[FFmpeg-user] Mixed telecined non-telecined media to constant frame rate.

[Nicholas Robbins]

> On Tuesday, January 21, 2014 12:37 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> > Nicholas Robbins <nickrobbins <at> yahoo.com> writes:
> 
>>  Indeed if I don't put in any fps filter I see that I 
>>  have frames at the following pkt_pts's
>>  ...
>>  20020
>>  20053
>>  20087
>>  20120*
>>  20187
>>  20220
>>  20254
>>  20287*
>>  20354
> 
> I didn't look at the source but it doesn't seem absurd 
> to me (although probably buggy) that this is what 
> pullup produces (fieldmatch,decimate are worse imo 
> because they simply ignore the input timestamps).

Yeah, if the material was all telescened then, yes this would be perfect, a -r could fix the spacing. I suppose I want a "smooth pts" filter that would smooth out the pts of the frames. I don't know how this information is stored, if it was two arrays oldpts[i] and newpts[i] then something like 

newpts[i] = Average(oldpts[i-N+1] ... oldpts[i]) + (oldpts[i]-oldpts[i-N+1])/2 -1 works for some made up numbers. 

N would be something like 30 or so I suppose. You would need a smaller timebase for this to work. 

Is there a way to set the timebase ? I see at http://ffmpeg.org/ffmpeg-all.html#Codec-Options that there is a time_base option, but I can't figure out how to set it.


> Does it work better with mencoder -ofps 60 or do you 
> see the same issues?

Again, stranger and stranger. 

$mencoder  short.mkv -oac copy -vf pullup -ovc x264 -ofps 60000/1001 -o mencoder.mpg

produces a lot of this:

2 duplicate frame(s)!
Pos:  23.5s    782f (100%) 28.12fps Trem:   0min   3mb  A-V:0.003 [412:0]

1 duplicate frame(s)!
Pos:  23.5s    783f (100%) 28.14fps Trem:   0min   3mb  A-V:0.007 [412:0]

1 duplicate frame(s)!
Pos:  23.5s    784f (100%) 28.15fps Trem:   0min   3mb  A-V:0.010 [412:0]

1 duplicate frame(s)!
Pos:  23.5s    785f (100%) 28.18fps Trem:   0min   3mb  A-V:0.013 [412:0]

2 duplicate frame(s)!
Pos:  23.6s    787f (100%) 28.20fps Trem:   0min   3mb  A-V:0.003 [411:0]

1 duplicate frame(s)!
Pos:  23.6s    788f (100%) 28.20fps Trem:   0min   3mb  A-V:0.007 [411:0]

1 duplicate frame(s)!
Pos:  23.7s    789f (100%) 28.18fps Trem:   0min   3mb  A-V:0.010 [411:0]

1 duplicate frame(s)!
Pos:  23.7s    790f (100%) 28.21fps Trem:   0min   3mb  A-V:0.013 [411:0]

2 duplicate frame(s)!
Pos:  23.8s    792f (100%) 28.23fps Trem:   0min   3mb  A-V:0.003 [410:0]

in the telecined section.  ffprobe -show_streams -select_streams s -count_frames mencoder.mpg produces:

Input #0, avi, from 'mencoder.mpg':
  Metadata:
    encoder         : MEncoder SVN-r36370 (Gentoo)-4.7.3
  Duration: 00:00:36.04, start: 0.000000, bitrate: 1048 kb/s
    Stream #0:0: Video: h264 (High) (h264 / 0x34363268), yuv420p, 720x480 [SAR 427:360 DAR 427:240], SAR 4096:3453 DAR 2048:1151, 59.94 fps, 59.94 tbr, 59.94 tbn, 119.88 tbc
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 448 kb/s
[STREAM]
index=0
codec_name=h264
codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
profile=High
codec_type=video
codec_time_base=1001/120000
codec_tag_string=h264
codec_tag=0x34363268
width=720
height=480
has_b_frames=2
sample_aspect_ratio=4096:3453
display_aspect_ratio=2048:1151
pix_fmt=yuv420p
level=31
timecode=N/A
id=N/A
r_frame_rate=60000/1001
avg_frame_rate=60000/1001
time_base=1001/60000
start_pts=0
start_time=0.000000
duration_ts=2160
duration=36.036000
bit_rate=N/A
nb_frames=2160
nb_read_frames=1052
nb_read_packets=N/A
DISPOSITION:default=0
DISPOSITION:dub=0
DISPOSITION:original=0
DISPOSITION:comment=0
DISPOSITION:lyrics=0
DISPOSITION:karaoke=0
DISPOSITION:forced=0
DISPOSITION:hearing_impaired=0
DISPOSITION:visual_impaired=0
DISPOSITION:clean_effects=0
DISPOSITION:attached_pic=0
[/STREAM]

Finally 
$ ffprobe -show_frames -select_streams v mencoder.mpg | grep "dts=" | cut -d"=" -f2 > tc.txt

(all video frames have pkt_pts=N/A)

and then loading that into a spreadsheet and taking differences of squential frames  gives the following pattern in the originally 30fps section 1,2,2,2,2,1,2,2,2,2,1,2....

in the telescened section it produces this 1,2,3,3,1,2,3,3,1,2,3,3,...

looking at it with ffplay, I don't see any duplicated frames.