Broadcom SoCs

Discussion in 'Mobile Devices and SoCs' started by ToTTenTranz, Feb 13, 2014.

  1. ToTTenTranz

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    From what I understood, the new H265 decoding capabilities come from the much higher FPU performance of the Cortex A53 cores. Which means it's now capable of some software decoding, nothing else.
     
  2. tuna

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    The RP2 can't do DVD quality MPEG2 in software/CPU (I tried), so I fail to see how the RP3 can do H265 on the CPU. But I have been wrong before....
     
  3. Blazkowicz

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    Was your decoding software badly compiled or single-threaded? Software scaling instead of using the GPU in some way?
    DVD decoding used to require a low clock Pentium III or Athlon, I reckon a Pi 1 may be a bit too weak but that Pi 2 has enough CPU resources.
     
  4. tuna

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    I believe that x86 MPEG2 decoding have been quite heavily optimized using assembly and MMX/SSE functions. The same is not true for the ARM core in the RP2 it seems. But I am to lazy to look into the ffmpeg code right now....
     
  5. ToTTenTranz

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    I'm digging up this thread because with yesterday's announcement of the Raspberry Pi 4 that brings a whole new SoC from Broadcom, the BCM2711:

    - 28nm
    - 4-core Cortex A72 @1.5GHz (is there any other A72 implementation on 28nm?)
    - 32bit single-channel LPDDR4 (assumed by me because there's only one off-chip memory module on the PCB)
    - Videocore VI GPU @ 500MHz
    - H265 4K60 video decoder


    There are pretty much no details about the new GPU, except for clock speed and the fact that it runs OpenGL ES 3.0 (i.e. not Vulkan).
    Is this the same Videocore IV GPU that was in the older SoCs but with higher frequency and a new video decoder block? AFAIK the Pi3 had a Videocore IV at 300MHz.
    If so, it seems a bit problematic for the Raspberry Pi Foundation that the Videocore line was practically axed around 8 years ago yet they keep pushing the same 3D core on new SoCs.
    The Pi Foundation claims they're putting the open source aspect of the GPU above all else, but does that really matter to the point of stagnating the 3D performance for so many years, as well as not supporting any GPGPU or machine learning APIs?


    It still seems to be a fantastic SoC for light web-browsing, office work, home multimedia and development for education at an incredible price.
     
  6. tuna

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  7. mczak

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    Don't insult my smartphone (SD 650 powered)! The frequency though seems to be quite low, the SD 650 already reached 1.8Ghz (but not sure it's the same 28nm tech). Although I guess the SD 650 has much better power / clock management (it also only has 2 A72 cores apart from the 4 A53 ones, but the SD 652/653 have four A72 cores too, albeit according to the benchmarks I've seen they can't really make too much use of the additional cores indeed).
    I'm kind of surprised though they went with the old A72 design for this seemingly new chip (well my smartphone already gets no more android version updates...), since while the A73 (on iso-process) doesn't really do much for performance, it's smaller and more power efficient. (But maybe it can't be ported easily to 28nm, since for this one I'm not aware of any 28nm implementations?)

    edit: mediatek also has 28nm Cortex A72 - MT8173 (and more).
    Outside of smartphones, I wouldn't be surprised if there's lots of chips you've never heard about using Cortex A72 / 28nm (quickly I found the RK3399).
     
    #47 mczak, Jun 25, 2019
    Last edited: Jun 26, 2019
  8. ToTTenTranz

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    Oh how could I forget the greatest mid-range smartphone chip ever to exist on 28nm?
    I got my both my wife, my father and a couple of friends to get a Redmi Note 3 because of that chip.

    Then perhaps the 28nm process is the reason they went with the older A72. ARM may not provide libraries for the newer cores on the older process.
     
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  9. BRiT

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    I think they were saying around 8 Watts usage for the Chip, not counting powering external devices via the USB connections. Does that sound about right?
     
  10. kalelovil

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    https://www.raspberrypi.org/magpi/raspberry-pi-4-specs-benchmarks/

    7.6 watts at load according to the above benchmarks.

    The only 3D benchmark shows a 52% fps gain so that is probably right.
     
  11. BRiT

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    Not too bad at all, Pi 4 @ 7.6 Watts vs Pi 3B+ @ 6.4 Watts under load. It's definitely nothing like the first takes some had going strictly off the power supply / wall-wart specs.

    Interesting browse through the benchmarks. Thanks for posting the link. Nice improvements all around, making it suitable for even more projects and seems like booting from external USB wouldn't be a bottleneck anymore.
     
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