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VITC help

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lloyd stas
VITC help
on Jan 26, 2009 at 2:41:31 pm

Hi, just got some delivery requirements and not sure about something..



"We require broadcast standard 625/50 (PAL) @ 720x608 resolution including VITC on lines 19 & 21 and TeleText (if included) on line 335."


I'm stumbling at the VITC part. I dont really understand what this is or what I should do about it.

Thanks :)
Lloyd



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lloyd stas
Re: VITC help
on Jan 26, 2009 at 3:04:03 pm

oh and also..

have been asked to supply with video bitrate of 50mbps. Is this the same as data rate? when I compress with Squeeze, wont let me give it more than 9570 kbps data rate.



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Keith Troester
Re: VITC help
on Jan 26, 2009 at 9:31:40 pm

VITC is the "more accurate" form of timecode, in that you can play down to frames/fields when jogging, for instance, on a DigiBeta. VITC is part of the vertical interval, and thus cannot be read at very high rates of deck speed, just like picture can't be vividly read at high speeds. If you're sitting on a frame, VITC can still be read.

VITC complements LTC, which is typically part of the audio channel/bandwidth of the tape, and is only so accurate. The tape stops, and so does the audio and the LTC. Your timecode reader on the deck can show you both, and you can also see the VITC/LTC lights on the deck when they are active.

You control VITC placement in the deck menu, and make sure VITC is on. PAL is typically lines 19,21 for VITC, NTSC 16,18. You obviously don't want VITC creeping into active picture. Ideally, VITC is set with a space between, and not consecutive lines.



http://www.keithtroester.com
PHOTOS | VIDEOS | SOUND | ETC.


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Dave LaRonde
Re: VITC help
on Jan 26, 2009 at 9:38:31 pm

VITC stands for Vertical Interval Time Code. It's described above.

So how are you supposed to DELIVER this video? As a file? On tape? It certainly SOUNDS like you'd deliver on tape, and my guess (and it's ONLY a guess) is that it would be Digibeta.

I'd ask the people receiving the video for some clarification. It won't be a dumb question, and it's a LOT better than delivering the wrong thing.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Baz Leffler
Re: VITC help
on Jan 26, 2009 at 11:07:24 pm

Broadcast specification for deliverables on any tape format is that the VITC and LTC be identical which is mostly done automatically by the deck so long as you haven't messed with the 'normal' settings.

A quick way to check for this while recording is to watch the VITC at the same time as the actual timecode numbers. The VITC displays at the top of the picture from 'frames' on the left to 'hours' on the right all in 'binary'. When you get to zero frames there should be a large (ish) gap at the left side which is binary for zero. Remember there is 'user bits' in the VITC which is indispersed with the actual timecode (as well as sync data). By watching the natural flow of numbers you will see a similar 'pattern' in the VITC. Subsequently, when the timecode goes thru say, 10:00:00:00 most of the VITC data will 'disappear'.

Binary vitc is as follows (based on [8] [4] [2] [1])
00
01 -
02 -
03 --
04 -
05 - -
06 --
07 ---
08 -
09 - -

Baz

What would I do without the 'UNDO' button!!!!


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lloyd stas
Re: VITC help
on Jan 27, 2009 at 10:43:33 am

woah, this is heavy. think i may be in over my head.. haha.

I have to upload a file via FTP to them. Here are the delivery specs they have asked for:

File:
Video Codec: MPEG-2 422P@ML (4:2:2 Colour space) Program stream
Video Bitrate: 50 mbps I Frame Only GOP structure
Resolution: 720x608 (we can accept 720x576)
Aspect Ratio: 16:9 (14:9 text safe)
Frame Rate: 25
Rate Control: Constant Bit Rate (CBR)
Audio Codec: Mpeg 1 layer 2 (we cannot accept uncompressed PCM audio)
Audio Bit Rate: 384 kbps
Audio Sample Rate: 48 kHz
Field dominance: 1st field / Upper field first.

We require broadcast standard 625/50 (PAL) @ 720x608 resolution including VITC on lines 19 & 21 and TeleText (if included) on line 335.











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Denis Murphy
Re: VITC help
on Feb 18, 2009 at 11:45:49 pm

Sounds like you might be delivering to IMD Adsat? If so, contact them and ask what encoder they recommend. I use Episode to create the 50mbps i-frame only digital master. Adsat actually recommended this to me, and provided a preset.

Getting the VITC into the file is a bit hit and miss. You should be able to export a timecode enabled quicktime from your editing software. Then, that TC should translate to VITC in the Episode-created mpeg2 file. That said, I've had trouble with that - it's hit and miss. I was successful with a combination of Episode 4 and Final Cut Pro 5, but something seems to have broken in subsequent versions of either FCP and Episode and any masters I've created since upgrading from those versions have been VITC-free.

But if you are in fact dealing with Adsat, they have a means of adding the TC at their end, so you might ask about this.

Best of luck, and if you figure out a definitive way to do this, I'd be interested in knowing.

PS I always supply at 720x576 (wonder if that's why no VITC coming through, perhaps only the 608 line version has the correct structure for VITC, must test this!)



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cowcowcowcowcow
Adam Jakubowski
Re: VITC help
on Apr 9, 2009 at 10:47:41 pm

Hi Lloyd & co,

The actual reason we state both 720x608 as well as accepting 720x576 material in our specs is from a legacy requirement when recieving commercails that are originally ingested from a master tape direct to MPEG2. Examples of hardware encoders that can do this include Telestream's ClipMail Pro, Content Agent & Digital Rapids StreamZ.

As the world starts to migrate to a tapeless workflow (negating the need for physical tape masters) and smaller post houses or individuals cannot justify the costs of a Digibeta VTR, we are able to accept material without the Vertical Blanking Interval (VBI) included, thus a standard frame size of 720x576.

The only requirement we have for non-608 material is that TC is embedded and continuous which we can then reference and synthesize into our required VITC information.

The only situation we would stipulate that the VBI area be included is when the commercial has teletext (Line 22/335) embedded otherwise this information is not retained within 720x576 media and will be lost.

As Denis has mentioned (who i have worked with directly), please feel free to contact us if you require any advice or assistance in delivering material to IMD (IMDAdsat).

Kind Regards,

Adam Jakubowski

Technical Services Manager
Independent Media Distribution - IMD
http://www.imdplc.com


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Mathew Paul
Re:VITC
on Oct 16, 2011 at 7:23:11 pm

Hi,

I am new to the time code analysis. Please correct me if any mistakes,

1. For a 720x608 MPEG-2 422 @ML stream of PAL [25 FPS interlaced]type 32 lines of VBI data, in which line i can find vitc information?

2. The vitc bit group of 90 bits starts from the beginning of line or with any specific offset is required to find the group?

3. In what bases i can search for the starting location of vitc information in a line?

Thanks


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