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Is there a way to detect if a file has or has not Vbi data this way! I.e if a Pal videofile with the reported 720x576 has Vbi data the actual height is an additional 32 lines = 608.

SD pal file VBI = 720x608

I am not interested in the info in those 32 lines - I just want to know if they are present or not ( to be able to make an decicion)

So far from what I can see ffmpeg and Medialinfo reports my VBI samples as 720X576 - but I know they are 608.

Maybe I am using the wrong tools or the wrong flags / cli arguments?

Many tnx!

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    It would be very unusual for the horizontal and vertical blanking to be included in an encoded digital file. Why do you believe that these files have that information?
    – Jim Mack
    Commented Aug 8, 2015 at 17:20
  • Because fx Carbon detects the file as 720x608 - and will output these lines unless I crop of 32 lines on the top. ( Carbon has an automatic detection / crop also - because other workflow Considerations I can't use that)
    – Johan Skaneby
    Commented Aug 8, 2015 at 17:45
  • Sorry to be dense, but are you talking about a digital file on disk? If so, what type is it (container and codec)?
    – Jim Mack
    Commented Aug 9, 2015 at 12:51
  • Yes - we are talking about a digital file, correct. So far LXF and Mxf. long gop Mpeg 2 inside
    – Johan Skaneby
    Commented Aug 9, 2015 at 13:03

1 Answer 1

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Containers like LXF/GXF/MXF allow EIA-708 (VBI) streams but as far as I know they do not encode the video data -- the blanking interval -- that originally contained those streams. That would run counter to the idea that codecs embody, that of squeezing out redundant information. I could be wrong, but I've never seen or heard of a codec that encodes invisible lines.

You could scan the file for the packet headers that identify caption / VBI streams, and if you find them you could impute a frame size that would have contained them, but you could do that anyway: any encoded video, if it were output as a TV signal, would have associated blanking, whether it contained captions or not.

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  • These are SD files. I.e Eia 608. You can read more here en.m.wikipedia.org/wiki/EIA-608
    – Johan Skaneby
    Commented Aug 9, 2015 at 14:01
  • You can read about EIA 608 here en.m.wikipedia.org/wiki/EIA-608
    – Johan Skaneby
    Commented Aug 9, 2015 at 14:03
  • So back to the original question - how to detect the presence of these lines? which tool?
    – Johan Skaneby
    Commented Aug 9, 2015 at 14:04
  • @JohanSkaneby Your question is about lines and frame size which are the wrong questions. These lines do not exist as video and do not affect the frame size. Only the data carried in those lines is stored in the container, alongside the video. Google "LXF VBI data" and you'll find pointers to tools that can find and read this data. It's a question of opening the file and scanning for headers.
    – Jim Mack
    Commented Aug 9, 2015 at 15:50
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    @JohanSkaneby Lines 21 & 22 are not considered part of active video and are not usually digitized. If they contain data it can be extracted and encoded as a separate stream. I had no difficulty locating tools via Google to examine LXF VBI streams, so yes, Google is your friend.
    – Jim Mack
    Commented Aug 9, 2015 at 17:36

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