Intro to Bit Rate for New Filmmakers and Vloggers
Bit Rate can be a confusing topic when it comes to videography. You start throwing around terms like resolution, frame rate, HD, and it becomes a jumble of perplexity. In reality, bit rate is none of these things.
Bit Rate is the amount of data encoded per second when you shoot video. The higher the bit rate, the higher the quality of your video. There is, however, a trade off. If you shoot at a high bit rate, you must deal with large file sizes. As your bit rate goes up, so do the file sizes of the videos you are recording. More data per second, more space taken up.
Bit Rate is Not the Same Thing as Resolution
Many people confuse bit rate and resolution. They are independent of one another. Resolution is the pixel size of your video. It does not necessarily determine the quality of your video. Sure, when you have a higher resolution like 4K, you generally have a better looking video. But that is because cameras will generally record at a higher bit rate for these larger resolution files. If we kept the bit rate constant and shot two videos – one at 1080p and one at 4K – you would notice that the 1080p video might actually look better. The 4K video must spread all of this data over a larger pixel area, thus compromising the look.
Let’s look at an example. Take the same standard 1920 x 1080 HD shot. If we encode this video at two different bit rates, you will notice a difference in the quality. Both shots are considered HD because they have a resolution of 1920 x 1080, however they are not equal. The video on the left has a much more pixelated, low quality image. The video on the right is much better quality, but it is over 5 times as large in file size.
Not all cameras shoot at the same bit rate. This is why an iPhone looks different than a GoPro and a DSLR. Each camera has its own options for bit rates at which it can record. Even though all of these cameras can record 1920 x 1080 HD footage, they do not all look the same. There are additional factors like sensor size that affect why these cameras have different looks, but bit rate is a large part of the equation.
Bit Rate on YouTube and other Platforms
Bit rate is measured in megabits per second (Mbps). When you watch a video on YouTube at 1080p HD, the average bit rate of the video you are watching is 8-12Mbps. When you upload your videos to YouTube, the site automatically encodes your video to the ideal settings for each of the resolutions they offer. So if you upload a high bit rate video to YouTube and select to watch it back at 360p, YouTube will have already encoded a file for that size that has a bit rate in the .5-1Mbps range. This allows you to watch most videos no matter the strength of your internet. It is recommended to upload the highest bit rate version of your video – YouTube can’t increase the bit rate of your video.
Because of the development of technology over time, we now consume our content at much higher bit rates than in the past. DVDs played videos at a bit rate of 4-8Mbps. BluRays are capable of holding much larger files, so they play videos at 24-40Mbps. Hulu and Netflix are now pushing these limits as well, offering much higher bit rates for fast internet connections.
Variable vs Constant Bit Rate
When you are encoding/exporting a video file, there is an important difference to understand: Variable Bit Rate vs Constant Bit Rate. If you choose to export with a Constant Bit Rate (CBR), your entire video will be your target bit rate, no matter what. If you choose to export at 10Mbps, every second of your video will be just that: 10Mbps.
If you choose to export with a Variable Bit Rate (VBR), your video bit rate will adjust depending on what is happening within your video. If you have a portion that has no movement or is just a black screen, the video will encode with a lower bit rate during that portion. When you export with VBR, you choose a target bit rate and a max bit rate. VBR is generally a more efficient encoding method that results in smaller file sizes.
Recording at a lower bit rate can sometimes be just what you need if you want ease of file storage and file transferring. Remember that when you’re uploading files to YouTube or Dropbox, you don’t always want massive files. Sometimes you might want to compress the file to a lower bit rate to allow for faster file transfer.
Conclusion
The higher the bit rate, the higher the quality of the video. The higher the bit rate, the larger the file size. Remember this! This is the reason why powerful, high bit rate cameras need special memory cards to record (SSDs and CFast cards, for example). These cameras record at such high bit rates that a standard SD card can’t record the data fast enough or will fill up too quickly.
I hope this helps shed some light on bit rate and helps you more easily choose the right camera for the right project. Examples of cameras that shoot at higher bit rates (at the time of this writing) include the Panasonic AG-CX350 4K Camcorder, the Blackmagic Pocket Cinema 4K, the Sony a6400, the Panasonic GH5, the Canon C200, and the Fuji X-H1. As you can see, higher bit rates are available in a wide variety of form factors and price points. You don’t necessarily have to spend a lot to achieve high bit rate footage, but you will need a lot of storage no matter what system you go with.
Kellan Reck
Kellan Reck is a video editor and cinematographer for the Boston Red Sox, producing and building content for the team's social media platforms and Fenway Park's video boards. This work with the team has awarded Kellan four New England Emmy Awards. Additionally, Kellan runs a YouTube channel where he shares tutorials, tricks, and more that help other filmmakers develop their skills. Enjoy a new video every Wednesday at 10 AM!
8 Comments
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Dan Delaney
They are indeed. Apple has already switched their iPhone Camera app to save all videos encoded in HEVC/h.265, which makes them half the size they used to be. (Although, if you share them outside of the Camera app or the Mac Photos app, it will automatically convert them to AVC/h.264.)
One other thing I forgot to mention: The difference in quality between the DVD and Blu-Ray clips you displayed was a consequence of the different resolutions (480p vs 1080p) between the two, not of the different bitrates. Blu-Ray uses higher bitrates because of the higher resolution. 4-8 Mbps is plenty for the low resolutions of DVDs.
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Dan Delaney
Excellent! Yeah, WordPress themes can be extremely convoluted.
Another thing I noticed with the alterations you’ve made on top of this theme’s styles is that the change of font to Ubuntu from the original theme font (Raleway) has left the body copy all bold. In /blog/wp-content/themes/i/style.css on line 58, the font-weight for the entire of the page is set to 500, which is effectively “Semi-Bold” in the Ubuntu font you’re using. With typical fonts that only have two weights, 400 is considered “normal” and 700 is considered “bold”. A weight of 500 made sense for the Raleway font that was specified in the original theme style because it happens to be one of the few fonts that has NINE weights! That font, however, is being superseded with the Ubuntu font in the fourth tag in the of the page itself. The Ubuntu font (a very nice choice, BTW) happens to have four weights: Light (300), Regular (400), Medium (500) (aka, Semi-Bold), and Bold (700). So a font-weight of 500 for this font is essentially “Semi-Bold”, which is “flattening” the text typographically so that anything bolded doesn’t stand out. Typically, the “Regular” weight is used for body copy, but in my experience if a font has a “Light” weight, that’s usually ideal for body copy; it allows you to get a beautiful contrast between Light and Bold when you want certain things to stand out.
Try setting font-weight to 300 on line 58 of style.css and see how that looks. It gives the entire page a much cleaner look that’s easier on the eyes. The only thing I notice with that weight on your page is that the line just under the title is a bit thin, but that’s just because it’s extremely small (11px) compared to the body copy (16px). Try also setting the font-size to 14px in the “.post-meta” class in the seventh tag of the page. That ends up looking really nice. 🙂
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Kellan
Dan, I appreciate the comment. Very good to know. Glad you put it to the test to clarify. These newer codecs are truly impressive too.
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Alexandria Huff
Huzzah! I found it. There are, like, three different areas in this theme where date can be controlled and there was a deeply buried one that was turned off. 😀
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Dan Delaney
:-D. No telling why it’s not displaying. WordPress can be tricky sometimes, especially with the more complicated themes. Find the template files for your theme and see if you can find the place where it’s outputting the title (with the get_the_title() PHP function) and author (with the get_the_author() function). The date should be output with the get_the_date() function.
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Alexandria Huff
I’ll let Kellan speak to the content of your comment but I am just here to chime in on how weird it is that our dates are not showing! All of our settings are set to show dates and yet – you’re right – they are simply not displaying. I am investigating. In the meantime, the date for this piece is Apr 4, 2019.
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Dan Delaney
Thanks for the article, Kellan. Nicely done.
One major correction, though: You wrote, “When you watch a video on YouTube at 1080p HD, the average bit rate of the video you are watching is 8-12Mbps.” That’s incorrect. YouTube recommends that 1080p videos be uploaded at 8 Mbps or higher so that the backend processor has a lot of detail to work with when re-encoding to the various sizes and formats YouTube actually serves. But after the video is uploaded, it is re-encoded and served at much lower bitrates. YouTube will typically send a 1080p MP4 video encoded with the AVC/h.264 codec at around 1.5 to 2 Mbps.
It’s actually more complicated than that, however, because the newer codecs (like HEVC/h.265 and VP9) can achieve the same quality at roughly half the bitrate as the older codecs. Whenever possible (as it is with all major browsers now), YouTube will send videos in the WEBM format encoded with the VP9 codec. So when you view a 1080p video from YouTube these days, you’re most likely receiving a WEBM file encoded with the VP9 codec at less than 1 Mbps.
So, as a test case, I just uploaded a 23 minute, 1440p (i.e., “2K” ) video encoded with the HEVC/h.265 codec with a bitrate of 9.9 Mbps. Once YouTube had completely finished processing all the various sizes it makes available, I downloaded the resulting 1080p videos it had produced. The AVC/h.264 version had a bitrate of 1.86 Mbps (1857 Kbps) and the VP9 version had a bitrate of 0.75 Mbps (752 Kbps)! (The 720p AVC/h.264 version had a bitrate of 922 kbps.)
(Sorry if it’s been a long time since you posted this. Because BorrowLenses doesn’t display the dates of blog posts, I don’t know if you posted this a few days ago or a few years ago. )
Cheers
—Dan
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Tali Shlafer
Very useful article. Thank you for breaking this down in a simple, unintimidating way, and for offering a plethora of examples.