# ==========================================
# Einstellungen
# ==========================================

$FFmpegExe = "C:\PortableApps\LIVE\ffmpeg.exe"

$Url = "http://zdf-hls-15.akamaized.net/hls/live/2016498/de/high/master.m3u8"

$TargetFolder = "D:\Downloads_ZDF"

# ==========================================
# Zielordner anlegen
# ==========================================

if (-not (Test-Path $TargetFolder)) {
    New-Item -ItemType Directory -Path $TargetFolder | Out-Null
}

# ==========================================
# Wie weit zurück?
# ==========================================

$BackTime = Read-Host "Wie weit zurueck? (hh:mm)"

try {
    $tsBack = [TimeSpan]::Parse($BackTime)
}
catch {
    Write-Host ""
    Write-Host "Fehler: Ungueltiges Format!"
    Write-Host "Beispiel: 01:30 = 1 Stunde 30 Minuten"
    Pause
    exit
}

# ==========================================
# Aufnahmedauer
# ==========================================

$Duration = Read-Host "Aufnahmedauer? (hh:mm)"

try {
    $tsDuration = [TimeSpan]::Parse($Duration)
}
catch {
    Write-Host ""
    Write-Host "Fehler: Ungueltiges Format!"
    Write-Host "Beispiel: 00:45 = 45 Minuten"
    Pause
    exit
}

# ==========================================
# Berechnungen
# ==========================================

$BackSeconds = [int]$tsBack.TotalSeconds
$DurationSeconds = [int]$tsDuration.TotalSeconds

# Maximal 3 Stunden Timeshift
if ($BackSeconds -gt 10800) {
    Write-Host ""
    Write-Host "Fehler: Maximal 3 Stunden Ruecksprung moeglich!"
    Pause
    exit
}

# HLS-Segmente sind 2 Sekunden lang
$SegmentsBack = [math]::Round($BackSeconds / 2)

# ==========================================
# Ausgabedatei erzeugen
# ==========================================

$Timestamp = Get-Date -Format "yyyy-MM-dd_HH-mm-ss"

$OutputFile = Join-Path `
    $TargetFolder `
    "ZDF_$Timestamp.mp4"

# ==========================================
# Informationen anzeigen
# ==========================================

Write-Host ""
Write-Host "========================================="
Write-Host "ZDF-Download wird gestartet"
Write-Host "========================================="
Write-Host "Zurueckspringen : $BackTime"
Write-Host "Aufnahmedauer   : $Duration"
Write-Host "Segmente        : $SegmentsBack"
Write-Host "Ausgabedatei    : $OutputFile"
Write-Host "========================================="
Write-Host ""

# ==========================================
# FFmpeg starten
# ==========================================

& $FFmpegExe `
    -live_start_index -$SegmentsBack `
    -i $Url `
    -t $DurationSeconds `
    -c copy `
    $OutputFile

# ==========================================
# Ende
# ==========================================

Write-Host ""
Write-Host "Download abgeschlossen."
Pause