PAL and NTSC???

[John Rofrano]

[Juan Juig] “HOWEVER even though I clearly chose the 25.000 PAL frame rate, as I open the video wih MediaInfo it says that the frame rate is 25.000 and that standard is NTSC, even though I chose Pal. Why is that so??”

It might be a bug in MediaInfo. NTSC does not support 25 fps so I don’t see how MediaInfo could mistaken it for NTSC unless it was a bug.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Juan Juig]

Thank you for your reply.

That’s what I thought too… But media info identifies all of my 25p mp4 exported videos as NTSC standard.

And I even checked video information with MediaInfo on seperate computer with different versions of MediaInfo.

Therefore I can only assume it’s a bug. Is there another probable reason for this odd thing?

[Jerome Martinez]

NTSC does not support 25 fps so I don’t see how MediaInfo could mistaken it for NTSC unless it was a bug.

In e.g. MPEG-2 Video, there is a bitstream field for the standard (“extension_start”, “Sequence display”, “video_format”), and another one for frame rate (“sequence_header”, “aspect_ratio_information”). Same for AVC.

In MediaInfo, “NTSC” is displayed if:
– “video_format” bitstream field is set to “NTSC”
– width and height is 720/704 and 486/480 (there is no test on the frame rate, maybe I should add one…), impossible here (1080 lines).

Your file (its encoder) is buggy if “video_format” is set to 2 (“NTSC”) instead of of 5 (“Unspecified video format”) with a 1080p25 fps stream.
From specs: “video_format indicates the representation of the pictures as specified in Table E-2, before being coded in accordance with this Recommendation | International Standard. When the video_format syntax element is not present, video_format value shall be inferred to be equal to 5.”

Jerome, developer of MediaInfo.

[John Rofrano]

[Jerome Martinez] ” (there is no test on the frame rate, maybe I should add one…),”

I guess you have to decide if you want to trust the metadata or the stream format? If the frame rate is 50i, 50p, or 25p it’s PAL regardless of what the metadata says. Since trusting the metadata (which in this case is obviously set wrong by Sony) your users assume that your program has a bug because they can clearly see it’s PAL video from the frame rate.

I would recommend that frame rate overrides the metadata and reports it as PAL video.

BTW, MediaInfo is an awesome program that we recommend here a lot. Thanks for writing it.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Jerome Martinez]

I guess you have to decide if you want to trust the metadata or the stream format?

MediaInfo aims to display information from the file. there is a “video_format” field in the bistream, I display what is in that field.
I prefer to educate people that cheating on the stream: the stream is bad, complain to the company who encodes it (even if it is Sony).
I understand that people prefer to discard such issue, but I did not choose this policy.

I would recommend that frame rate overrides the metadata and reports it as PAL video.

Rely on me for never doing that ;-).
If there are incoherencies and if I implemented the detection (incoherencies detection is a hard job, very long, I priotize depending of sponsorhips), I will display both values (the metadata one and the detected one) but I’ll never hide the bug from the encoder.
I consider MediaInfo as having the right output because I report the information from the bitstream. But I am thinking to split this line in 2: one for the “detected” standard, one for the “reported” standard.
I already have several coherency tests but I don’t have this one, this is the main issue I see and I put it on my (long) todo-list.

BTW, MediaInfo is an awesome program that we recommend here a lot. Thanks for writing it.

🙂

[John Rofrano]

[Jerome Martinez] “Rely on me for never doing that ;-).”

Too late… You are already doing that! 😉

You said:

“In MediaInfo, “NTSC” is displayed if:
– “video_format” bitstream field is set to “NTSC”
– width and height is 720/704 and 486/480 (there is no test on the frame rate, maybe I should add one…), impossible here (1080 lines).”

So you are already guessing by looking at the width and height. If you would never do that, then there should only be one check and that is what the video_format field says. So I was just suggesting that you be more intelligent in your guessing to include frame rate with width and height since it’s these three things together that determine if something is NTSC or PAL compliant.

I agree with you if the purpose of MedaiInfo is to report what it finds in the video file and not guess then it shouldn’t make any inferences at all. Of course, flagging discrepancies would be a nice touch. 😉

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Jerome Martinez]

So I was just suggesting that you be more intelligent in your guessing to include frame rate with width and height since it’s these three things together that determine if something is NTSC or PAL compliant.

Implemented.
For this file, no change in MediaInfo display because “video_format” field has currently the priority (the “auto-detection” is done only if “video_format” field is missing).

If you would never do that, then there should only be one check and that is what the video_format field says.

I wanted to mean that I’ll never hide the value from the “video_format” field.
There is definitely some incoherency here in MediaInfo output, and this is the reason I am thinking to split the line (1 line, 1 test).
I just don’t want to hide the “video_format” field even if it is wrong. I think I’ll move it to a “Reported standard” line but I need to think a bit more about it, never good to change things too quickly.

What I have in mind is to display something like:
Standard: Full HD
Reported standard: NTSC

[Juan Juig]

Thank you for all the replies. I am still confused about what is causing this.

Here are screenshots of my project and export settings.

I hope this will reveal my problem.

[John Rofrano]

[Juan Juig] “I hope this will reveal my problem.”

This is not your problem to solve. Sony does not supply any AVC Internet templates for PAL. Obviously, changing the frame rate to PAL doesn’t change the metadata in the stream from NTSC to PAL. So this is a bug in Sony Vegas Pro. You can report it to Sony but I hight doubt it will ever get fixed. Just ignore it.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Juan Juig]

But could this bug affect anything? I mean is the video still PAL and only metadata is incorectly shown or is it actually a NTSC wanna-be video that will cause trouble if I want to import and manipulate it in programs such as Media Composer? Is this affecting video characteristics? Is the video “ruined” in any way?

I hope you know what I want to say..
And thank you so much for taking you time and replying!