Add -Clip parameter to remove letterboxing from 2-video comparisons by matching output height to scaled source height

Compare-Videos.ps1

@@ -53,6 +53,14 @@
 .PARAMETER In4K
     Generate comparison video in 4K UHD (3840x2160) resolution instead of 1K HD (1920x1080).
 
+.PARAMETER Clip
+    Reduces the output height to match the actual scaled height of the sources, removing
+    the top/bottom black letterbox padding. Only applies when exactly 2 source videos are
+    provided; ignored otherwise.
+
+    Example: two 1280x720 (16:9) sources rendered at 1K HD become 1920x540 instead of
+    1920x1080. The same pair rendered with -In4K becomes 3840x1080 instead of 3840x2160.
+
 .EXAMPLE
     .\Compare-Videos.ps1 -S1 original.mp4 -S2 enhanced.mp4 -Output comparison.mp4
 
@@ -77,6 +85,11 @@
     .\Compare-Videos.ps1 -S1 original.mp4 -S2 enhanced.mp4 -Output comparison_4k.mp4 -In4K
 
     Compare two videos in 4K UHD (3840x2160) resolution.
+
+.EXAMPLE
+    .\Compare-Videos.ps1 -S1 a_720p.mp4 -S2 b_720p.mp4 -Output side-by-side.mp4 -Clip
+
+    Compare two 720p (1280x720) videos with no top/bottom letterboxing: output is 1920x540.
 #>
 [CmdletBinding(SupportsShouldProcess)]
 param(
@@ -97,7 +110,9 @@ param(
     
     [switch]$NoAudio,
     
-    [switch]$In4K
+    [switch]$In4K,
+
+    [switch]$Clip
 )
 
 $ErrorActionPreference = "Stop"
@@ -132,6 +147,11 @@ $videoCount = 2
 if ($S4) { $videoCount = 4 }
 elseif ($S3) { $videoCount = 3 }
 
+if ($Clip -and $videoCount -ne 2) {
+    Write-Warning "-Clip is only supported with exactly 2 source videos; ignoring."
+    $Clip = $false
+}
+
 # --- Detect orientation of S1 ---
 
 Write-Host "Detecting orientation of S1..." -ForegroundColor Cyan
@@ -165,6 +185,42 @@ if ($isPortrait) {
     Write-Host "Landscape mode detected (${width}x${height}) - Output: $resolutionLabel" -ForegroundColor Green
 }
 
+# --- Clip mode: shrink output height to the actual scaled height of the sources ---
+if ($Clip) {
+    Write-Host "Probing S2 dimensions for -Clip..." -ForegroundColor Cyan
+    $probeOutput2 = & ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=p=0 $S2 2>&1
+    if ($LASTEXITCODE -ne 0) {
+        Write-Error "Failed to probe video dimensions for S2: $probeOutput2"
+        exit 1
+    }
+    $dim2 = $probeOutput2 -split ','
+    $w2 = [int]$dim2[0]
+    $h2 = [int]$dim2[1]
+
+    # Per-source cell width matches the 2-video branches below.
+    if ($isPortrait) {
+        $clipCellWidth = [int]($outputWidth * 0.6333 / 2)
+    } else {
+        $clipCellWidth = [int]($outputWidth / 2)
+    }
+
+    # Height each source would naturally scale to inside its cell when fitted by width
+    # (force_original_aspect_ratio=decrease). Take the larger of the two so neither
+    # source loses content; cap at the original output height.
+    $h1Scaled = [int][Math]::Floor($clipCellWidth * $height / $width)
+    $h2Scaled = [int][Math]::Floor($clipCellWidth * $h2 / $w2)
+    $clippedHeight = [Math]::Max($h1Scaled, $h2Scaled)
+    if ($clippedHeight % 2) { $clippedHeight++ }  # libx264/yuv420p requires even dimensions
+    if ($clippedHeight -gt $outputHeight) { $clippedHeight = $outputHeight }
+
+    if ($clippedHeight -lt $outputHeight) {
+        Write-Host ("Clip mode: output height reduced from {0} to {1} ({2}x{1})" -f $outputHeight, $clippedHeight, $outputWidth) -ForegroundColor Yellow
+        $outputHeight = $clippedHeight
+    } else {
+        Write-Host "Clip mode: sources already fill the full output height; no clipping applied." -ForegroundColor Yellow
+    }
+}
+
 $filterComplex = ""
 $inputArgs = @("-i", $S1, "-i", $S2)