[FFmpeg-user] Various problems exchanging end of video

[Hauke Westemeier]

Hi,

I'm using ffmpeg version N-81664-g6f062eb with Windows 8.1 and have
some problems. I want to replace the end of a short video by an image
and avoid recoding.

Step 0) Some details of the initial video:

ffmpeg.exe -i original.mp4

  Duration: 00:00:47.50, start: 0.000000, bitrate: 97 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
480x270 [SAR 1:1 DAR 16:9], 97 kb/s, 10 fps, 20 tbr, 10240 tbn, 40 tbc
(default)

I've read a little about fps tbr, tbn, tbc but I'm not really sure why
all four values are different from each other but for now accepted
that this is the case (due to interlacing?)


Step 1) Remove end

ffmpeg.exe -i original.mp4 -codec copy -ss 00:00:00 -to 00:00:43 cut.mp4

warn
Using AVStream.codec to pass codec parameters to muxers is deprecated,
use AVStream.codecpar instead.
but cut.mp4 seems to be playing fine and as expected the old end is
removed.

Interestingly the frame rate is slightly changed (due to rounding
effects?)

ffmpeg.exe -i cut.mp4

  Duration: 00:00:43.00, start: 0.000000, bitrate: 107 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
480x270 [SAR 1:1 DAR 16:9], 106 kb/s, 9.81 fps, 20 tbr, 10240 tbn, 40
tbc (default)


Step 2) Create new end based on an image

ffmpeg.exe -loop 1 -i newEnd.png  -t 5 -r 9.81 -c:v libx264 -pix_fmt
yuv420p newEnd.mp4

gives the desired video of this image

ffmpeg.exe -i newEnd.mp4

 Duration: 00:00:05.10, start: 0.000000, bitrate: 8 kb/s
   Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
480x270 [SAR 1:1 DAR 16:9], 5 kb/s, 9.81 fps, 9.81 tbr, 15696 tbn,
19.62 tbc (default)


Step 3) Concat the cutted video and new end to get final result

ffmpeg.exe -f concat -i videos.txt -codec copy -r 9.81 finalresult.mp4
with videos.txt containing:
file cut.mp4
file newEnd.mp4

Instead of 43s + 5s =48 s the resulting video is significantly longer
as the fps decreased again :-/

ffmpeg.exe -i finalresult.mp4
  Duration: 00:01:13.41, start: 0.000000, bitrate: 63 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
480x270 [SAR 1:1 DAR 16:9], 62 kb/s, 6.43 fps, 20 tbr, 15696 tbn, 40 tbc


If I use VLC to watch the resulting video the newEnd is not shown but
the video freezes at the end. I tested various approaches (with and
without "-r" option, providing length in the videos.txt, ...) but I
don't get it to work. Help is highly appreciated, already many thanks!!

Hauke