[FFmpeg-user] problems with IPB Frames

[Guido Holz]

I tried now to get from my first cut-out all-I-Frames with the option "-g
1" like

ffmpeg.exe -ss 00:07:12.0 -i 00005.MTS -vf yadif=1 -r 25 -g 1 -t 00:00:20.0
-an -y tmp.mp4

When I do this

ffmpeg.exe -i tmp.mp4 -ss 00:00:04.0 -t 00:00:12.0 -y out.mp4

should I get normaly  a piece of footage beginning with an I-Frame, right?

So I would like to cut only out a piece of footage from a given big video
and I don't no realy how to get this

thansk for help



2014-01-28 Henk D. Schoneveld <belcampo at zonnet.nl>

>
> On 28 Jan 2014, at 16:03, Guido Holz <guido.holz at googlemail.com> wrote:
>
> > The job is to cut quikly out a piece from a big videostream (MTS) and to
> > stitch this piece with others together. The problem is, that I have many
> > times no I-frame as my first frame what means that I have some artifacts
> at
> > the beginning.
> >
> > first I cut quick a bigger piece out of the big stream.
> >
> > \>ffmpeg.exe -ss 00:07:12.0 -i 00005.MTS -vf yadif=1 -r 25 -t 00:00:20.0
> > -an -y tmp.mp4
> >
> > after I let run the video 4 seconds to cut after 4 seconds 12 seconds out
> > of the video (to catch an I-Frame for getting a smooth start of the
> video)
> >
> > \>ffmpeg.exe -i tmp.mp4 -ss 00:00:04.0 -t 00:00:12.0 -y out.mp4
> >
> > I need to convert from mp4 to ts because after I have to concatenate the
> > videos together
> >
> > \>ffmpeg.exe -i out.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts -y
> out.ts
> >
> > \>ffmpeg -i "concat:out.ts|out.ts" -i  a_sound_file.aac -c copy -bsf:a
> > aac_adtstoasc -y finish.mp4
> What you basically do is 'copying' chunks of a file. Without reencoding
> you'll always have these hit/miss situations, unless the source is
> all-i-frames.
> >
> > the  ouptut of the source-video is
> >
> > ffmpeg.exe -i 00005.MTS
> > ffmpeg version N-60202-g6369766 Copyright (c) 2000-2014 the FFmpeg
> > developers
> >  built on Jan 27 2014 02:02:32 with gcc 4.8.2 (GCC)
> >  configuration: --enable-gpl --enable-version3 --disable-w32threads
> > --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
> > --enable-gnutls --enable-iconv --enable-libass --enable-libbluray
> > --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc
> > --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
> > --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus
> > --enable-librtmp --enable-libschroedinger --enable-libsoxr
> > --enable-libspeex --enable-libtheora --enable-libtwolame
> > --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc
> > --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264
> > --enable-libxavs --enable-libxvid --enable-zlib
> >  libavutil      52. 63.100 / 52. 63.100
> >  libavcodec     55. 49.100 / 55. 49.100
> >  libavformat    55. 26.100 / 55. 26.100
> >  libavdevice    55.  5.102 / 55.  5.102
> >  libavfilter     4.  1.101 /  4.  1.101
> >  libswscale      2.  5.101 /  2.  5.101
> >  libswresample   0. 17.104 /  0. 17.104
> >  libpostproc    52.  3.100 / 52.  3.100
> > Input #0, mpegts, from '00005.MTS':
> >  Duration: 00:16:31.57, start: 4961.872000, bitrate: 17147 kb/s
> >  Program 1
> >    Stream #0:0[0x1011]: Video: h264 (High) (HDMV / 0x564D4448), yuv420p,
> > 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
> >    Stream #0:1[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo,
> > fltp, 256 kb/s
> >    Stream #0:2[0x1200]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] /
> > 0x0090), 1920x1080
> > At least one output file must be specified
> >
> >
> > what can I do to get no artifacts?
> >
> > --
> > _______________________________________________
> > ffmpeg-user mailing list
> > ffmpeg-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
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>



-- 

Guido Holz
managing director

www.sportograf.com :: photography for the love of sport

Sportograf GmbH & Co. KG
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mail:     guido at sportograf.com

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