MP4 & compression & file size, etc.

I know very little about video exporting and compression other than the most basic steps. My project is creating a long list of 4-10 minute tutorial videos for internet streaming. I have produced one video so far, and at 5 minutes, 1280x800, H264 mp4, it's 65mb. That's way too big.


After many hours of research and numerous trial exports, I'm not gaining any ground. I just don't have time to spend days/weeks learning this in depth.


I used a screen capture video program and recorded at the full screen resolution, 1280x800. The initial streaming presentation would be a smaller resolution, but should the viewer choose to go full screen, I would like it to be crisp and clear, so my goal is to maintain 1280x800, or close to it.


Lowering the quality seems to defeat the purpose as the quality is substantially degraded. My question is, what are my reasonable expectations in terms of file size for a 5 minute mp4 video at 1280x800? Is 65mb about right? I have no idea but if I have 30 videos, and 5 minutes is one of the shorter ones, that could be many many gigabytes. Is there something I am missing how to get smaller file sizes?


H264 compression was recommended, and tried out several resolutions, having to calculate different multiples of 1280x800 - it all seems very manual and tedious. I just don't know how to proceed since the first video was just so big... Any guidance is greatly appreciated! Thank you.

Macbook Pro 2.26Ghz, Mac OS X (10.5.8)

Posted on Aug 14, 2012 8:17 AM

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3 replies

Aug 14, 2012 12:48 PM in response to Christopher Davis2

I know very little about video exporting and compression other than the most basic steps. My project is creating a long list of 4-10 minute tutorial videos for internet streaming. I have produced one video so far, and at 5 minutes, 1280x800, H264 mp4, it's 65mb. That's way too big.

Actually, 65 MBs is quite a reasonable file size for a 5-minute, 1280x800, H.264/AAC MP4 file. (File Size = Total Duration X Total Data Rate so your data rate is only on the order of 1.7 Mbps which was originally the limit for 640x480 5th generation iPod files.) In order to make the files smaller you will have to either settle for reduced video quality and/or a smaller display size. (You could, for instance, create a 1024x800 anamorphic encode that displays as a 1280x800 file, but this would only reduce the file size by a small amount whereas a 640x400 non-anamorphic file could cut the file size significantly while retaining similar quality in the smaller display. In short, you need to re-evaluate your streaming/fast start requirements. (I.e., I typically use 2 to 4 times your data rate for what I consider "good quality" 720p24 file encodes for viewing on HD capable devices.)



After many hours of research and numerous trial exports, I'm not gaining any ground. I just don't have time to spend days/weeks learning this in depth.

It is unlikely you will be able to further reduce your file size without a loss in video quality and/or a reduction in the file's display dimensions.



I used a screen capture video program and recorded at the full screen resolution, 1280x800. The initial streaming presentation would be a smaller resolution, but should the viewer choose to go full screen, I would like it to be crisp and clear, so my goal is to maintain 1280x800, or close to it.

The only way to reduce file size is to either "throw away" data or use a more efficient, higher compression codec. H.264 is about the most scalable, highly efficient, highest compression capable codec you can use which is why it is used for everything from FaceTime to BD/AVCHD encodings.



Lowering the quality seems to defeat the purpose as the quality is substantially degraded. My question is, what are my reasonable expectations in terms of file size for a 5 minute mp4 video at 1280x800? Is 65mb about right? I have no idea but if I have 30 videos, and 5 minutes is one of the shorter ones, that could be many many gigabytes. Is there something I am missing how to get smaller file sizes?

"Reasonable epectations" are realative—and may be quite different for each person. Basically, the expectation is reasonable if the file delivers the quality you want at the display dimensions you want in a file size with which you can live. If not, then you have to re-evaluate your "expectations." Further, encoding is driven by the content itself with every file being different and should be treated as such depending on the graphic complexity of the content, the number/type of vector motions involved, ratio of light:dark scenes, display dimensions, etc. There is no "one shoe fits all" here and what is "reasonable" for one file may not be "reasonable" for another. What you are actually missing here is an overall goal strategy.



H264 compression was recommended, and tried out several resolutions, having to calculate different multiples of 1280x800 - it all seems very manual and tedious. I just don't know how to proceed since the first video was just so big... Any guidance is greatly appreciated!

You say you are creating tutorial files for internet streaming. If this is your goal, how do you plan to deliver these files in terms of internet connection speeds? The target speed for internet delivery will determine the data rate limits within which you must work. Once you determine the playback data rate limits for target users, you will know the data rate limits at which to encode your file for playback. In turn, this data rate will determine the combination of display dimensions and level of video quality you will have to accept. At this point the size of individual files is of lessor importance because once the file begins to stream or play in the fast "start mode," the file can continue to play as the data continues to stream or download to the end user's local platform/media player. In fact, at this point you can actually decide if you want to create multiple file versions for users having different target internet connection speeds or just a single file. Frankly, until you are able to answer such questions, there is very little advice that anyone can give you.


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Aug 15, 2012 11:51 AM in response to Jon Walker

Wow thank you. This is exactly the kind of detailed response I needed.


Referring to your last paragraph about data rates and delivery speed for target users, my understanding is that well, everyone is on Broadband these days. Isn't that one speed, within a certain range, whether it's DSL or cable modem, etc? I don't know what "data rate limits" are for individual broadband suppliers/users, but I would respond "broadband." I'm probably not fully understanding this. Is there some chart that says matches data rate limits for a viewer with data rate for encoding/playback?


After this post I did manage to export the aforementioned file (which came to 65mb at the defaults for H.264 originally) at: AAC, Stereo (L, R), 44.100 kHz, H.264, 768x480, Millions, 15 fps; Data rate 332.86 kbits/s.


It came to 13 mb, decent quality, maybe a little fuzzy at full screen. So that might work


I will experiment with creating two versions however depending on the viewers data rate. I guess my underlying concern is creating 30, 100+ mb files, I'm not sure my hosting storage can accommodate all that.


Thanks very much, I will review your response in detail and continue sorting this out.

Aug 15, 2012 2:27 PM in response to Christopher Davis2

Referring to your last paragraph about data rates and delivery speed for target users, my understanding is that well, everyone is on Broadband these days. Isn't that one speed, within a certain range, whether it's DSL or cable modem, etc?

Not at all. Basically, you get what you pay for. In my area, Verizon FIOS offers speeds from 15/5 Mbps to 150/50 Mbps. (I'm on a 35/35 Mbps small business plan for my home so I could get a static IP address for my own personal web server following the demise of MobileMe.) For the most part, the data rates vary by service provider and level of service purchased by the user. Therefore, it is a common practice to create "reference files" which vary as to display size and distrubution data rates so the recipient can either select the file best suited for his individual viewing needs or allow his or her software to automatically select the file best suited to his or her system and internet connection speed.



After this post I did manage to export the aforementioned file (which came to 65mb at the defaults for H.264 originally) at: AAC, Stereo (L, R), 44.100 kHz, H.264, 768x480, Millions, 15 fps; Data rate 332.86 kbits/s.

Just an FYI... I noticed you mentioned a 15 fps frame rate. Many people seem to think lower frame rates equate to lower data rates. They don't. Frame rates and key frame rates determine how the data is distributed between frames over the unit time. If your tutorials are mainly static (i.e., little vector motion limited fades or other effects), then lowering the frame rate and extending the time between key frames may help reduce file size—but don't rely on this to work well with all types of content.



I will experiment with creating two versions however depending on the viewers data rate. I guess my underlying concern is creating 30, 100+ mb files, I'm not sure my hosting storage can accommodate all that.

If you have an HD movie clip handy, open it in the QT X Player and export it for web using all available options. When done, follow the instructions to online test what you've created to see how this would work on your web site.


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MP4 & compression & file size, etc.

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