MPEG - VITC Information Encoding

[Dave1024]

I want to know VITC [vertical time intervel coding] encoding techniques.

Please help to solve the following queries

1. what are the methods for encoding vitc.
2. how can i detect the embedded vitc info in a mpeg 2 stream
3. which is the standard supports VITC?
4. VITC is only with MPEG 2 or it will come with other codec's?
5. usually how many lines i want to crop for remove this VITC information

:thanks:
Dave

[pandy]

VITC is embedded on lines before line 23 (PAL systems*) thus is not coded on MPEG.

First half of line 23 (PAL systems*) is used for WSS signal and it can be embedded to video coded as MPEG.

*PAL systems is used as 25 fps system not color coding method.

[kieranrk]

VITC goes in the MPEG-2 or MPEG-4/AVC bitstream. In theory it can also be coded in DVB-VBI.

[pandy]

can be embedded as user data or as separate PID (DVB case - RAW VBI for example) however it is not coded as video inside MPEG/H.264.

[drmpeg]

can be embedded as user data or as separate PID (DVB case - RAW VBI for example) however it is not coded as video inside MPEG/H.264.
It can be coded as video in 4:2:2 profile. That's why the number of lines per frame was expanded in 4:2:2@ML (from 480 to 512 for 525/60 and from 576 to 608 for 625/50).

Ron

[Dave1024]

Hi,

Did all the streams with MPEG-2 4:2:2 MP have defiantly 32 lines VITC information available on top of the frame?

Thanks
DAVE.

[kieranrk]

can be embedded as user data or as separate PID (DVB case - RAW VBI for example) however it is not coded as video inside MPEG/H.264.

It goes in pic-struct SEI in MPEG-4/AVC

[drmpeg]

Hi,

Did all the streams with MPEG-2 4:2:2 MP have definitely 32 lines VITC information available on top of the frame?

Thanks
DAVE.
No, it's entirely optional. It's also pretty uncommon. In the 18 years I've been in the MPEG industry, I've never seen a 512 or 608 line 4:2:2 bitstream. However, they do exist. Mostly used for distribution.

http://www.grassvalley.com/docs/PDFs/whitepapers/pdr300/Profile-wp-optimize.pdf

Ron

[Dave1024]

Hi,
Thanks to your replay.

How can i understand the presence of VITC in an MPEG-2 streams?- i mean how a generalization is possible ?
Is this is available with time code headers ?

Thanks
DAVE

[drmpeg]

Hi,
Thanks to your replay.

How can i understand the presence of VITC in an MPEG-2 streams?- i mean how a generalization is possible ?
Is this is available with time code headers ?

Thanks
DAVE
If the bitstream just has timecode (either GOP header or pic_struct in a picture timing SEI), you really don't know where it may be coming from. It could be VITC, but most likely (at least with MPEG-2 GOP headers) it's just a timecode that starts at 00:00:00 when the encoder is initialized at start-up.

These headers are also optional. Many MPEG-2 streams that I see from cable networks do not have GOP headers.

Unless you know for a fact that a certain encoder is actually transferring VITC timecode into GOP or SEI timecode, you can't make that assumption.

VITC is often used for authoring encoders so that they can create frame accurate clips (the start and stop frame is controlled by the VITC timecode). However, they do not necessarily transfer the VITC timecode to the GOP or SEI timecode.

Ron

[pandy]

It can be coded as video in 4:2:2 profile. That's why the number of lines per frame was expanded in 4:2:2@ML (from 480 to 512 for 525/60 and from 576 to 608 for 625/50).

Ron

but this is not MP but probably HP? MP limiting MB number.

[pandy]

It goes in pic-struct SEI in MPEG-4/AVC

http://iphome.hhi.de/suehring/tml/doc/lenc/html/sei_8c.html

as a InitUser_data_unregistered ?

[kieranrk]

http://iphome.hhi.de/suehring/tml/doc/lenc/html/sei_8c.html

as a InitUser_data_unregistered ?

Sorry, not pic-struct SEI - that doesn't exist. I mean Picture Timing SEI in the clock_timestamp fields.

[drmpeg]

but this is not MP but probably HP? MP limiting MB number.
There are separate 4:2:2 profiles in MPEG-2. 4:2:2P@ML and 4:2:2P@HL.

4:2:2P@ML allows for 608 line 625/50 images and 512 line 525/60 images. The 4:2:2P@ML maximum bitrate is 50 Mbps.

4:2:2P@HL is still limited to 1920x1088 (there's no analog VBI in HDTV). The 4:2:2P@HL maximum bitrate is 300 Mbps.

11 bit intra DC precision is allowed.

4:2:2 profile was added to MPEG-2 in 1996, so it's been around for quite a while.

Ron

[drmpeg]

There are some 4:2:2P@ML bitstreams here:

http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_13818-4_2004_Conformance_Testing/Video/bitstreams/422-profile/

Ron

[drmpeg]

I almost forgot, I have a 4:2:2P@HL version of "Big Buck Bunny" on my website.

http://www.w6rz.net/bbb24p_00.zip

It's coded at 70 Mbps with a flat (all 16) intra quant matrix.

Ron

[Mug Funky]

i've seen 50mbps 4:2:2 HP:HL 512 line stuff before with VITC burnt in.

i think some broadcast server things store their content this way - it was delivered to us straight from a broadcaster.

[Dave1024]

Hi,
I would like to know which are the instances in which the display height and width is different from the actual resolution.[the display height and width is got from the extension data]. The reason behind my doubt is for eg : an HD with 1440x1088 is stripped the top 8 lines and the display is 1440x1080. This 8 lines is VBI info or what type of meta data is present there ? - I would like to generalize the instances in which the VBI info is present in some streams.

Thanks
Dave

[Blue_MiSfit]

MPEG IMX D10 stores NTSC video in 720x512i I believe. I actually record in 720x512i with 4:2:0 chroma and an IBI GOP structure every day.

This is to preserve closed captioning (line 21) for immediate playback from a server which only supports CC in this fashion.

In my case, VITC is of no concern.