Frame Rate Converter Calculator

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Frame Rate Converter Calculator

function calculateFrameRateConversion() { // Get input values var sourceFpsStr = document.getElementById('frc_source_fps').value; var targetFpsStr = document.getElementById('frc_target_fps').value; var hoursStr = document.getElementById('frc_hours').value; var minutesStr = document.getElementById('frc_minutes').value; var secondsStr = document.getElementById('frc_seconds').value; var resultsDiv = document.getElementById('frc_results'); // Parse and validate inputs var sourceFps = parseFloat(sourceFpsStr); var targetFps = parseFloat(targetFpsStr); var hours = parseInt(hoursStr) || 0; var minutes = parseInt(minutesStr) || 0; var seconds = parseFloat(secondsStr) || 0; // Validation checks if (isNaN(sourceFps) || sourceFps <= 0) { resultsDiv.style.display = "block"; resultsDiv.innerHTML = "Please enter a valid positive Source FPS."; return; } if (isNaN(targetFps) || targetFps 0.001) { speedChangeText = "Speed Up (" + speedChangePercent.toFixed(3) + "%)"; } else if (speedChangePercent < -0.001) { speedChangeText = "Slow Down (" + speedChangePercent.toFixed(3) + "%)"; } else { speedChangeText = "No significant change."; } // Formatting Output Duration (H:M:S.ms) var targetH = Math.floor(targetTotalSeconds / 3600); var remainingSeconds = targetTotalSeconds % 3600; var targetM = Math.floor(remainingSeconds / 60); var targetS = Math.floor(remainingSeconds % 60); var targetMS = Math.round((remainingSeconds – Math.floor(remainingSeconds)) * 1000); // Generate Results HTML var htmlOutput = "

Conversion Results

"; htmlOutput += "Total Frames in Asset: " + Math.round(totalFrames).toLocaleString() + " frames"; htmlOutput += "New Target Duration: " + targetH + "h " + targetM + "m " + targetS + "s " + targetMS + "ms"; htmlOutput += "Total Target Seconds: " + targetTotalSeconds.toFixed(4) + "s"; htmlOutput += "Speed/Pitch Shift Factor: " + speedRatio.toFixed(5) + "x (" + speedChangeText + ")"; htmlOutput += "Note: This calculator assumes a 'conform' operation, where video playback speed is altered to match the new frame rate without adding, dropping, or blending frames. This usually results in a pitch shift in audio unless corrected."; // Display results resultsDiv.style.display = "block"; resultsDiv.innerHTML = htmlOutput; }

In video production, film, and broadcast, frame rate conversion is a critical process. Different regions and delivery platforms utilize different standards for frames per second (FPS). The Frame Rate Converter Calculator above helps editors, DITs (Digital Imaging Technicians), and post-production supervisors determine how changing the playback frame rate affects the total running time of video footage.

Why Does Duration Change?

This calculator models a specific type of conversion often called "conforming" or "interpreting footage." In this scenario, the total number of frames in your video clip remains exactly the same; only the speed at which those frames are played back changes.

Think of video as a deck of cards, where each card is a frame. If you have 1,440 cards and you deal them at a rate of 24 cards per second (Cinema standard), it will take exactly 60 seconds to deal the whole deck. If you take that same 1,440-card deck and decide to deal them faster, at 30 cards per second (NTSC Video standard), you will finish dealing the deck sooner (in 48 seconds). The number of cards didn't change, only the time it took to show them all.

Common Conversion Scenarios

Here are some typical scenarios where this calculation is vital:

• Cinema to PAL (24fps to 25fps): A common European broadcast standard conversion. Cinema footage shot at 24fps is sped up by roughly 4.1% to play at 25fps. A 100-minute film will run roughly 96 minutes on PAL television. This speedup also raises audio pitch unless pitch correction is applied.
• NTSC Drop-Frame (24fps to 23.976fps): When film meant for NTSC broadcast is slowed down slightly (by 0.1%) to align with color subcarrier frequencies. This results in a very slight increase in duration.
• High Speed to Standard (e.g., 60fps to 24fps): This is how "slow motion" is created technically. You shoot many frames per second but play them back at a standard, slower rate, drastically increasing the duration.

How to Use the Calculator

To get accurate results for your workflow:

1. Enter Source FPS: The native frame rate your footage was shot in (e.g., 23.976, 24, 60). Be precise with decimals for broadcast standards.
2. Enter Target FPS: The frame rate you intend to deliver or playback at (e.g., 25, 29.97).
3. Enter Source Duration: The current length of your clip in Hours, Minutes, and Seconds.

The tool will calculate the new duration down to the millisecond and provide the "Speed/Pitch Shift Factor," indicating how much faster (>1.0) or slower (<1.0) the video and audio will play.