Old 10-13-2021, 11:03 AM   #1
AndoLaw
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Default .MP4 vs .mov file size

Hi All:
I just learned (what I thought was) a neat trick for rendering as MP4: specify ".mp4" in the Output>File Name when rendering. I just did that and, sure enough, the file rendered as MP4, rather than the default .mov I've been getting.

However, I thought the MP4 files would come out a lot smaller, but comparing the new one with the .mov version of the same project I get exactly the same file size. Anybody know why?
Thanks much,
Andrew
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Old 10-13-2021, 11:45 AM   #2
AndoLaw
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Just did a little experiment. Instead of re-rendering the file with .mp4 in the file name, I converted the file from .mov to .mp4/mv4 using handbrake. File size went from around 1 GB to 1/10th of that.

So...what? The "MP4" file referenced in my original post isn't in fact MP4?
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Old 10-13-2021, 12:26 PM   #3
bazz02
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Default Handbreak

Hi.Noticed that as well.Setting Handbreak to MP4 renders a .m4v file.

I have to say quality is exceptional given the reduction in file size.
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Old 10-13-2021, 12:58 PM   #4
AndoLaw
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I noticed that handbrake defaults to Mv4 when you opt for MP4, too. And yes, I can't tell the difference between the files. Impressive.
What I don't understand is why I didn't get the same reduction when I rendered the file as MP4 using the method I described in my first post. Either:
> I wasn't really rendering it as MP4, OR
> There's some other difference between the 2 Mp4/M4v files I've created.
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Old 10-13-2021, 04:13 PM   #5
ashcat_lt
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Changing a file extension doesn't really change anything about the file itself. More importantly, .mp4 and .mov files are actually just containers and don't necessarily imply anything about the compression algorithm for the video part of the file itself. You need to change the quality settings in the Render window to change the amount of compression to change the file size.
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Old 10-13-2021, 04:16 PM   #6
babag
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mov and mp4 are what's called 'container' formats. containers can contain a variety of things, from subtitle materials to audio and video files. in the case of video, the codec of the file in the container will go a long way to determining the end file size.

sounds like what you originally did was to switch containers from mov to mp4 without changing the codec of the video contained therein, hence, same file size. when you went to handbrake, you changed the codec from whatever it had been to the highly compressed m4v codec, hence, much smaller file size.

babag
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Old 10-13-2021, 05:59 PM   #7
AndoLaw
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I get it. Thanks for the replies!
~Andrew
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Old 10-14-2021, 04:43 PM   #8
TrollE
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I was just coming here to ask these same questions. I asked on the Reaper subreddit a yesterday about how I can convert my video files to a smaller size and folks there instructed me to download and install "ffmpeg.dll" which I did to no avail.
Now, how do I change the codec and file type in reaper? I can't seem to get past huge files more than 5x the original file size of the original video I was editing.
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Old 10-15-2021, 08:10 AM   #9
papagirafe
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A compressed source video needs to *expanded* to full frame/framerate in real time to allow editing in Reaper (or any video editing app).
On the output side video compression is mainly achieved by calculating pixel differences between "key frames" and by using mathematical and statistical wizardry. For maximum compression you need a near complete view of the final video to find the best keyframes and to collect statistical information. Since the final video is being generated in Reaper you clearly do not have enough information to fully compress, hence the suggestions to use Handbrake (or similar) as a second step to further compress.

Last edited by papagirafe; 10-15-2021 at 08:59 AM. Reason: typo
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