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export as 1280×720 or 1920×1080 has the same file size
Hi,
I couldn’t really find much on this topic by googling so i thought i’d ask the pro’s here.
Let’s say i have a 2-minute project with a combination of 1920×1080 5d mark 3 footage and after effects titles etc. If i export the project to an MP4 in 1920×1080 with a target/maximum bitrate of 10mb then i get a file size of 200mb for example.
If i render the exact same project to MP4 in 1280×720 with the same target/maximum bitrate then why isn’t the file size smaller? I notice it to be basically the same, no matter on the project or content.
Appreciate the help,
Thanks,
Sean. -
3 Replies
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[Sean Jahnig] “If i render the exact same project to MP4 in 1280×720 with the same target/maximum bitrate then why isn’t the file size smaller?”
Because the bitrate is the same. You could export a 4K sequence with the same settings and the size will be the same. In compressed formats you should give larger resolutions more bitrate so they’ll look better but resolution itself will not matter in the size. If you use uncompressed formats then resolution would change the final size because every pixel at every frame would be drawn at the selected bit depth.
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Great, thanks for explaining that. Now that i think of it, it makes sense.
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If you give it a bitrate of lets say 4 mbit it will only use that. It will cram 4 mbit/s to the file as best as it can. It may not be enough for the resolution or frame rate but it will deal with the attribute you’ve set.
VBR is a different thing because you can set min/max bitrates and if the codec can encode something more efficiently then it can change its parameters on the fly depending on what it “sees”.
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