Trying to render a .mov and keep it under 750 mb

I'm trying to take a 400 MB .mov file from a Kodak Zi8 and import it into Kdenlive in order to add a couple of jpgs as well as a 15 mb audio file into a separate audio track. I first tried to render it to just a plain .mp4 ( but not the H.264 Mp4 format ) It took two hours to render it and the total video is only 20 minutes. Does that sound correct? Since the file from the camera is a .mov should I render it as a H.264 and go thru the process of creating a new profile so the finished product comes out as a .mov too? I'm trying to upload this to TwidVid when I'm finished and the problem with the way that I already attempted to do this as an Mp4 created a finished file size of 1.4 GB. Remember it's only a 20 minute video. The finished video does look great but I would prefer a little less video quality, the best Audio quality and somehow to keep the final file size under 750 MB. Any recommendations on what I could do or suggestions? Thanks, Rich H


Rendering time depends on the source material compression (r.g. AVCHD has slow seeking) and the number of effects and transitions used. Even more heavy weighs the hardware you use for rendering. In Kdenlive you can set the number of threads for rendering (in the render mask), which should be max. the number of threads your CPU can handle. A double core can handle two threads, a double core with hyperthreading (Intels HT technology) can handle 4 threads. Quad cores can handle 4 or 8 threads. All in all the render time of your movie is nothing special.

The codec you choose for rendering depends on where you want to watch your movie. h.264, resulting in an mp4, is a good choice to be uploaded to video sharing sites or to be watched on HD television or computer screen. But it has to be transcoded if you want to burn it on a DVD (which needs mpg2). From my point of view h.264 is a good choice for you.

The size of your renderd movie depends on the bitrate you choose. To get close to 750MB in the end, we must calculate a few things.

Calculating the bitsize of your rendered movie
(1 MB = 1024*1024 bytes = 1.048.576 bytes | 1 byte = 8 bit)
Given the total target size of 750MB: 750MB = 750*1048576bytes = 786.432.000 bytes, which is 786.432.000 * 8 = 6.291.456.000bits)

Calculating the length in seconds
20 minutes of video = 20*60s = 1200s

Calculating the bitrate
6.291.456.000bits / 1200s = 5.242.880bits/s

If you choose about 5M bit/s (or 5000k bit/s) you should end up pretty close to 750MB movie size. But if your source movie comes in ~2700kbit/s (400MB for 20 minutes) I would not expect to see much difference between 3000kbit/s and 5000kbit/s. You can try both bitrates with a small portion of your movie (set in and out point in timeline using i and o keys, choose render selection in render dialog) and decide. :)

Cheers, Achim

Good info Achim! This is starting to make more sense. I'm going to run a couple of those tests you suggested. Thanks again, Rich H