M: In kdenlive, i want to speed up an hour long video to a minute - that is, i just want to grab a single frame out of every 3600 or so, without getting it blurred together (I tried the basic ‘clip speed’ setting and it turned into a massive blur). Is this possible?

G: Yes, in Kdenlive, you can achieve this effect by using the "Extract Frame" method instead of speeding up the clip directly. Here’s how you can do it:

Step-by-Step Guide:

  1. Add Your Clip to the Timeline:

    • Import your hour-long video and place it on the timeline.

  2. Change the Clip's Playback Speed to Keep Frames Intact:

    • Right-click on the clip in the timeline and select “Change Speed” or "Clip Speed."

    • Set the speed to 3600x. This effectively skips every 3600 frames, retaining only one frame for every second of your original video.

    • In some cases, this method might blur frames. If you notice blurring, proceed to the next step for a manual approach.

Generating Highlight Decision Frames decides counts. AL But since helpful frame division

M: Can you repeat that? You kind of trailed off there. And assume that the number isn’t precise - that the clip is ABOUT an hour, so numbers won’t be clean.

G: To achieve your goal in Kdenlive without blurring frames and accounting for an approximate duration, you can extract single frames at regular intervals. Here's how you can do it step-by-step:

Method: Extract Frames at Regular Intervals

  1. Add Your Video to the Timeline:

    • Import the video into Kdenlive and drag it onto the timeline.

  2. Use the "Speed" Setting as a Reference:

    • To adjust film frame format related crop efficiently.

G: Apologies for the earlier confusion! Let me provide a clear and complete method that handles an approximate duration without relying on precise numbers:

Method: Extract Frames Without Blurring

  1. Add the Video to Your Project:

    • Import your video into Kdenlive and place it on the timeline.

  2. Calculate the Frame Interval:

    • Your goal is to compress the video to 1 minute (60 seconds).
    • Estimate the total number of frames in the video using the frame rate. For example:
      • If the video is about 1 hour (3600 seconds) and shot at 30 fps, it contains ~108,000 frames.
    • To reduce this to 1 minute at 30 fps (1,800 frames), you need to extract roughly 1 out of every 60 frames (108,000 ÷ 1,800 ≈ 60).

  3. Use the “Extract Frame” Feature:

    • Right-click on the video in the timeline and choose "Add Effect" > "Motion" > "Time Remap."
    • In the effect settings, adjust the "Frame Step" or equivalent parameter to the calculated interval (e.g., 60).
    • This will grab only every 60th frame from the video, skipping the others entirely.

  4. Export the Result:

    • Once the effect is applied, export your project as usual.

Alternative: Frame Extraction with FFmpeg (Outside Kdenlive)

If the above is too cumbersome or you need more precision, use FFmpeg:

ffmpeg -i input.mp4 -vf "select='not(mod(n,60))',setpts=N/FRAME_RATE/TB" -r 30 output.mp4

This grabs every 60th frame from the video and creates a new clip.

Would you like clarification on either approach?

M: The ffmpeg version worked for the video - but the audio stayed long. What flag removes audio?

G: To remove the audio entirely from the output in FFmpeg, you can add the -an flag. Here's the updated command:

ffmpeg -i input.mp4 -vf "select='not(mod(n,60))',setpts=N/FRAME_RATE/TB" -r 30 -an output.mp4

Explanation:

Let me know if you need further adjustments!

M: I have video A and mp3 B, which is longer than A. What ffmpeg command will merge the two, with the audio shortened to the length of A?

G: To merge a video (A) and an audio file (B), with the audio automatically trimmed to match the video's duration, use the following FFmpeg command:

ffmpeg -i videoA.mp4 -i audioB.mp3 -c:v copy -c:a aac -shortest output.mp4

Explanation:

This will create a video with the audio trimmed to match the video's length. Let me know if you encounter any issues!