5 ms·

How good is the performance? Is 4K60 on a phone possible? 1080p60? Hard to find numbers on this

by WithinReason 5y ago

iso1631 5y ago
Trying to imagine how close you would have to be to the screen to tell the difference between 1080 and 4k...
- true_religion 5y ago
  Surely, sitting in front of a laptop or iMac would make it easy to tell.
  - iso1631 5y ago
    "on a phone" SMPTE suggest that 4k for viewing is only worthwhile for people with 20/20 vision once the viewing angle increases beyond 30 degrees. I'm currently looking at a 40cm wide screen, I'm 80cm away from it, which is about 30 degrees. For my phone to fill that amount of space it would have to be about 10cm in front of my eyes due to binocular vision (if I just use one eye it's a bit further When I watch something on my phone it's typically 50cm away, about 15-20 degrees viewing. 720p is more than enough at that size, 1080p if you have particularly good eyesight.
- WithinReason 5y ago
  It's hard to tell for uncompressed, but easy for compressed YouTube videos
  - LeFantome 5y ago
    Compressed by what? Are you just talking about videos you record on your phone? I do not know what phone you have but an iPhone 12 ( as an example ) is under 1300 pixels on the short dimension. So you are not getting much more than 1080 pixels no matter what. It seems any experiential difference would have more to do with compression quality than with resolution. Speaking for myself, I do not think I could tell the difference between 4K and 1080p on a phone ( on a decent AV1 clip ).
  - wyldfire 5y ago
    But doesn't YouTube negotiate a "channel sized" rate? It seems like it switches between bitrates based on what you can tolerate. All of this is to say that it seems like a tough-to-nail-down metric to evaluate.
  - iso1631 5y ago
    So you're saying that a given 4k source compressed to Xmbit will look better if it's not downscaled to 1080p before compression, but instead downscaled by the display (I don't believe there are any phones with a 2160 line display)?
    - WithinReason 5y ago
      4K YouTube videos have a higher bitrate than 1080p videos
    - tedunangst 5y ago
      What they're saying is that a 1080p source upscaled to 4K and then uploaded to youtube and then downscaled by the client to a 1080p screen will look better than a 1080p upload because it has more bits.
      - iso1631 5y ago
        That's nothing to do with the codec or the resolution
        Dylan16807 5y ago
        The reason it looks better isn't directly codec or resolution. But it does mean that there are reasons to want 4K playback on a phone.
  - Rebelgecko 5y ago
    I always assumed that for streaming sites bitrate was a bigger factor
    - iso1631 5y ago
      Of course it is, a 1080p video at 10mbit will almost always look better than a 4k video at 1mbit, and a 4k video at 10mbit will almost always look better than a 1080p video at 1mbit. The far more interesting question is if you accept you have Xmbit to play with, what is better on a given platform (screen size, resolution, viewing situation, how well compression works, how much battery is used in decoding, etc)
    - brigade 5y ago
      And bitrate goes up for 4k tiers. Even if bitrate only doubles for 4x the amount of pixels, that'll probably look better with modern codecs (depending on where in the quantization curve you are), and most services use at least 3x the bitrate for 4k over 2k, across the same codec.
throw0101a 5y ago
I think that for most of these libraries software-only performance is a moot point: the library is there for other software to use to be able to parse the files, and the library/decoder will simply offload the heavy compute to the (hopefully eventually-available) decoding hardware instructions. To a certain extent it's just a place holder so folks can start writing software against it so that when the CPU vendors ship everyone can hit the ground running.
- WithinReason 5y ago
  Wouldn't that only be true of the reference encoder libaom? This is the description the dav1d page gives: dav1d is the fastest AV1 decoder on all platforms :) Targeted to be small, portable and very fast. Since they use the word fast twice I was wondering how fast.
  - ZeroGravitas 5y ago
    I'll try to dig up the slide where they demonstrated it, but basically faster at equal quality than any software decoder of any codec. Which is cool, but if you have hardware decode then you may not care, though software decode gets used in all sorts of weird places that you might not expect.
    - WithinReason 5y ago
      Of any codec? Are you sure?
      - ZeroGravitas 5y ago
        Yeah, the key is that newer generations of codecs use more time to encode, but often the decode time goes up less than the encode time. Combine that with greater design for parallelism and you find yourself in the slightly counterintuitive situation where decoding the same quality of video is faster in the newest codecs (at the one time cost of longer encodes). I dont think it was one single slide I was thinking of but you can for example find comparisons of vp8, vp9, h264 by the same videolan/ffmpeg devs that demonstrate this general principle, the decode fps is surprisingly flat between software decodes of different codec families and generations. The earlier generations often hit bottlenecks though, I think ffmpeg VP9 decode (built by the same people as dav1d) was the leader for a while but hits a wall at 4 cores due to format limitations. HEVC and especially dav1d have some gains when you can throw a modern amount of cores at it, and even phones often have 8.
daneel_w 5y ago
It's bad. As a reference, I tried decoding a measly 2 mbit/s test clip on an older Core 2 Duo MacBook Pro (which has no issues playing back the same in H.264 purely with software decoding), and it stuttered a lot. I don't see this thing taking off until there's decent GPU acceleration in place. "Fast decoder" is highly relative.
- clouddrover 5y ago
  I tried decoding a measly 2 mbit/s AV1 test clip on a 2014 MacBook Pro with a 2.2 GHz Quad-Core Intel Core i7 and it was buttery smooth.
  - daneel_w 5y ago
    So is an H.264/H.265 video clip at 5 or even 10 mbit/s on my 4 years old iPhone, at about 2 watts of power consumption instead of 35 watts. Can you see the advantage? I like open and free standards, and I dislike royalties, but the political aspect is best foregone when one of the alternatives really is objectively so much better for everyone.
    - clouddrover 5y ago
      One of the alternatives is clearly not objectively so much better for everyone. If they were so much better then VP9 and AV1 wouldn't exist. Here's what video streamers say: https://youtube-eng.googleblog.com/2015/04/vp9-faster-better-buffer-free-youtube.html https://youtube-eng.googleblog.com/2015/04/vp9-faster-better... https://engineering.fb.com/2018/04/10/video-engineering/av1-beats-x264-and-libvpx-vp9-in-practical-use-case/ https://engineering.fb.com/2018/04/10/video-engineering/av1-... https://netflixtechblog.com/netflix-now-streaming-av1-on-android-d5264a515202 https://netflixtechblog.com/netflix-now-streaming-av1-on-and... https://medium.com/netflix-techblog/bringing-av1-streaming-to-netflix-members-tvs-b7fc88e42320 https://medium.com/netflix-techblog/bringing-av1-streaming-t... https://bitmovin.com/bitmovin-improves-av1-video-encoding/ https://bitmovin.com/bitmovin-improves-av1-video-encoding/ https://blog.webex.com/video-conferencing/cisco-leap-frogs-h-264-video-collaboration-with-real-time-av1-codec/ https://blog.webex.com/video-conferencing/cisco-leap-frogs-h... https://blog.webex.com/engineering/the-av1-video-codec-comes-to-webex/ https://blog.webex.com/engineering/the-av1-video-codec-comes... Your problem is fundamentally an emotional one. Now that you suspect Device X will perform poorly at Task Y you feel buyer's remorse. Try not to worry about it so much. Computer hardware will continue to be made obsolete by more demanding software for quite some time yet.
ksec 5y ago
>Is 4K60 on a phone possible? Depends on SoC. A15? or low end UniSoC SoC? But generally speaking a modern Smartphone should be able to play 1080P 25fps 1mbps AV1 video on their phone without dropping frames. You will just be burning away your battery life.

How good is the performance? Is 4K60 on a phone possible? 1080p60? Hard to find numbers on this

iso1631 5y ago

Trying to imagine how close you would have to be to the screen to tell the difference between 1080 and 4k...

true_religion 5y ago
Surely, sitting in front of a laptop or iMac would make it easy to tell.
- iso1631 5y ago
  "on a phone" SMPTE suggest that 4k for viewing is only worthwhile for people with 20/20 vision once the viewing angle increases beyond 30 degrees. I'm currently looking at a 40cm wide screen, I'm 80cm away from it, which is about 30 degrees. For my phone to fill that amount of space it would have to be about 10cm in front of my eyes due to binocular vision (if I just use one eye it's a bit further When I watch something on my phone it's typically 50cm away, about 15-20 degrees viewing. 720p is more than enough at that size, 1080p if you have particularly good eyesight.
WithinReason 5y ago
It's hard to tell for uncompressed, but easy for compressed YouTube videos
- LeFantome 5y ago
  Compressed by what? Are you just talking about videos you record on your phone? I do not know what phone you have but an iPhone 12 ( as an example ) is under 1300 pixels on the short dimension. So you are not getting much more than 1080 pixels no matter what. It seems any experiential difference would have more to do with compression quality than with resolution. Speaking for myself, I do not think I could tell the difference between 4K and 1080p on a phone ( on a decent AV1 clip ).
- wyldfire 5y ago
  But doesn't YouTube negotiate a "channel sized" rate? It seems like it switches between bitrates based on what you can tolerate. All of this is to say that it seems like a tough-to-nail-down metric to evaluate.
- iso1631 5y ago
  So you're saying that a given 4k source compressed to Xmbit will look better if it's not downscaled to 1080p before compression, but instead downscaled by the display (I don't believe there are any phones with a 2160 line display)?
  - WithinReason 5y ago
    4K YouTube videos have a higher bitrate than 1080p videos
  - tedunangst 5y ago
    What they're saying is that a 1080p source upscaled to 4K and then uploaded to youtube and then downscaled by the client to a 1080p screen will look better than a 1080p upload because it has more bits.
    - iso1631 5y ago
      That's nothing to do with the codec or the resolution
      - Dylan16807 5y ago
        The reason it looks better isn't directly codec or resolution. But it does mean that there are reasons to want 4K playback on a phone.
- Rebelgecko 5y ago
  I always assumed that for streaming sites bitrate was a bigger factor
  - iso1631 5y ago
    Of course it is, a 1080p video at 10mbit will almost always look better than a 4k video at 1mbit, and a 4k video at 10mbit will almost always look better than a 1080p video at 1mbit. The far more interesting question is if you accept you have Xmbit to play with, what is better on a given platform (screen size, resolution, viewing situation, how well compression works, how much battery is used in decoding, etc)
  - brigade 5y ago
    And bitrate goes up for 4k tiers. Even if bitrate only doubles for 4x the amount of pixels, that'll probably look better with modern codecs (depending on where in the quantization curve you are), and most services use at least 3x the bitrate for 4k over 2k, across the same codec.

throw0101a 5y ago

I think that for most of these libraries software-only performance is a moot point: the library is there for other software to use to be able to parse the files, and the library/decoder will simply offload the heavy compute to the (hopefully eventually-available) decoding hardware instructions. To a certain extent it's just a place holder so folks can start writing software against it so that when the CPU vendors ship everyone can hit the ground running.

WithinReason 5y ago
Wouldn't that only be true of the reference encoder libaom? This is the description the dav1d page gives: dav1d is the fastest AV1 decoder on all platforms :) Targeted to be small, portable and very fast. Since they use the word fast twice I was wondering how fast.
- ZeroGravitas 5y ago
  I'll try to dig up the slide where they demonstrated it, but basically faster at equal quality than any software decoder of any codec. Which is cool, but if you have hardware decode then you may not care, though software decode gets used in all sorts of weird places that you might not expect.
  - WithinReason 5y ago
    Of any codec? Are you sure?
    - ZeroGravitas 5y ago
      Yeah, the key is that newer generations of codecs use more time to encode, but often the decode time goes up less than the encode time. Combine that with greater design for parallelism and you find yourself in the slightly counterintuitive situation where decoding the same quality of video is faster in the newest codecs (at the one time cost of longer encodes). I dont think it was one single slide I was thinking of but you can for example find comparisons of vp8, vp9, h264 by the same videolan/ffmpeg devs that demonstrate this general principle, the decode fps is surprisingly flat between software decodes of different codec families and generations. The earlier generations often hit bottlenecks though, I think ffmpeg VP9 decode (built by the same people as dav1d) was the leader for a while but hits a wall at 4 cores due to format limitations. HEVC and especially dav1d have some gains when you can throw a modern amount of cores at it, and even phones often have 8.

daneel_w 5y ago

It's bad. As a reference, I tried decoding a measly 2 mbit/s test clip on an older Core 2 Duo MacBook Pro (which has no issues playing back the same in H.264 purely with software decoding), and it stuttered a lot. I don't see this thing taking off until there's decent GPU acceleration in place. "Fast decoder" is highly relative.

clouddrover 5y ago
I tried decoding a measly 2 mbit/s AV1 test clip on a 2014 MacBook Pro with a 2.2 GHz Quad-Core Intel Core i7 and it was buttery smooth.
- daneel_w 5y ago
  So is an H.264/H.265 video clip at 5 or even 10 mbit/s on my 4 years old iPhone, at about 2 watts of power consumption instead of 35 watts. Can you see the advantage? I like open and free standards, and I dislike royalties, but the political aspect is best foregone when one of the alternatives really is objectively so much better for everyone.
  - clouddrover 5y ago
    One of the alternatives is clearly not objectively so much better for everyone. If they were so much better then VP9 and AV1 wouldn't exist. Here's what video streamers say: https://youtube-eng.googleblog.com/2015/04/vp9-faster-better-buffer-free-youtube.html https://youtube-eng.googleblog.com/2015/04/vp9-faster-better... https://engineering.fb.com/2018/04/10/video-engineering/av1-beats-x264-and-libvpx-vp9-in-practical-use-case/ https://engineering.fb.com/2018/04/10/video-engineering/av1-... https://netflixtechblog.com/netflix-now-streaming-av1-on-android-d5264a515202 https://netflixtechblog.com/netflix-now-streaming-av1-on-and... https://medium.com/netflix-techblog/bringing-av1-streaming-to-netflix-members-tvs-b7fc88e42320 https://medium.com/netflix-techblog/bringing-av1-streaming-t... https://bitmovin.com/bitmovin-improves-av1-video-encoding/ https://bitmovin.com/bitmovin-improves-av1-video-encoding/ https://blog.webex.com/video-conferencing/cisco-leap-frogs-h-264-video-collaboration-with-real-time-av1-codec/ https://blog.webex.com/video-conferencing/cisco-leap-frogs-h... https://blog.webex.com/engineering/the-av1-video-codec-comes-to-webex/ https://blog.webex.com/engineering/the-av1-video-codec-comes... Your problem is fundamentally an emotional one. Now that you suspect Device X will perform poorly at Task Y you feel buyer's remorse. Try not to worry about it so much. Computer hardware will continue to be made obsolete by more demanding software for quite some time yet.

ksec 5y ago

>Is 4K60 on a phone possible? Depends on SoC. A15? or low end UniSoC SoC? But generally speaking a modern Smartphone should be able to play 1080P 25fps 1mbps AV1 video on their phone without dropping frames. You will just be burning away your battery life.