On Sunday 31 December 2006 04:02, Andy Walls wrote:
> > Can someone make the following available for downloading:
> >
> > I need two NTSC captures from a movie (NOT a 'made for TV' movie
> > but a 'real' movie that was made for movie theatres). I think that
> > it is best that it is from a recent movie (say from the last 3-4
> > years).
> >
> > First run 'v4l2-ctl -c video_pulldown=0'. Then make the first
> > capture: the first capture should be about a minute and captured
> > with a plain 'cat /dev/video0 >1.mpg'. To make the second capture
> > first issue this command: 'v4l2-ctl -c video_pulldown=1', then
> > start capturing another minute with 'cat /dev/video0 >2.mpg'.
> >
> > Capture from a decent quality channel with a clear picture and
> > should be 720x480 (so no scaling).
> >
> > I want to compare two such streams to see if the 3:2 pulldown
> > control really works (and if so, if it does what I think it does).
> >
> > But since this control is NTSC-only I need some help here!
> >
> > Of course, if you have two cards in the same box with equally good
> > picture quality, then it would be even better if each records the
> > same picture but with different video_pulldown settings. Although
> > for the purposes of this test both cards should have the same
> > digitizer (saa7115 vs cx2584x). So either both cards are a
> > PVR250/350 or both are a PVR150/500.
>
> Well, I've got 2 1 minute captures from LOTR and 2 48 second captures
> from Star Wars Episode 1. I used a Panasonic DVD player feeding
> video into Composite Input 2 of my PVR-150 MCE.
>
> The files are huge:
>
> [EMAIL PROTECTED] ~]$ ls -altr *mpg
> -rw-rw-r-- 1 andy andy 39092160 Dec 24 13:46 pulldown-0.mpg
> -rw-rw-r-- 1 andy andy 39409600 Dec 24 13:47 pulldown-1.mpg
> -rw-rw-r-- 1 andy andy 49358784 Dec 24 14:02 lotr-0.mpg
> -rw-rw-r-- 1 andy andy 49721280 Dec 24 14:03 lotr-1.mpg
>
> so my 33.6 kbps dial-up upload to somewhere is probably not an
> option. Plus I'm not sure this would count as fair use under US
> Copyright law (I prefer to stay well beyond reproach on legal
> issues...)
>
> So what specifically are you looking for in these files? Maybe I
> could analyze them for you. I assume you're looking for evidence of
> inverse telecine as Conexants brochure on the MPEG encoder touts.
>
> Here are some observations:
>
> 1. Computer generated stuff doesn't gzip well, and captures with
> video_pulldown = 1 compress better (indicating slightly greater
> redundancy):
>
> 1 minute from the middle of the incredibles
> [EMAIL PROTECTED] ~]$ gzip -9 -v pulldown-0.mpg pulldown-1.mpg
> pulldown-0.mpg: 6.0% -- replaced with pulldown-0.mpg.gz
> pulldown-1.mpg: 6.4% -- replaced with pulldown-1.mpg.gz
>
> 48 seconds from the beginning of Star Wars Episode 1
> [EMAIL PROTECTED] ~]$ gzip -v -9 pulldown-*.mpg
> pulldown-0.mpg: 13.7% -- replaced with pulldown-0.mpg.gz
> pulldown-1.mpg: 14.1% -- replaced with pulldown-1.mpg.gz
>
> 1 minute from the beginning of the The Fellowship of the Rings
> [EMAIL PROTECTED] ~]$ gzip -v -9 lotr-*
> lotr-0.mpg: 70.9% -- replaced with lotr-0.mpg.gz
> lotr-1.mpg: 71.2% -- replaced with lotr-1.mpg.gz
>
>
> 2. The ivtv driver outputs stuff on 0x800 byte boundaries, making
> quick and dirty frame counts pretty simple:
>
> [EMAIL PROTECTED] ~]$ xxd -c 32 lotr-0.mpg | grep '[08]00: ' | grep -v
> '01e0 07ec' | grep '0000 01e0' | wc -l
> 1807
> [EMAIL PROTECTED] ~]$ xxd -c 32 lotr-1.mpg | grep '[08]00: ' | grep -v
> '01e0 07ec' | grep '0000 01e0' | wc -l
> 1816
>
> But for reference here's what mpeg2dec says:
>
> [EMAIL PROTECTED] ~]$ mpeg2dec -o null -s lotr-0.mpg
> mpeg2dec-0.4.0 - by Michel Lespinasse <[EMAIL PROTECTED]> and Aaron
> Holtzman
> 1689 frames in 5.98 sec (282.44 fps), 148 last 0.50 sec (296.00 fps)
> 1811 frames decoded in 6.38 seconds (283.86 fps)
>
> [EMAIL PROTECTED] ~]$ mpeg2dec -o null -s lotr-1.mpg
> mpeg2dec-0.4.0 - by Michel Lespinasse <[EMAIL PROTECTED]> and Aaron
> Holtzman
> 1796 frames in 5.46 sec (328.94 fps), 152 last 0.50 sec (304.00 fps)
> 1824 frames decoded in 5.56 seconds (328.06 fps)
>
>
>
> 3. "cat /dev/video | mplayer -" with the intro to LOTR seems to tax
> my system noticeably more with video_pulldown = 1 than with
> video_pulldown = 0
>
>
> 4. If video_pulldown = 0 really means inverse telecine enabled, the
> MPEG decoder gets it wrong for a few frames at the beginning of the
> LOTR, where I can see a horizontal "comb" of lines in the fire to the
> right of the cup of molten gold.
I have had confirmation that the pulldown isn't implemented in the
firmware. It may have been a feature of (very) old firmwares but if so
it was removed in later firmwares.
Thanks for testing!
Hans
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