[MEncoder-users] settings to convert ATSC HDTV 1080i30 to 720p24

[Justin Randall]

> The telecine flags allow you to effectively broadcast 24 fps. Some 1080i
> cable channels like HBO use the telecine flags correctly for filmed
> content. Unfortunately broadcast network distribution from the 1080i
> networks can't use these flags because the stations receive a high
> bitrate feed (24-45 Mbps) and reencode it into ATSC. Some stations have
> smart encoders that try very hard to match fields and mark them with the
> telecine flags when the reencode. They're not perfect so you'll see them
> switch back and forth.


This would explain why my recording of "Numb3rs" was switching back
and forth between progressive and interlaced. This is with MythTV but
I believe that their player is derived from MPlayer source.


Playing /var/tmp/1017_20061005195900_20061005203000.nuv.
TS file format detected.
DEMUX OPEN, AUDIO_ID: -1, VIDEO_ID: -1, SUBTITLE_ID: -2,
PROBING UP TO 2000000, PROG: 0
VIDEO MPEG2(pid=33)AUDIO A52(pid=36) NO SUBS (yet)! PROGRAM N. 1
Opened TS demuxer, audio: 2000(pid 36), video: 10000002(pid
33)...POS=564, PROBE=2000000
VIDEO: MPEG2 1920x1080 (aspect 3) 29.970 fps 65000.0 kbps (8125.0 kbyte/s)
<...>
A:23071.4 V:23071.7 A-V: -0.236 ct: -0.070 25/ 22 133% 35% 3.6% 6 0
demux_mpg: 24000/1001fps progressive NTSC content detected, switching framerate.
A:23074.3 V:23074.3 A-V: 0.035 ct: -0.287 91/ 88 54% 25% 2.0% 6 0
demux_mpg: 30000/1001fps NTSC content detected, switching framerate.
Warning! FPS changed 23.976 -> 29.970 (-5.994005) [4] 5% 2.0% 6 0
A:23076.7 V:23076.7 A-V: -0.007 ct: -0.238 165/157 43% 29% 1.7% 6 0
demux_mpg: 24000/1001fps progressive NTSC content detected, switching framerate.
A:23078.0 V:23077.9 A-V: 0.051 ct: -0.185 195/187 40% 27% 1.7% 6 0
demux_mpg: 30000/1001fps NTSC content detected, switching framerate.
Warning! FPS changed 23.976 -> 29.970 (-5.994005) [4] 7% 1.7% 6 0
A:23079.1 V:23079.1 A-V: 0.003 ct: -0.126 231/220 38% 30% 1.6% 6 0
demux_mpg: 24000/1001fps progressive NTSC content detected, switching framerate.
A:23082.5 V:23082.5 A-V: 0.035 ct: -0.004 316/304 37% 27% 1.9% 6 0
demux_mpg: 30000/1001fps NTSC content detected, switching framerate.


So for most of this feed I can recover progressive content using -vf
pullup,softskip and that works great, but there also seems to be
non-teleclined frames in a straight 2:2 interlace pattern at some
points.  I assume that these points are where the telecline flags got
screwed up, possibly where bit errors occurred, or where there was a
commercial.  Hmm interresting, this may be a good way to detect where
commercials start and end in the broadcast. It appears that the
majority of the commercials are a full interlace video while the
actual show is teleclined. Anyway, it's far easier to recover the
24fps film from 720p content then it is with 1080i content.


Does anybody know if there is a way for MPlayer to detect the PPPII
PPPII format or if there is no telecline pattern in the source?  That
way I could write a script to determine if my encode needs to be
inverse teleclined back down to film (Lost, Heros, sitcoms, etc.) or
if I need to bob it up to ~60fps progressive (Leno, Conan, news etc.)
Thanks for your replies everyone.