[FFmpeg-user] Why are half the frames "duplicate" ?

[sean darcy]

On 9/29/18 5:15 PM, Carl Eugen Hoyos wrote:
> 2018-09-29 22:46 GMT+02:00, sean darcy <seandarcy2 at gmail.com>:
>> On 9/28/18 7:29 PM, Carl Eugen Hoyos wrote:
>>> 2018-09-28 20:58 GMT+02:00, sean darcy <seandarcy2 at gmail.com>:
>>>
>>>> Also, I used ffprobe:
>>>>
>>>> ffprobe -show_frames -select_streams v -i in.mpg  2>&1 | grep -c
>>>> interlaced_frame=1
>>>> 2052
>>>> ffprobe -show_frames -select_streams v -i in.mpg  2>&1 | grep -c
>>>> interlaced_frame=0
>>>> 30347
>>>>
>>>> This means there are at least some interlaced frames
>>>
>>> No, unfortunately ffprobe cannot tell you (the information above
>>> is mostly unrelated to the question if the content is interlaced,
>>> telecined or progressive).
>>>
>>> Either use the idet filter or do a visual inspection.
>>>
>>> Carl Eugen
>>> _______________________________________________
>>
>> Never used idet filter before, so don't know how to make use of the info.
>>
>> ffmpeg -vf idet -frames:v 5000 -an -f rawvideo -y /dev/null -i  in.mpg
>> ffmpeg version git-snapshot-20180928-RPMFusion Copyright (c) 2000-2018
>> the FFmpeg developers
>>     built with gcc 8 (GCC)
>>     configuration: --prefix=/usr --bindir=/usr/bin
>> --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg
>> --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64
>> --optflags='-O2 -ffast-math -march=native -ftree-vectorize
>> -fomit-frame-pointer -pipe -fPIC' --enable-bzlib --disable-crystalhd
>> --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls
>> --enable-ladspa --enable-libass --enable-libbluray --enable-libcdio
>> --enable-libfdk-aac --enable-nonfree --enable-indev=jack
>> --enable-libfreetype --enable-libfribidi --enable-libgsm
>> --enable-libmp3lame --enable-openal --enable-opencl --disable-libopencv
>> --enable-opengl --enable-libopenjpeg --enable-libopus --enable-libpulse
>> --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis
>> --enable-libv4l2 --enable-libvpx --enable-libwebp --enable-libx264
>> --enable-libx265 --enable-avfilter --enable-postproc --enable-pthreads
>> --disable-static --enable-shared --enable-gpl --enable-version3
>> --enable-nonfree --disable-debug --enable-stripping
>> --shlibdir=/usr/lib64 --enable-runtime-cpudetect
>>     libavutil      56. 19.101 / 56. 19.101
>>     libavcodec     58. 31.101 / 58. 31.101
>>     libavformat    58. 18.103 / 58. 18.103
>>     libavdevice    58.  4.104 / 58.  4.104
>>     libavfilter     7. 33.100 /  7. 33.100
>>     libswscale      5.  2.100 /  5.  2.100
>>     libswresample   3.  2.100 /  3.  2.100
>>     libpostproc    55.  2.100 / 55.  2.100
>> [mpeg2video @ 0x1eef200] Invalid frame dimensions 0x0.
>>       Last message repeated 10 times
>> Input #0, mpeg, from 'in.mpg':
>>     Duration: 26:09:34.50, start: 1305.384367, bitrate: 91 kb/s
>>       Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv,
>> progressive), 720x480 [SAR 8:9 DAR 4:3], Closed Captions, 29.97 fps,
>> 59.94 tbr, 90k tbn, 59.94 tbc
>>       Stream #0:1[0x81]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
>>       Stream #0:2[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
>>       Stream #0:3[0x1bf]: Data: dvd_nav_packet
>>       Stream #0:4[0x22]: Subtitle: dvd_subtitle
>>       Stream #0:5[0x21]: Subtitle: dvd_subtitle
>>       Stream #0:6[0x20]: Subtitle: dvd_subtitle
>> Stream mapping:
>>     Stream #0:0 -> #0:0 (mpeg2video (native) -> rawvideo (native))
>> Press [q] to stop, [?] for help
>> Output #0, rawvideo, to '/dev/null':
>>     Metadata:
>>       encoder         : Lavf58.18.103
>>       Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 720x480
>> [SAR 8:9 DAR 4:3], q=2-31, 124291 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc
>>       Metadata:
>>         encoder         : Lavc58.31.101 rawvideo
>> More than 1000 frames duplicated= 2191360kB time=00:02:24.44
>> bitrate=124280.6kbits/s dup=867 drop=0 speed=72.2x
>> frame= 5000 fps=2162 q=-0.0 Lsize= 2531250kB time=00:02:46.83
>> bitrate=124291.7kbits/s dup=1001 drop=0 speed=72.1x
>> video:2531250kB audio:0kB subtitle:0kB other streams:0kB global
>> headers:0kB muxing overhead: 0.000000%
>> [Parsed_idet_0 @ 0x21f7dc0] Repeated Fields: Neither:  4000 Top:     0
>> Bottom:     0
>> [Parsed_idet_0 @ 0x21f7dc0] Single frame detection: TFF:     0 BFF:
>> 0 Progressive:  3894 Undetermined:   106
>> [Parsed_idet_0 @ 0x21f7dc0] Multi frame detection: TFF:     0 BFF:     0
>> Progressive:  4000 Undetermined:     0
>>
>> As I read this, the idet filter only saw 4000 out of the 5000 frames, of
>> which 106 couldn't be classified. What about the 1001 duplicated frames ?
> 
> This indicates soft-telecine of progressive original.
> 
> Please test with output option "-r 24000/1001". If that
> leads to (many) duplicated and dropped frames, there
> are ways to work-around iirc.
> 
> Carl Eugen

You are the man !

Ran the entire clip at 24000/1001, only 11 duplicated frames.
What did you see in the idet output that told you that the progressive 
original (24fps, correct ? ) had been telecined ?