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blachanc
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Future module Based on bcm2711: Question about H264 decoding spec

Thu Apr 30, 2020 5:40 am

Hi,

Quick question (planning in advance for a possible compute module using the bcm2711)
I am looking for a clarificartion about the bcm2711 page:

https://www.raspberrypi.org/documentati ... /README.md

Code: Select all

Multimedia: 
H.265 (4Kp60 decode); 
H.264 (1080p60 decode, 1080p30 encode);
OpenGL ES, 3.0 graphics
Can I assume, that based on this spec, (if the foundation would produce a module based on the bcm2711),
it could not decode a 4K source in H264 , but only decode a 4K source in H265?

Thank you,

Ben
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gsh
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Thu Apr 30, 2020 5:48 am

That's correct
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blachanc
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Thu Apr 30, 2020 4:36 pm

Gordon,

Thanks for confirming this.
gsh wrote:
Thu Apr 30, 2020 5:48 am
That's correct
So many HW devices discard H264 4KP60 decode in favor of H265 decode.
That would be an intersting "off topic" discussion.

Ben
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Fri May 01, 2020 4:39 pm

Side note... NEC is bring out a line of commercial displays this summer (nominal launch in August) that is supposed to support a CM4, internally. Whether on not there will be a CM4 available when the monitors launch isn't known out here in the bleachers at this point. Stay tuned...

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Re: Future module Based on bcm2711: Question about H264 decoding spec

Fri May 01, 2020 4:44 pm

blachanc wrote:
Thu Apr 30, 2020 4:36 pm
So many HW devices discard H264 4KP60 decode in favor of H265 decode.
For the Pi 4, it is more that the H.264 codec is the same one from before so has the existing limitations. A new 4K capable H.265 decoder was added.

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Re: Future module Based on bcm2711: Question about H264 decoding spec

Mon May 04, 2020 2:49 pm

trejan wrote:
Fri May 01, 2020 4:44 pm
blachanc wrote:
Thu Apr 30, 2020 4:36 pm
So many HW devices discard H264 4KP60 decode in favor of H265 decode.
For the Pi 4, it is more that the H.264 codec is the same one from before so has the existing limitations. A new 4K capable H.265 decoder was added.
If I read correctly (or maybe there is a typo on element14 spec):

The H264 specs of the PI4 processor (HDp60) are superior to the H264 specs of the actual PI3+ processor (HDp30):

https://www.element14.com/community/com ... ute-module


Broadcom BCM2837B0, Cortex-A53 64-bit SoC @ 1.2GHz
1Gbyte LPDDR2 SDRAM
Memory Options: 8 Gbytes, 16 Gbytes, 32 Gbytes eMMC Flash
Multimedia: H.264, MPEG-4 decode (1080p30), H.264 encode (1080p30), OpenGL ES 1.1, 2.0 graphics
SD card support: The CM3+ Lite brings the SD card interface to the module pins so a user can connect this to either an eMMC or SD card.
Environment: Operating temperature, -20° to +70°C
35u hard gold plated IO Pins
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Mon May 04, 2020 3:00 pm

blachanc wrote:
Mon May 04, 2020 2:49 pm
trejan wrote:
Fri May 01, 2020 4:44 pm
blachanc wrote:
Thu Apr 30, 2020 4:36 pm
So many HW devices discard H264 4KP60 decode in favor of H265 decode.
For the Pi 4, it is more that the H.264 codec is the same one from before so has the existing limitations. A new 4K capable H.265 decoder was added.
If I read correctly (or maybe there is a typo on element14 spec):

The H264 specs of the PI4 processor (HDp60) are superior to the H264 specs of the actual PI3+ processor (HDp30):

https://www.element14.com/community/com ... ute-module


Broadcom BCM2837B0, Cortex-A53 64-bit SoC @ 1.2GHz
1Gbyte LPDDR2 SDRAM
Memory Options: 8 Gbytes, 16 Gbytes, 32 Gbytes eMMC Flash
Multimedia: H.264, MPEG-4 decode (1080p30), H.264 encode (1080p30), OpenGL ES 1.1, 2.0 graphics
SD card support: The CM3+ Lite brings the SD card interface to the module pins so a user can connect this to either an eMMC or SD card.
Environment: Operating temperature, -20° to +70°C
35u hard gold plated IO Pins
It's the same H264 block, so performance is the same per clock. Of course, the clocks can be faster on the Pi4, so there is a bit of extra performance, but resolution limits stay the same.
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Mon May 04, 2020 3:29 pm

What jamesh said ^
blachanc wrote:
Mon May 04, 2020 2:49 pm
The H264 specs of the PI4 processor (HDp60) are superior to the H264 specs of the actual PI3+ processor (HDp30):
One oddity is that the CM3+ SoC isn't the same as a 3B+ SoC as the default CM3+ firmware configuration sets the clock slower than the 3B+. The h264 block core defaults to 250MHz on a CM3+ which isn't enough for 1080p60. The Pi 3 onwards increased that clock so it can do 1080p60. https://www.raspberrypi.org/documentati ... locking.md has a table of default clock frequencies but is missing data for the Compute Modules.

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blachanc
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Re: Future module Based on bcm2711: Question about H264 decoding spec

Mon May 04, 2020 3:52 pm

jamesh/trejan,

Many Thanks to both of you for your clarifications !!
Jamesh:
It's the same H264 block, so performance is the same per clock. Of course, the clocks can be faster on the Pi4, so there is a bit of extra performance, but resolution limits stay the same.
trejan:
The h264 block core defaults to 250MHz on a CM3+ which isn't enough for 1080p60. The Pi 3 onwards increased that clock so it can do 1080p60.

Ben
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http://www.raspberrypi.org/forums/viewtopic.php?f=62&t=70191

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