TV system attribute in h264 HD files

[cniedzi]

Hi.

I have question about video system flag attribute in h264 @1920x1080 file (see example below). I've search Internet but I haven't find any satisfied answer...

What is a purpose of this attribute in HD h264 files?

I've encoded h264 file with one of the comercial encoder and it set video system to false parameter (NTSC instead of PAL) - see example below. Is it possible to change this attribute from NTSC to PAL without reencode? Or, maybe this totaly doesn't matter in HD movies...


Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 7mn 22s
Bit rate mode : Variable
Bit rate : 5 000 Kbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.217
Stream size : 263 MiB (94%)
Language : English
Encoded date : UTC 2013-11-04 19:47:34
Tagged date : UTC 2013-11-04 19:47:34
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

[Guest]

It's a VUI parameter (video_format) and most likely has no effect on playback.

[benwaggoner]

It's a VUI parameter (video_format) and most likely has no effect on playback.
But to the extend it did have an effect (which seems unlikely) it wouldn't be a good one since NTSC isn't ever 25p.

I think the PAL/NTSC format flag is only supposed to be applied to standard def content that otherwise fits the Level 3.0 restrictions of that content (so max 720x480 30 fps for NTSC and max 720x576 25 fps for PAL).

I've never heard of a decoder using these. The only thing I could imagine them being used for is to figure out a default Rec. 601 transform when the content color space isn't otherwise specifically defined.

[zerowalker]

Can it have some affect on Deinterlacing?
This clip is progressive as far as i can see, but i know personally that TV broadcasts are quite a mess, where they can have it flagged "Interlaced" when it's progressive.

So i wonder if the NTSC flag can cause a BFF deinterlace instead of TFF?

[kieranrk]

But to the extend it did have an effect (which seems unlikely) it wouldn't be a good one since NTSC isn't ever 25p.


There is some weird hybrid in some parts of South America.

[benwaggoner]

There is some weird hybrid in some parts of South America.
As analog broadcast format, yeah, there are all sorts of oddball mixes around the world. But I've never heard of it being used for a digital stream. Same way that France used SECAM for broadcast, but post was all PAL, and AFAIK no one ever made a SECAM flagged bitstream for DVB or anything else.