A version that captures bounding box regions too

macos/quicktime-capture-script.md

@@ -61,3 +61,137 @@ It took multiple rounds of prompting to figure this out - the most relevant tran
 The frames it produced are a good combination of quality and filesize. Here's one, which is an 80KB JPEG:
 
 ![Frame from a video, showing a slide image displayed in a Firefox window](https://static.simonwillison.net/static/2024/frame_000023.jpg)
+
+## A version that captures bounding box regions too
+
+I gave a talk at a conference where the resulting video featured both my on-stage presence and a superimposed output from my screen.
+
+I wanted to grab captures of both - a full screen capture, but also a capture that only showed what was on my screen at the time.
+
+I got Claude to update my script for that ([first session](https://gist.github.com/simonw/799babf92e1eaf36a5336b4889f72492), [second session](https://gist.github.com/simonw/03b0cff88f9b9cbb7af879a07512bf6f)) resulting in this script:
+
+```zsh
+#!/bin/zsh
+
+# Initialize array for storing bounding boxes
+typeset -a bounding_boxes
+
+# Parse command line arguments
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        --box)
+            if [[ $2 =~ ^[0-9]+,[0-9]+,[0-9]+,[0-9]+$ ]]; then
+                # Validate coordinates are within 0-100 range
+                local coords=(${(s:,:)2})
+                local valid=true
+                for coord in $coords; do
+                    if (( coord < 0 || coord > 100 )); then
+                        valid=false
+                        break
+                    fi
+                done
+                if $valid; then
+                    bounding_boxes+=($2)
+                else
+                    echo "Error: Bounding box coordinates must be between 0 and 100"
+                    exit 1
+                fi
+            else
+                echo "Error: Invalid bounding box format. Use: --box 'x1,y1,x2,y2' where coordinates are percentages (0-100)"
+                exit 1
+            fi
+            shift 2
+            ;;
+        *)
+            video_filename=$1
+            shift
+            ;;
+    esac
+done
+
+# Check if the video filename is provided
+if [[ -z $video_filename ]]; then
+    echo "Please provide the video filename as an argument."
+    exit 1
+fi
+
+# Function to convert time in seconds to HH:MM:SS format
+function seconds_to_hms {
+    local total_seconds=$1
+    local hours=$((total_seconds / 3600))
+    local minutes=$(((total_seconds % 3600) / 60))
+    local seconds=$((total_seconds % 60))
+    printf "%02d:%02d:%02d\n" $hours $minutes $seconds
+}
+
+# Function to capture frame with optional bounding box
+function capture_frame {
+    local current_time=$1
+    local bbox=$2
+    local formatted_time=$(seconds_to_hms $current_time)
+
+    # Base filename without bbox suffix
+    local base_filename="frame_${formatted_time//:/}"
+
+    if [[ -z $bbox ]]; then
+        # Capture full frame
+        local filename="${base_filename}.jpg"
+        ffmpeg -y -ss $formatted_time -i "$video_filename" -frames:v 1 -f image2 "$filename"
+        echo "Saved full frame to $filename"
+    else
+        # Capture cropped frame using the bounding box
+        local coords=(${(s:,:)bbox})
+        local x1=$coords[1]
+        local y1=$coords[2]
+        local x2=$coords[3]
+        local y2=$coords[4]
+
+        # Calculate width and height as percentages
+        local width=$((x2 - x1))
+        local height=$((y2 - y1))
+
+        local filename="${base_filename}_bbox${x1}_${y1}_${x2}_${y2}.jpg"
+        ffmpeg -y -ss $formatted_time -i "$video_filename" \
+            -vf "crop=iw*${width}/100:ih*${height}/100:iw*${x1}/100:ih*${y1}/100" \
+            -frames:v 1 -f image2 "$filename"
+        echo "Saved cropped frame to $filename"
+    fi
+}
+
+# Main loop
+while true; do
+    echo "Press any key to capture the current video frame..."
+    read -sk 1 key
+
+    # Use osascript to get the current time from QuickTime Player
+    current_time=$(osascript -e 'tell application "QuickTime Player" to tell document 1 to get current time')
+
+    # Capture the full frame first
+    capture_frame $current_time
+
+    # Then capture each bounding box if any were specified
+    for bbox in $bounding_boxes; do
+        capture_frame $current_time $bbox
+    done
+done
+```
+
+This can be run like so:
+
+```bash
+capture-bbox.sh ../output.mp4  --box '31,17,100,87' --box '0,0,50,50'
+```
+You can use the `--box` option 0 or more times. The output for each frame will then look like this:
+```
+frame_003844.jpg
+frame_003844_bbox0_0_50_50.jpg
+frame_003844_bbox31_17_100_87.jpg
+```
+That's the original frame and an image for each of the specified bounding box regions.
+
+The `--bbox` format uses percentages along the width and height of the image.
+
+I also [got Claude to build](https://gist.github.com/simonw/799babf92e1eaf36a5336b4889f72492#create-bounding-box-drawing-tool) a visual tool for selecting these. Drop a full screen frame from an image into this [Bounding Box Drawing Tool](https://tools.simonwillison.net/bbox-cropper) and drag the box to find out the correct `--box` setting:
+
+![Screenshot showing a box dragged around a section of an image with a --box output below it](https://github.com/user-attachments/assets/71064215-d3b1-4b5a-b45e-2358f96a9459)
+