What is Bit Rate?

Every time you record, export, or watch a video, bit rate has a lot to do with the quality. Learn what bit rate is and how it affects file size, image quality, accessibility, and delivery cost. Plus find out the difference between CBR and VBR.

Wolfram|Alpha Bit Rate Calculator

Containers, Codecs, and Formats

Comments

Contradiction question

Zvi's picture

Hey Mike. You said towards the end that since Youtube compresses video it's best to upload a higher bitrate so even after Youtube's compression you will be left with a decent quality. But toward the beginning of the video you explained that the higher the resolution is, the more compression it will need to obtain a lower bitrate. So wouldn't it be better to try and match youtube's final bitrate output instead of maximizing it before upload?

Youtube Compression

cinemapete's picture

From what I've been able to find, Youtube doesn't set a bit-rate limit for H.264 uploads, and Youtube will use various codecs when it processes an uploaded video (using different codecs and bit rates) so that it can be played back on various devices. However, no limit on H.264 uploads still does not answer the basic question of whether the final video, say for a desktop stream, will be compressed down to a constant and fixed bit-rate - which is not desirable since it would mean that no matter how high the bit-rate for the uploaded video is it will always be compressed down to a fixed bit-rate - as opposed to using a percentage compression rate. For example, if your original bit-rate is 12 mbits/second and Youtube uses a fixed compression of 6 mbits/second, then the uploaded video would be compressed by a factor of 2 with 6 mbits/sec loss. Whereas, if a fixed percentage-based compression is used and that percentage is say, 30 percent, then that same 12 mbits/sec video would then be compressed down to 8.4 mbits/sec (with a loss of 3.6 mbits/sec). In the case of a percentage-based compression it would make sense to use the highest bit-rate (i.e. the original). What is not clear from Youtube that I could find was whether or not they use a fixed bit-rate for their compression or not. Perhaps someone else can shed some light on this. In any case, Youtube does have a recommended bit rate for uploaded video that can be found here: https://support.google.com/youtube/answer/1722171?hl=en

Background Music

cinemapete's picture

I'm not adverse to background music for videos, in fact I use background music for certain videos where it's appropriate. However, there's absolutely nothing wrong with NOT using background music for an instructional video such as What is bitrate. What is especially annoying with many videos is that the music is a distraction for many viewers because the brain automatically focuses on music (especially if one is musically inclined) and for many it's distracting when there is a speaker. The distraction is particularly acute when the music contains a persistent and endless beat (as does the What is bitrate? video). Now can you imagine listening to a news report with music constantly in the background that has a pervasive beat that competes for your attention, or better, a college lecture with a constant background sound track? Why? Silence can be golden. On the plus side I will say that whom ever created the video had the sense to drop the music down when ever the presenter speaks. Without being overly critical, which I think some will feel is the case with my comments here, I would strongly suggest that VIdeomaker not add such unnecessary and distracting background music in what is otherwise a very interesting and useful video. Thanks Videomaker.