just a passing
through user here. This place looks like a great location for those not
dealing exclusively with consumer grade products. There is probably a FAQ on
all this somewhere in one of the libraries but I know not where.
Vince (Best of the new year to ya and keep your FLIPs current <grin>)
Hmm.
So far, I'm hearing that:
1. The PAR (M-JPEG) IS broadcast quality, and an NBC affiliate in Denver
is purchasing one for production.
2. MPEG still requires a $10K to $20K board to encode.
3. Present quality systems are limited to mid range production with just
above VHS quality.
4. Beta SP is pretty much the minimum tape standard for broadcast.
1 and 3 conflict, so I guess it depends on what you're doing. It's a
little frustrating, but the answer seems to be "If they take it, it's BQ,
if they don't, it's not." Kinda hard to pick your gear that way.
BTW, helo pilots don't need FLIPs, just the pocket version of the
Rand-McNally. <VBG> Happy New Year.
Kent
Kent, problem is that I really don't have that much of a knowledge base on the
in progress MPEG developments so the info I relayed could well be way out of
date. I noted the other message on it and figured that I should pull my reply
before it went out, but what the heck <grin>. There will be quite a few in
here with much better knowledge of what is going on in the world of nonlinear
editing than I since we dont't work with it yet.
"pocket version of the Rand-McNally", eh? Can't miss those burger stop exits
<LOL>. What always amazed me was the "controlled crash" landings on the deck.
Geeze! That would scare me to death! Need lots of room for a 141 but I see
where they are doing deck landings with a 130 now.
Vince
>deck landings with a 130…<
Well, yeah, but I don't think they have much payload on takeoff. The
Herc's a great plane, but I think the carrier stuff was a one time only
test, sorta like with the U2.
Besides, any LZ bigger than 50' x 60' is for insecure types. <g>
Are you a MAC pilot?
Kent
Kent, not an active duty type but one of those retired from the world of
"spookdom" who had to be rated on certain types just in case. Of the total
team, we had coverage on almost every thing in inventory. I had the "trash
haulers" <grin>. About your "any LZ bigger than 50' x 60' is for insecure
types", with that job, you got that right <LOL>!
Vince
<<1. What constitutes broadcast quality as of Jan. 1995, beyond the
technical specs of RS-170A (or whatever it is)?>>
-This is tough one since it is more a subjective standard to measure. The issue
is the amount of noticable artifacts you get depending on a number of playback
conditions. JPEG seems the best current scenario for the average DTV user.
<<2. Are there any hard disk recorders that offer direct to air quality?>>
-Avid has a box called "Airplay" that is currently in use by broadcast stations
around the country. Also Quantel has some kind of playback box. I am using the
Data Translations Media 100 which has (to my subjective opinion) the best
compression available. They use a Component option which records 4:2:2 video on
the YRB inputs of a BetacamSP deck. recently they began offering an HD option
which used a hard disk array for extremely good video quality (Near D-2!)
<<3. How serious is the artifacting on JPEG, Motion JPEG, MPEG and MPEG II
codecs?>>
-Once again it's all subjective…. MPEGII has a promising future, but the
price has to come down and it requires some special functions for
frame-accurate editing with Time-Code. Most of the current DTV devices use
JPEG.
<<4. What will likely be accepted for broadcast (i.e. Beta, BetaSP, M-II,D1,
D2, etc.) by:>>
a) Cable access -3/4" Umatic
b) local broadcast stations -BetacamSP, 1" Type c
c) networks -BetacamSP, D-2
Hope this helps!
-Mitch Hill/Hill Creative Services
I have noticed many people asking the question "What is Broadcast Quality?
Maybe I can shead some light on this.
The FCC has set a standard for the quality of a video signal to be broadcast,
be it sent by whatever method, ie, air, satelite, fiber-optic,
or cable. That basic standard is known as RS 170A. You would need a waveform
monitor and a vectorscope to actually see or measure
the signal to insure that it complies. There are boards available for the
computer that will turn your wideo monitor into a waveform monitor
and vectorscope. These are the main specifications:
Vertical Blanking 21 lines
Horizontal Blanking 10.49-11.44 micro seconds
Sync Level 40 IRE units
Burst Level 40 IRE units
Black or Pedestal 7.5 – 10 IRE units
Peak Video Level 100 IRE units
Chroma Level 120 IRE units
There are many more measurments, such as subcarrier/Horiziontal Phasing, the
front porch, back porch, breezeway ( I don't know where they got these names !
), pre & post equalizing pulses, etc., but these are the main ones, and when
these are correct, the others generally fall in.
In a television facity, great care is (should, anyway) taken anytime a dub is
made, or editing of material, to ensure the quality of the signal.
In fact, the signal itself is quite unstable, and degenerates rapidly with
dubbing and editing, due mostly to the mechanical nature of the wideo tape
itself. It actually stretches and relaxes, and while this is almost
immeasurable, it creates timing problems in the signal. The television
facility uses Processing & Distribution Amplifiers and Time Base Correctors to
maintain this critical timing of the signal.
Before any program is "aired", a Technical Evaluation is performed on the
program, which is viewed, full-length, and the specifications listed above are
measured and documented, along with audio information, captioning, format, amol
encoding information, etc.
Anyway, this is a most basic of 'primer's', but it gives an overview of what is
meant by 'Broadcast Quality'.