Fix -Frames negative range calculation to extract last N frames correctly (off-by-one error), add validation to reject invalid '-%' and '-0' formats with exit code 1, change '%' alone to extract single last frame instead of range, remove duplicate last frame from PNG sequence concat list, update Get-LastFrame.ps1 and Get-Frame.ps1 to clamp out-of-range frame indices instead of erroring and improve error messages with inline stderr output, add -y flag and -- separator to ffprobe calls, replace deprecated

Clone-Video.ps1

@@ -36,7 +36,7 @@
     - start-end: Extract frames from start to end (e.g., "100-200")
     - positive_number: Extract frames from 0 to that number (e.g., "50")
     - -negative_number: Extract last N frames (e.g., "-10")
-    - %: Represents the last frame index. Can be used alone or in ranges (e.g., "%", "10-%", "-%")
+    - %: Represents the last frame index. Can be used alone or in ranges (e.g., "%", "10-%")
     - all: Extract all frames (same as "0-%")
 .PARAMETER Sequence
     Path to PNG file for extracted frame. Can be absolute or relative to current directory. .png extension is added if not provided. If EndFrame is -1, extracts the last frame and excludes it from the cloned video. If EndFrame is not -1, extracts the frame at EndFrame index and excludes it from the cloned video.
@@ -228,6 +228,14 @@ if (-not [string]::IsNullOrWhiteSpace($Frames)) {
         Write-Error '-Frames cannot be used together with -StartFrame, -EndFrame, or -Sequence'
         exit 1
     }
+    if ($Frames -match '^-.*%') {
+        Write-Error "Invalid Frames format '$Frames': '-%' is not supported. Use '%' for the last frame, or -N for the last N frames."
+        exit 1
+    }
+    if ($Frames -match '^-0+$') {
+        Write-Error "Invalid Frames format '$Frames': a negative count must be at least 1. Use -1 for the last frame."
+        exit 1
+    }
 }
 
 $AudioPath = $null
@@ -478,13 +486,13 @@ if (Test-Path -LiteralPath $SourcePath -PathType Container) {
     $maxPngIndex = $pngFiles.Count - 1
 
     if (-not [string]::IsNullOrWhiteSpace($Frames)) {
-        $framesPattern = $Frames -replace '%', $maxPngIndex
+        $framesPattern = if ($Frames -eq '%') { "$maxPngIndex-$maxPngIndex" } else { $Frames -replace '%', $maxPngIndex }
         if ($framesPattern -ieq 'all') { $framesPattern = "0-$maxPngIndex" }
         if ($framesPattern -match '^(\d+)-(\d+)$') {
             $StartFrame = [int]$Matches[1]
             $EndFrame = [int]$Matches[2]
         } elseif ($framesPattern -match '^-(\d+)$') {
-            $StartFrame = [Math]::Max(0, $maxPngIndex - [int]$Matches[1])
+            $StartFrame = [Math]::Max(0, $maxPngIndex - [int]$Matches[1] + 1)
             $EndFrame = $maxPngIndex
         } elseif ($framesPattern -match '^\d+$') {
             $StartFrame = 0
@@ -601,7 +609,6 @@ if (Test-Path -LiteralPath $SourcePath -PathType Container) {
             $concatLines += "file '$pfPath'"
             $concatLines += "duration $frameDuration"
         }
-        $concatLines += "file '$($pngFiles[-1].FullName.Replace('\', '/'))'"
         [System.IO.File]::WriteAllLines($concatTempFile, $concatLines, [System.Text.UTF8Encoding]::new($false))
 
         $seqFfmpegArgs = @(
@@ -718,13 +725,13 @@ $totalFramesInt = [int]$totalFrames
 $maxFrameIndex = $totalFramesInt - 1
 
 if (-not [string]::IsNullOrWhiteSpace($Frames)) {
-    $framesPattern = $Frames -replace '%', $maxFrameIndex
+    $framesPattern = if ($Frames -eq '%') { "$maxFrameIndex-$maxFrameIndex" } else { $Frames -replace '%', $maxFrameIndex }
     if ($framesPattern -ieq 'all') { $framesPattern = "0-$maxFrameIndex" }
     if ($framesPattern -match '^(\d+)-(\d+)$') {
         $StartFrame = [int]$Matches[1]
         $EndFrame = [int]$Matches[2]
     } elseif ($framesPattern -match '^-(\d+)$') {
-        $StartFrame = [Math]::Max(0, $maxFrameIndex - [int]$Matches[1])
+        $StartFrame = [Math]::Max(0, $maxFrameIndex - [int]$Matches[1] + 1)
         $EndFrame = $maxFrameIndex
     } elseif ($framesPattern -match '^\d+$') {
         $StartFrame = 0