I believe this is to some degree due to chroma key subsampling, where in a 4k stream you will only have 1080p worth of light intensity encoded (cluster of 4px). So if you play an 8k stream and downscale to 4k you actually have full chroma (1:1).
There could of course be other factors involved as well but this is definitely a pretty big contributor.
You have chroma and luma the wrong way around, chroma is color and luma is light intensity. Chroma is still the thing being subsampled.
I've never really noticed effects from chroma subsampling so my guess would be the bitrate just being better with the higher resolution. Also "full res->compress->downsample" might be more efficient than "full res->downsample->compress" since downsampling is a (really bad) form of lossy compression as well.
Similarly, 4K video looks much better on a 1080p screen than a 1080p video. A youtuber posted a comparison, its easy to see even in a still image. Its all in their encoding algorithm.
> That shouldn’t be noticeable if the 4K stream was encoded properly.
I don't think this is true. At some point there are diminishing returns. At some point if the 4k video has twice the bitrate it is going to have more information available. Some will be lost in the down sampling but it isn't "improper" to end up with more data on the screen.
It is true that YouTube bitrates are pretty "conservative" for the resolution but I don't think that is "improper" it is just a tradeoff based on common device an internet speeds. They could be more bandwidth efficient if they did a custom transcode for each user's screen size and bandwidth but that is infeasible. So it is fine that some users will not be able to stream the 4k transcode on their 4k screen and will need to use the 2k stream and some users will have extra bandwidth on their 1080p screen so will stream the 2k version for better quality. The goal isn't to be perfect for each device but to be good on average.
It's interesting to see how tiny Netflix mobile download files are.
200MB - 300MB for full-length movies, ~150MB for series episodes.
This is on "Standard quality", but still.
After some quick Googling (grain of salt) I see that a standard DVD of 4.7GB tends go have (usual encoding) up to 135 min of 480p video. That's a big difference! Even when considering that modern encoding might be more efficient. It is lossy compression, and the lossyness seems to be cranked way up.
DVDs of movies were actually dual layer, and had ~9GB capacity. I remember this distinctly because to copy a movie rental to a DVD-R you had to use a program like DVD Shrink so you could strip out all the extra features and compress the video a bit more to get it to be under 4.7GB
This will depend on the movie and dual layer was more an exception than the norm. Rarely, a movie could be spread across multiple discs as well. Most typically for the extras but sometimes just to fit longer movies in decent quality.
In days of yore before upscaling was computationally practical a better standard was PAL region DVD's that were encoded from master (be that hires digital tape or direct from film).
In PAL regions, the PAL signal uses 625 signal lines, of which 576 (known as 576i signal) appear as visible lines on the television set, whereas NTSC formatted signal uses 525 lines, of which 480 appear visibly (480i).
In PAL video, every second line has the phase of the color signal reversed, which leads to the signals flattening out the frequency between the lines.
Effectively what this means is that damage to the signal appears as errors in saturation (level of color) rather than hue (shade of color) as it would appear in NTSC video, leading to a higher-fidelity picture of the original studio version.
The difference is bitrate. DVDs were 10 mbit of MPEG-2 while YouTube 480p is 2.5mbit of h264 (or transcodes thereof). These are different encodings so it's not a 1 to 1 comparison of bitrates as h264 is more efficient, but this article indicates that you'd need 4mbit of h264 (which is closer to that YouTube allocates to 720p video) to match the perceived quality of 10mbit of MPEG-2: https://streaminglearningcenter.com/articles/h264-vs-mpeg-2-...
I am not sure where you get the 2.5Mbps and 4 Mbps number from because those are very high numbers for streaming ( or even for torrent downloading ) for those resolution and Youtube dont use any where near those number. A quick check shows Youtube only uses around 600Kbps on 720P video. And anywhere between 1.5 to 1.8Mbps for 1080P content. I am guessing their relatively low quality compared to their bitrate is because their encoding process optimise for encoding time rather than quality per bit simply because of the volume they have per day.
They will then transcode it to h265, or webm which uses even less bandwidth, but I'm giving them the benefit of the doubt here and assuming they target their transcoding setup to preserve as much quality as they recommend providing them.
And of course this is VBR not CBR, so some scenes will use less.
4mbps is the linked article description of where h264 matches DVD quality. Yes, 4mbps is more than most streaming sites will give for 480p. This does mean that most streaming sites are inferior to DVDs at 480p. The fact that most streaming sites use less bitrate than a DVD-equivalent quality is therefore not surprising, giving that people have noticed that exact fact.
Streaming sites do not pick their bitrate to maximise quality given a fixed maximum filesize, so it's not surprising that they choose a lower bitrate (and therefore lower quality) than DVDs. They're instead optimizing for things like their server costs, time to playback start, or the ability to perform uninterrupted playback over the internet connection of users resorting to these lower resolution settings.
Ok, sure, they also produce extra h264 files at various resolutions and quality levels. Transcoding can't invent quality that wasn't there in the input, so I don't see how that changes anything. That 2.5mbit/s upload they accept is therefore the ceiling.
Honestly this is one of the best monetization schemes I can think of for YouTube. It's an advantage that doesn't take away anything for non-premium users, and it improves the main functionality of the service. I sincerely hope they can do more like this instead of increasing ad lengths for non-premium users!
It's really strange though when they offer higher resolution streams for free. So this only really helps for videos that are 1080p. In most cases watching 2k or 4k even on a 1080p monitor will result in better quality (although maybe less bandwidth efficient).
Eh, it's more of a boiling the frog situation. The quality for 1080p video has gone down a LOT over the past 5 years. It's hard to notice for general-purpose videos, but speciality videos (in my case, Starcraft2 replays) with non-standard content or high complexity (some slow motion videos of chaotic systems) just immediately collapse into noise.
It's been nearly impossible to see invisible units in Starcraft2 replays on 1080p for a long time now, but that didn't used to be the case. YouTube has spent a lot on improving the compression algorithms to save money, and they've maintained 90% of the quality for most content, but the edge cases have seen 50%+ drop in visible quality. 4k completely fixes these problems and has very conservative (expensive) compression, but too many content creators still don't take advantage of that and produce only in 1080p.
When 1080p came out on YouTube, it was much, much less compressed than it is now. So they did take it away for non-premium users. They just did it slowly over a long timescale.
Is this different from selecting a higher resolution stream (with increased bitrate) and downscaling it on a 1080p display? If not, will they hide 1440+p options behind a paywall as well?
Most creators upload at 1080p, and YouTube has always given bitrate recommendations to match their service. Even with updated documentation, I'm expecting lots of people using their existing encoding presets for future 1080p uploads that can't benefit from this paywalled upgrade.
You can grab the enhanced bitrate 1080p option with yt-dlp.
It's not better than the 1440p or 4K downscaled. The main use I see for it is for videos that were only uploaded in 1080p in the first place, and so they don't have a 1440p or 4K option.
But even then, I am not seeing a very big difference at all between the regular 1080p and enhanced 1080p.
1. If you are bandwidth limited the high bitrate version should be a bit more efficient than the higher resolution (as it isn't wasting space on details that will be lost in the downscaling).
2. For videos that are uploaded in 1080p it will be the best quality available.
So it does seem like a pretty niche benefit. Maybe if you have a 1080p phone it can be worth it for the reduced resource usage and better battery life? But with many channels starting to upload in 4k it does seem like a very minor improvement in most cases.
Higher Bitrate but doesn't say the actual bitrate.
It also doesn't mention about Codec. I assume it is still H.264? Or could it be HEVC given Google already pays the maximum cap on royalty for their Pixel Phone, tablet or other Appliance.
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[ 2.4 ms ] story [ 41.1 ms ] threadI feel like streaming services compress their streams so hard that the resolution indicators become meaningless.
That shouldn’t be noticeable if the 4K stream was encoded properly.
There could of course be other factors involved as well but this is definitely a pretty big contributor.
I've never really noticed effects from chroma subsampling so my guess would be the bitrate just being better with the higher resolution. Also "full res->compress->downsample" might be more efficient than "full res->downsample->compress" since downsampling is a (really bad) form of lossy compression as well.
I don't think this is true. At some point there are diminishing returns. At some point if the 4k video has twice the bitrate it is going to have more information available. Some will be lost in the down sampling but it isn't "improper" to end up with more data on the screen.
It is true that YouTube bitrates are pretty "conservative" for the resolution but I don't think that is "improper" it is just a tradeoff based on common device an internet speeds. They could be more bandwidth efficient if they did a custom transcode for each user's screen size and bandwidth but that is infeasible. So it is fine that some users will not be able to stream the 4k transcode on their 4k screen and will need to use the 2k stream and some users will have extra bandwidth on their 1080p screen so will stream the 2k version for better quality. The goal isn't to be perfect for each device but to be good on average.
200MB - 300MB for full-length movies, ~150MB for series episodes. This is on "Standard quality", but still.
After some quick Googling (grain of salt) I see that a standard DVD of 4.7GB tends go have (usual encoding) up to 135 min of 480p video. That's a big difference! Even when considering that modern encoding might be more efficient. It is lossy compression, and the lossyness seems to be cranked way up.
The movie producers would try to hide it by placing the layer change in a scene change, but I often still noticed it.
They will then transcode it to h265, or webm which uses even less bandwidth, but I'm giving them the benefit of the doubt here and assuming they target their transcoding setup to preserve as much quality as they recommend providing them.
And of course this is VBR not CBR, so some scenes will use less.
4mbps is the linked article description of where h264 matches DVD quality. Yes, 4mbps is more than most streaming sites will give for 480p. This does mean that most streaming sites are inferior to DVDs at 480p. The fact that most streaming sites use less bitrate than a DVD-equivalent quality is therefore not surprising, giving that people have noticed that exact fact.
Streaming sites do not pick their bitrate to maximise quality given a fixed maximum filesize, so it's not surprising that they choose a lower bitrate (and therefore lower quality) than DVDs. They're instead optimizing for things like their server costs, time to playback start, or the ability to perform uninterrupted playback over the internet connection of users resorting to these lower resolution settings.
That is for uploading. They will transcode your H.264 file when you upload it regardless of bitrate.
And your original claims of YouTube using 2.5Mbps and 4Mbps. Go and find me clip with those bitrate?
Here is Disney+ stream vs a Disc 1:1 copy:
https://nicko88.com/misc/compare/Ant%20Man%20Quantumania/
https://nicko88.com/misc/compare/Avatar%20The%20Way%20of%20W...
Streaming looks only slightly marginally worse IMO.
"and Google seems aware of the responsibility it shoulders running one of the best entertainment apps out there. "
What? Get to the point. Google seems aware that it runs YouTube. Yes I'm sure they are.
I mean, yeah. It’s how most content writers are paid. And it’s also how the OpenAI API they use is paid (by the token).
Completely agree and its been super annoying to me that 1080p was compressed so dang aggressively in the past few years.
I have some yt-dlp copies of videos that I grabbed a couple years ago.
If I go and download them again today from the same video URL, the quality is worse when I compare frames from them directly to each other.
It's been nearly impossible to see invisible units in Starcraft2 replays on 1080p for a long time now, but that didn't used to be the case. YouTube has spent a lot on improving the compression algorithms to save money, and they've maintained 90% of the quality for most content, but the edge cases have seen 50%+ drop in visible quality. 4k completely fixes these problems and has very conservative (expensive) compression, but too many content creators still don't take advantage of that and produce only in 1080p.
When 1080p came out on YouTube, it was much, much less compressed than it is now. So they did take it away for non-premium users. They just did it slowly over a long timescale.
Most creators upload at 1080p, and YouTube has always given bitrate recommendations to match their service. Even with updated documentation, I'm expecting lots of people using their existing encoding presets for future 1080p uploads that can't benefit from this paywalled upgrade.
It's not better than the 1440p or 4K downscaled. The main use I see for it is for videos that were only uploaded in 1080p in the first place, and so they don't have a 1440p or 4K option.
But even then, I am not seeing a very big difference at all between the regular 1080p and enhanced 1080p.
1. If you are bandwidth limited the high bitrate version should be a bit more efficient than the higher resolution (as it isn't wasting space on details that will be lost in the downscaling).
2. For videos that are uploaded in 1080p it will be the best quality available.
So it does seem like a pretty niche benefit. Maybe if you have a 1080p phone it can be worth it for the reduced resource usage and better battery life? But with many channels starting to upload in 4k it does seem like a very minor improvement in most cases.
--extractor-args "youtube:player_client=default,ios"
to the command. The ID for the enhanced bitrate 1080p is 616.
Checked 4K one https://www.youtube.com/watch?v=pUm5B-5uQik "FIRST WIN IN THE SW20!!! MR2 Championship Brands Hatch 2023" DannyDC2
Now this is somewhat more interesting. IOS API unlocks higher bitrate m3u8 tracks for all resolutions, even 4K goes from 25 to 28Mbit.It also doesn't mention about Codec. I assume it is still H.264? Or could it be HEVC given Google already pays the maximum cap on royalty for their Pixel Phone, tablet or other Appliance.