Why is 76-100% quality offered if it's not recommended?

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I'm just asking this out of curiosity... When rendering a video, if you go above 75% quality, you get the message, "Setting quality above 75% often results in a much larger file with little improvement in visual quality." So why is there even an option to go higher than 75% (or rather, why not just call the 75% mark 100%)? Is there a scenario in which the visual quality is likely to improve enough that it's worth the huge file size? 
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jmgarroway

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Posted 11 months ago

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rg

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I think it's a bit like Spinal Tap -- "these go to eleven."  Well, Camtasia goes to 100!

Seriously, I find stuff like "percent quality" less useful than providing data rate.  It would be more helpful to offer a slider or radio buttons for various data rates, with pop-ups that roughly explain/describe quality levels.
(Edited)
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Rick Stone

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LOL, LOVE IT!
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pearsonweb

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Indeed - every time a upload one of my corp training videos rendered in Camtasia to vimeo, it says "Your video could look much better if you gave it the proper resolution" or something like that. In my experience most of my training videos are consumed via mobile device or PC. But we do have occasion where the video is displayed on a 60" HDTV or projected - that's when I feel the 'missing' pixels or compression is noticed. I thought the rule of thumb was "produce at the highest quality/setting possible and let the broadcast device or stream throttle it as necessary" but maybe that's not quite accurate. My coworkers seem obsessed with getting the smallest file size possible but I take the opposite stance. They set their audio to mono instead of stereo and compress the audio to 96kbps and insist the user can't tell the difference between  a 320KB stereo audio and 96KB mono. I've not done official testing but I've always been a quality kind of guy - bandwidth and storage are (relatively) cheap - why not go for the biggest/best production you can get? 
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david

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I agree pearsonweb..  Why slight the audience with a n OK presentation, if a great presentation, including audio, is available?
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rg

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I agree.

In the old days of the web, the recipient's bandwidth was a primary determinant, so if you had a massive stream of video/audio it would cause hiccups while the recipient's computer downloaded more data chunks.  Sometimes a high-rate stream would cause a freeze.  That was why people opted for smaller file sizes.  For playback from a disc or hard drive, a constant (not variable) bit rate was crucial, and on many PCs a rate of 4000 was sufficient for, uhm, reasonable quality.

All of this has evolved.  Now, communication between the browser and the provider can adjust and optimize the data stream.  Screens have higher resolutions and come in ever larger sizes.  Quality can once again be a goal, without sacrificing the ability to play video without freezes.  The obsessions with reducing file size and data rate are no longer requirements (although for most applications, I'd still question whether stereo typically makes any difference -- this ain't The Doors' Soft Parade after all).  While there's an audible difference between 320kbps and 96kbps, most people would not hear a difference between 320 and 192.  Most cannot hear a difference between audio at 44.1 vs 48 sampling rates unless you do an A/B comparison.

Even with all of the advances, if the target audience will be viewing on their phones, I wonder if most people would notice (or care about) the difference between a 3k versus an 11k data stream.

Side note:  Many podcasts stream/download MP3 files with 96kbps to help ensure stability.  The sound is crunchy, but the subscribers keep listening.
(Edited)
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Joe Morgan

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Perfect example pearsonweb
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Dave O'Rourke, Senior Software Engineer

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Sorry, I'm late to this thread.  Bitrate and encoding is a complex topic.  I'll do my best to shed some light on what's going on here.

To answer the question from the OP, the warning is there because we had a lot of people who would push the quality all the way up to 90% or 100% and then complain that they got a much larger file with little improvement in visual quality.  That's expected, because the quality slider is hooked up (inversely) to a constant quantizer parameter. The net effect is that linear increases in the quality % result in an exponential increase in file size.

So why not just remove the upper quality range as an option?  Well, as pointed out in this thread, sometimes users *want* max quality, and don't care about file size.  There are times when that's useful. But note that the visual quality difference between say 85% and 100% is sometimes very slight, yet the file may be *much* bigger.  A larger MP4 file can cause long upload or download times, and in some cases, playback stuttering if the MP4 is placed on a network drive or other drive with slower disk access times.

Now let's talk about YouTube and Vimeo.  When you upload a video to these sites, they are transcoding your video (making multiple copies of your original) at different dimensions and bitrates.  This happens during the "processing" step, which begins immediately after the upload completes. This is done so that they can optimize the viewing experience for many different devices, bandwidths, etc.  So the video you're watching on YouTube isn't actually the same bits you uploaded. Knowing that fact changes things a bit. Since the video coming out of Camtasia isn't the video being downloaded by your viewer, the file size only affects your upload time to YouTube and Vimeo, and this has no effect on the experience of the viewer, because these sites will fix that for you.  So for YouTube and Vimeo, the video and audio quality are the most important things.  The encoding guidelines are given to help you upload videos of high quality.

Ok, onto bitrate.  The bitrate setting on an encoder is a constraint.  It sets a target or max amount of bits (file size) that the encoder is allowed to use for a second of video.  If a section of video hits this cap, the encoder lowers the visual quality for that section in order to meet the bitrate constraint.  If the bitrate is not allowed to vary, and the bitrate is too low, the video may have complex, high motion sections that are blocky or blurry.  Starting from that video, you can't get that quality back. You have to re-produce starting from the original at a higher bitrate so that those sections don't hit the bitrate constraint.  That's why YouTube and Vimeo list bitrates that are on the high side. They don't want you to upload video that's been over compressed, because they can't do anything to fix it.

But there's another way to encode video.  It's called constant quality variable bitrate encoding.  The idea here is to NOT put a bitrate constraint on the encoder.  Instead, we allow the bitrate to vary, as needed, according to the complexity of the video.  This has the desirable effect that the video maintains a similar visual quality throughout, while only using as much file size as is necessary for a particular section of video.  The result is a well compressed video that doesn't get blocky or blurry during any high motion sequences.

This second approach is Camtasia's default for MP4.  For complex sections of the video, it will use a higher bitrate than for less complex sections.  So the content of the video affects the file size.  This is where screen recordings are different than camera footage.  Consider a recording of your screen at 30 frames per sec. Most of the time, the screen is very static and doesn't change much from one frame to the next.  There's a lot of redundant temporal information, and that makes the video highly compressible. The same is not true with real world video that you record with your phone or video camera, especially if there's motion from the camera, or from whatever is being filmed.  This content is less compressible, and generally requires a larger size to maintain the same visual quality.

So why does Vimeo sometimes warn when you upload a video from Camtasia?  Put simply, because the video is smaller than they expect. They look at the file size of the video, and the length, and if it's smaller than a threshold, they guess that the video may be of low visual quality.  But is it? Watch it and decide for yourself. The important thing is that you're uploading something of high visual quality.  Well compressed camera video is going to be much larger than well compressed screen video. Their threshold probably works well for camera video, but not to low-motion screen video.

Sorry for the long post.  As I said in the beginning, bitrate is a complicated topic.  If you've read this far, I hope you've found this post helpful.

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jmgarroway

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I did find it helpful! Thank you very much :-)