I’ve had a few requests lately to send original or very large video files to clients online and when I respond that sending a portable hard drive might be more efficient, I get confused replies. To summarize the issues, and hopefully provide you with a simple and useful reference, here is a short and sweet post on the matter:
File Size vs. Transfer Time
This is the thing it comes down to: what are you asking to be delivered and how much bandwidth do you have? Video files are huge as they are, at their simplest, 24 (or more, see frame rates) images for every second of footage. Have you seen how large a single JPEG image can be? Multiply it by 24 and then the result of that by how many seconds long the piece is and you get the idea (note: I said “idea,” I did not say “the actual answer” – more on that in a second). The other factor involved is resolution (i.e.: pixel dimensions) of the video. Obviously a video at 640×480 pixels in size is going to be smaller than full HD at 1920×1080 pixels in size. But you still have the 24+ frames per second (fps) rate and you’ve only got so much bandwidth in your internet connection and time in your day…
How much speed do you actually have? You might think you have 7 Mbps or 25 Mbps connection, but that is typically advertised for the download speed only (the vast majority of internet users are consumers, not creators, after all). Upload speeds trail far behind those levels. The average internet speed for the U.S. is about 13.68 Mbps (megabits per second) download and a mere 3.65 Mbps upload (but I’m guessing you probably have something slower). And upload speed is going to be critical when you are asking somebody to “send me that video.” They aren’t going to be terribly interested in tying up their computer/connection for hours on end if they can’t charge you for the service!
The answer to video’s great size vs. time challenge is compression. Video is often times not just RAW unprocessed native signals recorded to a drive (because that is a data management nightmare and very expensive), but has some level of compression applied to keep the files manageable. There are a great many types of video compression schemes, but the most common you’ve probably run into are H.264 (for most types of online delivery) and MPEG-2 (all your DVDs use this). Your video producer is likely going to be using something much more high-quality and with less compression like maybe XDCAM, AVCHD, ProRes, DNxHD, or R3D. Let’s take a look at approximately how large one hour of 24fps 1080p HD footage might be in various formats:
- AVCHD = 12 GB
- XDCAM HD = 19 GB
- REDCODE = 30 GB
- ProRes = 60 GB
Note that I did not include H.264 or MPEG-2 in that list as a part of data compression is what bit rate you choose. This is variable depending on your needs. For example you might use 5 or 8 Mbps for YouTube or Vimeo files but a BluRay uses up to 40 Mbps. Regardless, you want to know…
But How Long Will It Take?
This online bandwidth calculator will give you an estimated download time (or upload time if you look at the corresponding rate) of your video file. You don’t need to know what compression scheme or data rate was used on the file, simply the final file’s size. For simplicity, let’s use a 1 GB video file (sometimes a streaming video file of a movie will be about this size on Netflix or iTunes because of resolution and compression) and see approximately how long it would take to upload or download. Remember that real world conditions will likely be somewhat slower due to network contention and overhead.
|Speed||1 GB||16 GB|
|768 kbps||3 hr, 6 mins||49 hr, 42 mins|
|1.5 Mbps||1 hr, 32 mins||24 hr, 43 mins|
|2.0 Mbps||1 hr, 11 mins||19 hr, 5 mins|
|8.0 Mbps||0 hr, 18 mins||4 hr, 46 mins|
|24 Mbps||0 hr, 6 mins||1 hr, 35 mins|
|50 Mbps||0 hr, 3 mins||0 hr, 44 mins|
So, the next time you ask for video files to be sent to you online, consider what it actually takes (besides disk storage). Dropbox or FTP might not be the best option if you have large or numerous files, especially as Dropbox is a mirrored folder on somebody’s computer (i.e.: yours and mine). Keep in mind that it may be quicker and easier to utilize a portable hard drive sent via FedEx!