How to export video in same settings as source video?

I have a 50 MB file, imported it in Hitfilm  express and all I did was removed existing audio and added new audio. Didn't touch the video. Exported it by creating a new preset with resolution set as that of source. The original video resolution is 360p, still changed the video quality from higher to lower and the file size was 360 MB!! Why so much increase at reduced settings?

I would also like to know how to edit and export the video in exactly the same settings as source file.

Comments

  • Triem23Triem23 Moderator

    You will have to download and install a free program called MediaInfo.

    You will have to use MediaInfo to discover the bitrate settings of your original video.

    You'll have to do some very basic math.

    We'll try a hypothetical example. I won't be using MediaInfo, I'll be using some extra math.

    You have a 50MB 360p video. File size is measured in megaBYTES  (MB) while encoding bandwidth is measured in megaBITS (mb - YES captial vs lower case letters have different meanings here). A BYTE is 8 BITS, so I'm going to multiply 50MB by 8 to get 400mb

    OK, so, we have a 400 megabit file. Let's make it exactly 2 minutes long. That's 120 seconds. The frames per second doesn't matter, because files are encoded in megabits-per-second.

    This gives me a value of 3.3333 megabits per second. If I had you original file I could just drag it into Mediainfo and find the encoded bit-rate instead of everything I just did.

    Anyways, we've figured out our "example file" is 3.333mbps. So, we trim and we select Export.

    Hey, the default export rate is 20mbps! That's a bit over six times as large as your input bitrate, and this would output a 300+ megabyte file! These random numbers I pulled are pretty close to what actually happened for you!

    Anyway, point here is, how low did you set your mbps on output. If I want the same file size I need, roughly, the same bitrate. For this example we want to set the output bitrate at about 3.33 mbps.

    That said, you might not WANT to shrink your file down to the same size. mp4/h.264 recording is LOSSY. This means it throws data away. That data, once gone, can never be recovered.

    The uncompressed data rate for your original video can be estimated as follows (pixel width * pixel height) * 24 * frames per second = number of bits per second. (640 * 360) * 24 * 29.97=165,722,112. We take bits-per-second and multiply that by 1024 to get k/bits per second, then by 1024 again to get m/bits per second.

    I'll spare you the math. The final value is a bit over 158mbps. The "Example" video above was compressed as 3.333 mbps. This means the video was compressed at a ratio of almost 50 to 1. This is pretty big....

    When you load a video into an NLE it must be uncompressed. NLE's are working with full-bitrate files. If you saved our your edit at 3.3333mbps.... You'd have loaded video compressed in a LOSSY format at a 50:1 ratio, edited that then RECOMPRESSED it, again and 50:1. There's a good possibility your final rendered output will look terrible.

    You might need to try a couple of tests to find that sweet spot where the render looks ok and the file size is pretty small.

    Anyways, that answers your question and gives you a lot of extra information, including why you might have asked the wrong question! Hope it all makes sense!

  • Thanks a lot for your detailed answer!

    Exported file after modifying the bitrate is now 67 MB!

  • Triem23Triem23 Moderator

    Good! How did the output hold up? Still look ok? For a small frame like yours there's going to be less "damage" from compression than, say a 4k file  so it's probably fine. 

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