Video Transcript (Click to Expand)
Hi, this is Gary with MacMost Now, on today’s episode let’s use MPEG stream clip to compress video. So we get asked this question a lot, you create a video in iMovie and you end up with a file that’s just too big. Maybe it’s over the size limit for a service you’re uploading the video to, maybe you need to send it to somebody or maybe or maybe you need to put it onto a disk and it’s just too large. Well you can use a free program called MPEG stream clip to compress the video even more than what it’s compressed to when it comes out of iMovie. So here I’m running MPEG streamclip and on my desktop I have a video i’ts actually an episode of MacMost Now, directly ecported from iMovie. If I select it, and get info on it you can see that the file size is 139 “megs” and I want to make it a little bit smaller without losing too much quality. So I’m going to start by dropping the video into MPEG streamclip and it’ll apear in there, than I just simply go to file and one of the export options, now I want to export to MPEG-4 for the most compatibility and IO get this window here that has all the different options. So I want to use the H 264 compression, that’s pretty standard now. The next three settings here are all about quality, so you’re trading speed at which you can process the video for quality, so if you have all the time in the world to make a video you might as well crank it up to 100%, turn on Multipass turn on B-Frames. If you’re in a little bit of a rush, or you want to try out some different compression rates you may want to have it a little bit lower. Now some of the transitions, some of the special effects from iMovie won’t look as good with these settings so probably in your final video you want to crank it all the way up. So, the most important setting here is Limit Data Rate, this is where you can actually make your file smaller. You check that, and you get to set a kilobits per second, so lets set it at say, 2000 and you can see here on the right it gives me the approximate size of the video. Now all these other settings really don’t affect it they’re all about quality, this is saying exactly how much space per second of a video that it’s going to use. So in this case 72 “megs” is about half the size of my original video, I can make it even smaller, make it about 40 “megs” by making it 1000 kilobits per second. So, could experiment with this to find the right file size. Another setting you want to pay attention to is sound, you want to leave it at MPEG-4 AAC, you may want to play with whether you want stereo or mono, if it’s just a voice or some general audio, you may want to switch it to mono and you may want to actually decrease the rate here. These are equivalant to the settings for mp3 files actually. So, this will significantly cut a few more megabytes off by just having mono at half the kilobits per second and if it’s just voice that might be fine. Now, I can’t stress how much the quality settings affect the compression time. For instance, if you have a long video and a slower iMac you may end up taking hours to compress the video. Whereas if you set the compression level down and turn off the quality settings you can do it in just minutes. You could experimient with the rest of the settings if you like but those are the primary ones. Then you just Make MP4 and give it a file name and location, and it will begin to export the video out. Alright now that I’m done, I’ve got the original here which you can see is 139 megs and th enew version here which is advertised is just over 36 megs I can compare them by opening them both in QuickTime player so, this is the new one and I can scrub along it and see some of the quality there of the screenshots, quality of the video with me in it and then I could compare that to the original one and you can see there’s not too much of a difference, there is going to be a quality difference but I get a lot smaler file size this way than with the original. now, I do recomend a lot of experimentation. You have to figure out how much quality you want to sacrifice for the file size. One thing you may want to do is make up a very small sample movie, like maybe just about 10 seconds of the video and export that from iMovie and try a whole bunch of settings for bitrates, for quality levels inside of MPEG streamclip and find which one you want you can use MPEG streamclip’s presets to save that as a preset and you can use that over and over again while making you’re videos. So I hope you like this look at compressing video with MPEG streamclip, till next time this is Gary with MacMost Now.

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