[FFmpeg-user] Missing frames when using ffconcat

[Thomas Howe]

I've since found and started using another solution - changing the way I
generate the scripts to use image2pipe instead of ffconcat.

The input frames are drawings of numbers, to help with troubleshooting, and
I don't know how to make ffmpeg do that. I'm not sure I'd suggest it as a
feature because imagemagick has it covered pretty well anyway. I could
upload the frames if that would help?

Attached is a corrected script, but nothing that affects what it does.

Below is the output of the problematic command.

Tom


$ ffmpeg -i test-video/list.ffconcat -vf fps=50 -c:v libvpx-vp9 -pix_fmt
yuv420p test-video/video.webm
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static
--disable-stripping --enable-avisynth --enable-avresample
--enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl
--enable-ladspa --enable-libass --enable-libbluray --enable-libfreetype
--enable-libfribidi --enable-libgsm --enable-libiec61883
--enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb
--enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus
--enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh
--enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis
--enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxcb --enable-libxvid --enable-shared --enable-version3
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, concat, from 'test-video/list.ffconcat':
  Duration: 00:00:10.00, start: 0.000000, bitrate: 8 kb/s
    Stream #0:0: Video: png, ya8(pc), 300x50, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (png (native) -> vp9 (libvpx-vp9))
Press [q] to stop, [?] for help
[libvpx-vp9 @ 0x3dee226fc0] v1.6.1
Output #0, webm, to 'test-video/video.webm':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Video: vp9 (libvpx-vp9), yuv420p, 300x50, q=-1--1, 200
kb/s, 50 fps, 1k tbn, 50 tbc
    Metadata:
      encoder         : Lavc57.107.100 libvpx-vp9
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
[out_0_0 @ 0x3dee239300] 100 buffers queued in out_0_0, something may be
wrong.
frame=  186 fps=0.0 q=0.0 size=      17kB time=00:00:03.22 bitrate=
42.9kbits/sframe=  340 fps=339 q=0.0 size=      49kB time=00:00:06.30
bitrate=  63.3kbits/sframe=  402 fps=305 q=0.0 Lsize=      97kB
time=00:00:08.02 bitrate=  98.7kbits/s speed=6.08x
video:93kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 3.450979%


On 21 October 2017 at 19:59, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 2017-10-18 2:12 GMT+02:00 Thomas Howe <tho7maspenguin at gmail.com>:
>
> > I'm working on a project that requires ff.concat files to be interpreted
> > accurately, but every other frame in my 50fps project goes missing (is
> > filled in with the previous frame instead). I think this might be related
> > to ffmpeg's default 25fps, but I can't find the command to make it work
> > properly.
> >
> > Here's the command I'm using:
> > ffmpeg -i test-video/list.ffconcat -vf fps=50 -c:v libvpx-vp9 -pix_fmt
> > yuv420p test-video/video.webm
>
> Complete, uncut console output missing.
>
> > And attached is a script (requiring imagemagick to run)
>
> (Is there a reason FFmpeg cannot generate the input frames?
> Maybe a missing feature?)
>
> Carl Eugen
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