[FFmpeg-user] Why are half the frames "duplicate" ?
Carl Eugen Hoyos
ceffmpeg at gmail.com
Sun Sep 30 21:58:49 EEST 2018
2018-09-30 17:21 GMT+02:00, sean darcy <seandarcy2 at gmail.com>:
> On 9/30/18 10:45 AM, sean darcy wrote:
>> 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.
This imo indicates that the command line is correct.
>> What did you see in the idet output that told you that the progressive
>> original (~24fps, correct ? ) had been telecined ?
I saw that it was not telecined (since all frames are progressive).
Therefore the only explanation that made sense was soft-telecine:
The actual framerate was always 24000/1001 but since old American
televisions required 30000/1001, the stream contains information
that frames have to be duplicated (what FFmpeg did originally).
Maybe unrelated:
Note that FFmpeg's mpeg-ps muxer is unable to add this information
to its output streams, MEncoder can do it.
> I've been googling soft telecine. Some have suggested using "-re"
> as the frame rate. Why would 24000/1001 be preferred ?
That does not sound correct, "-re" allows FFmpeg to encode in
real-time (instead of faster), it should not change the output frame
rate. Does it?
Carl Eugen
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