#!/bin/sh
#------------------------------------------------------------------------------
# =========                 |
# \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
#  \\    /   O peration     |
#   \\  /    A nd           | www.openfoam.com
#    \\/     M anipulation  |
#------------------------------------------------------------------------------
#     Copyright (C) 2015-2016 OpenFOAM Foundation
#     Copyright (C) 2018-2020 OpenCFD Ltd.
#------------------------------------------------------------------------------
# License
#     This file is part of OpenFOAM.
#
#     OpenFOAM is free software: you can redistribute it and/or modify it
#     under the terms of the GNU General Public License as published by
#     the Free Software Foundation, either version 3 of the License, or
#     (at your option) any later version.
#
#     OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
#     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
#     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
#     for more details.
#
#     You should have received a copy of the GNU General Public License
#     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
#
# Script
#     foamCreateVideo
#
# Description
#     Creates a video file from PNG images
#     - requires one of avconv, ffmpeg, mencoder
#
#------------------------------------------------------------------------------

# Input defaults
inputDir='.'
prefix='image.'
inputMask='%04d'    # (avconv only)
unset startNumber   # (avconv only)

# Output defaults
outputPrefix=video
outputFormat=mp4
frameRate=10
unset converter

#------------------------------------------------------------------------------
printHelp () {
    cat<<USAGE

Usage: ${0##*/} [OPTIONS] ...
options:
  -d | -dir <dir>       input directory with png images  (default: '.')
  -f | -fps <fps>       frames per second  (default: 10)
  -i | -image <name>    input image sequence prefix  (default: 'image.')
  -o | -out <name>      output video name  (default: 'video')
  -tool=NAME            Specify avconv, ffmpeg, mencoder...
  -mask <width>         avconv input mask width (default: 4)
  -start <frame>        avconv start frame number
  -webm                 WebM output video file format (avconv only)
  -h | -help            Print the usage

Creates a video file from a sequence of PNG images.
With the default prefix ('image.'), from image.0000.png, image.0001.png, ...
- The output format is MPEG4
- The output name (with mp4 format), is "video.mp4"
- By default the video codec is high resolution

MPEG4 output requires avconv, mencoder, ffmpeg, ...
WebM  output requires avconv.

By default will attempt avconv, ffmpeg, mencoder.
Use the -tool option to specify a particular converter.

USAGE
    exit 0  # A clean exit
}


# Report error and exit
die()
{
    exec 1>&2
    echo
    echo "Error encountered:"
    while [ "$#" -ge 1 ]; do echo "    $1"; shift; done
    echo
    echo "See '${0##*/} -help' for usage"
    echo
    exit 1
}

#-------------------------------------------------------------------------------

# Parse options
while [ "$#" -gt 0 ]
do
    case "$1" in
    -h | -help*)
        printHelp
        ;;

    -d | -dir)
        [ "$#" -ge 2 ] || die "'-dir' requires an argument"
        inputDir=$2
        shift
       ;;
    -f | -fps)
        [ "$#" -ge 2 ] || die "'-fps' requires an argument"
        frameRate=$2
        shift
        ;;
    -i | -image)
        [ "$#" -ge 2 ] || die "'-image' requires an argument"
        prefix=$2
        shift
        ;;
    -o | -out)
        [ "$#" -ge 2 ] || die "'-out' requires an argument"
        outputPrefix=$2
        shift
        ;;
    -mask)
        [ "$#" -ge 2 ] || die "'-mask' requires an argument"
        digits="$(( $2 + 0 ))"
        if [ "$digits" -gt 0 ]
        then
            inputMask="%0${digits}d"
            echo "using input mask $inputMask"
        else
            echo "input mask unchanged $inputMask"
        fi
        shift
        ;;
    -start)
        [ "$#" -ge 2 ] || die "'-start' requires an argument"
        startNumber="-start_number $2"
        shift
        ;;
    -webm)
        outputFormat=webm
        ;;
    -tool=*)
        converter="${1#*=}"
        [ -n "$converter" ] || die "Missing value for -tool= option"
        ;;
    -*)
        die "invalid option '$1'"
        ;;
    *)
        break
        ;;
    esac
    shift
done

#------------------------------------------------------------------------------
# Sanity checks

if [ "$outputFormat" = webm ]
then
    command -v avconv >/dev/null || \
        die "webm format requires avconv, which was not found."

elif [ -z "$converter" ]
then
    # No converter specified, go on discovery...
    for candiate in avconv mencoder ffmpeg
    do
        if command -v "$candiate" >/dev/null
        then
            converter="$candiate"
            break
        fi
    done

    [ -n "$converter" ] || \
        die "No suitable converter found (avconv, ffmpeg, mencoder)" \
            "Cannot create video."

else
    command -v "$converter" >/dev/null || \
        die "No converter found: '$converter'"
fi


#------------------------------------------------------------------------------
# Check if input files exist

nFiles="$(\ls $inputDir/$prefix*.png 2>/dev/null | wc -l)"

echo "=============="
echo "Output file:  $outputPrefix.$outputFormat"
echo "Input files:  $prefix*.png"
echo "Detected:     $nFiles files"
echo "=============="
if [ "$nFiles" = 0 ]
then
    echo "No input files found. Stopping"
    exit 1
fi


#------------------------------------------------------------------------------
# Conversion

if [ "$outputFormat" = webm ]
then
    echo "Creating video with avconv..."
    echo
    avconv \
        -framerate $frameRate $startNumber \
        -i "$inputDir/$prefix$inputMask.png" \
        -c:v libvpx -crf 15 -b:v 1M \
        "$outputPrefix.$outputFormat"

else

    # Dispatch
    case "$converter" in
    (avconv | */avconv)
        echo "Creating video with avconv ..."
        echo
        "$converter" \
            -framerate $frameRate $startNumber \
            -i "$inputDir/$prefix$inputMask.png" \
            -c:v libx264 -pix_fmt yuv420p \
            "$outputPrefix.$outputFormat"
        ;;

    (ffmpeg | */ffmpeg)
        echo "Creating video with ffmpeg ..."
        echo
        "$converter" \
            -r $frameRate \
            -i "$inputDir/$prefix$inputMask.png" \
            -vcodec libx264 -pix_fmt yuv420p \
            "$outputPrefix.$outputFormat"
        ;;

    (mencoder | */mencoder)
        echo "Creating video with mencoder ..."
        echo
        "$converter" \
            "mf://$inputDir/$prefix*.png" \
            -mf fps=$frameRate \
            -o "$outputPrefix.$outputFormat" \
            -ovc x264
        ;;

    (*)
        die "Unknown converter: '$converter'"
        ;;
    esac
fi

#------------------------------------------------------------------------------