==================
Tile videos README
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:Authors:
    Desai Fan (2016-03)

:Version: 1.1

Introduction:
    This python program is used for combine multiple videos into a single tiled video, each of them with a time offset (delay).

Prerequisites:
    It requires OpenCV for python, numpy, ffmpeg and sox as prerequisites. 
    The python version is 2.7. The system is Mac OS X.

How to install these prerequisites?
    1. Install homebrew:
        /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
    2. Install python:
        brew install python
    2. Install OpenCV and setting up in python. You might find this web page helpful:
        https://jjyap.wordpress.com/2014/05/24/installing-opencv-2-4-9-on-mac-osx-with-python-support/
    3. Install numpy:
        pip install numpy
    4. Install ffmpeg:
        brew install ffmpeg
    5. Install sox:
        brew install sox
    Note you might need to add "sudo" as a prefix to your command in case you encounter a "Permission denied" failure.


Usage:

Command line:
    python tile_videos.py [config.txt] [output_video.mp4]

Format of configuration file:
    [video_0.mp4] [start_time_in_seconds] [end_time_in_seconds] [offset_in_seconds]
    [video_1.mp4] [start_time_in_seconds] [end_time_in_seconds] [offset_in_seconds]
    [video_2.mp4] [start_time_in_seconds] [end_time_in_seconds] [offset_in_seconds]
    ...

Example:
    0.mp4 0 40 12.301
    1.mp4 0 38 23.320
    2.mp4 0 27 0.351
    3.mp4 0 14 6.852
    4.mp4 0 15 12.202
    5.mp4 0 13 2.203
    6.mp4 0 15 2.323
    7.mp4 0 13 3.302
    8.mp4 0 25 13.302

Note:
    1. At least two videos and at most nine videos are allowed.
    2. start time means the starting point you want of the video.
    3. Similarly, end time means the ending point you want of the video. For example, if you like the whole video to be included, the start time would be 0 and the end time would be the duration of this video.
    4. Offset is the delay time specified for each of the video. You could have all of them non-zero, which would make the final video start with a few empty frames. Or, you could have only one of videos with an offset zero. In that case, only that video will play at the very beginning.