On Tue, 11 May 2004, Jonathan Woithe wrote:
> Correct. mpeg2enc claimed the input was bottom-first so I used the -z flag
> to override this. I was not aware (until you mentioned it) that DV is
> exclusively bottom first, but that at least means the "bottom first" input
Oh, I thought everyone knew that DV was bottom first only ;)
What's curious, to me at least, is that very little else that I've
seen is bottom first - the DVDs I've looked at have been top field
first (as is the TV broadcasts I've captured the MPEG-TS data from).
> > Check cinelerra --- see what it says about your video's field order. (If
>
> Ok, another thing to look into once I have the time. I'm not sure cinelerra
> provides this kind of info on the input stream - I might have to put in a
It could be that Cinelerra is getting the field order reversed by
getting the field buffers swapped around.
> Is there a way of telling how a DVD has been encoded in terms of field
> order?
For that I use a program called "dvdview" against the decrypted
.vob file. At log level 3 (-v 3) you get info like this:
GOP-Header:
Timecode: 0:00:00.00
closed GOP: true
broken link: false
Picture-Header-PTS: 53003
PictureHeader:
temporal reference: 0
picture_coding_type: I
vbv_delay: 65535
fullpel forward mv: false
fullpel backward mv: false
fcode[0][0] (fw/h): 15
fcode[0][1] (fw/v): 15
fcode[1][0] (bw/h): 15
fcode[1][1] (bw/v): 15
intra dc precision: 10
picture structure: frame picture
top field first: false
frame pred frame dct: false
concealment mvs: false
q-scale type: 1
intra vlc format: 1
alternate scan: true
repeat first field: false
chroma420type(obsolet):0
progressive frame: false
Which says "top field first false" (meaning bottom field first ;)).
That's from a .mpg file I created from a DV capture, so bottom first
is correct.
http://rachmaninoff.informatik.uni-mannheim.de/dvdview/
but the site seems down at the moment. At higher levels even more
information about a MPEG stream can be obtained - useful tool to have
around.
Cheers,
Steven Schultz
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