zervanko
Posts: 14
Joined: Sat Jun 23, 2018 6:36 pm

What is the true specifications of Raspberry Pi 3 Model B's GPU?

Mon Jul 02, 2018 12:56 pm

I've found three versions of Raspberry Pi 3 Model B's GPU specifications:
1) https://elinux.org/RPi_Hardware , https://bits4device.wordpress.com/2017/ ... spberry-pi , etc:
Broadcom VideoCore IV, OpenGL ES 2.0,OpenVG 1080p60 H.264 high-profile encode/decode, 400 MHz
2) https://docs-emea.rs-online.com/webdocs ... 4ba5fd.pdf
Dual Core VideoCore IV® Multimedia Co-Processor. Provides Open GL
ES 2.0, hardware-accelerated OpenVG, and 1080p30 H.264 high-profile
decode.
Difference (only 30 fps and only decode)
3)Some other resources still shows 30fps but also for encoding.
So who is right? Why there are so many versions? Can Raspberry Pi 3 Model B (not B+)'s GPU encode and decode H.264 at 1080p 60 fps?

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Mon Jul 02, 2018 1:33 pm

Please note that those are all third party sites, so there is no way to influence them. People like to write about stuff, and they aren't always accurate.

The official spec sheet is at https://static.raspberrypi.org/files/pr ... -Brief.pdf
H.264, MPEG-4 decode (1080p30); H.264 encode (1080p30); OpenGL ES 1.1, 2.0 graphics
The chip was originally designed for 1080P30 encode and decode with VideoCore running at 250MHz. In reality the Pi is almost universally able to overclock the VideoCore blocks to 400MHz, to the extent that that is done automatically on "complex" H264 streams.
Decode is dependent on the exact bitstream. It will manage almost all 1080P60 streams, but it does depend on the bitrates involved. You have no come back should you find a stream that it can't play that exceeds 1080P30.

Encode again is a touch fluid. As above the guaranteed spec is 1080P30 (we always tested to 1080P33). I've got some tweaks which I hope make at least 1080P50 achievable, with the hope that 1080P60 may work too (the bottle-neck isn't always the codec blocks but keeping the pipeline flowing).
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

zervanko
Posts: 14
Joined: Sat Jun 23, 2018 6:36 pm

Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Mon Jul 02, 2018 2:37 pm

6by9 wrote:
Mon Jul 02, 2018 1:33 pm
Please note that those are all third party sites, so there is no way to influence them. People like to write about stuff, and they aren't always accurate.

The official spec sheet is at https://static.raspberrypi.org/files/pr ... -Brief.pdf
H.264, MPEG-4 decode (1080p30); H.264 encode (1080p30); OpenGL ES 1.1, 2.0 graphics
The chip was originally designed for 1080P30 encode and decode with VideoCore running at 250MHz. In reality the Pi is almost universally able to overclock the VideoCore blocks to 400MHz, to the extent that that is done automatically on "complex" H264 streams.
Decode is dependent on the exact bitstream. It will manage almost all 1080P60 streams, but it does depend on the bitrates involved. You have no come back should you find a stream that it can't play that exceeds 1080P30.

Encode again is a touch fluid. As above the guaranteed spec is 1080P30 (we always tested to 1080P33). I've got some tweaks which I hope make at least 1080P50 achievable, with the hope that 1080P60 may work too (the bottle-neck isn't always the codec blocks but keeping the pipeline flowing).
Thanks. Only one thing: you have provided link to Raspberry Pi 3 Model B+ (later 3B+) board, but I am talking about Model B (not plus, later 3B). Am I right, that GPU in 3B is similar to 3B+ and other Pis, but overclocked? If it is true, why here https://docs-emea.rs-online.com/webdocs ... 4ba5fd.pdf I do not see MPEG-4 decode for 3B, but in specs for 3B+ I can decode MPEG-4? or it is unofficial brief for 3B

6by9
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Raspberry Pi Engineer & Forum Moderator
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Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Mon Jul 02, 2018 3:18 pm

The VideoCore blocks inside the different versions of Pi are all identical. Only the ARM cores change.

H263, MPEG4, and H264 decode is supported on all Pis. MPEG2 and VC-1 decode are supported on all Pis if you buy the licence for them.
H264 encode is supported on all Pis.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

zervanko
Posts: 14
Joined: Sat Jun 23, 2018 6:36 pm

Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Wed Jul 04, 2018 6:52 am

6by9 wrote:
Mon Jul 02, 2018 3:18 pm
The VideoCore blocks inside the different versions of Pi are all identical. Only the ARM cores change.

H263, MPEG4, and H264 decode is supported on all Pis. MPEG2 and VC-1 decode are supported on all Pis if you buy the licence for them.
H264 encode is supported on all Pis.
You guys, don't think, that questions like that could be solved, if Raspberry Foundation will make normal documentation?
For example, https://www.raspberrypi.org/documentati ... -config.md at the end: This article uses content from the eLinux wiki page RPi raspi-config, which is shared under the Creative Commons Attribution-ShareAlike 3.0 Unported license
Something here https://www.raspberrypi.org/documentati ... /README.md

tetroider
Posts: 7
Joined: Fri Mar 02, 2018 7:05 pm

Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Wed Jul 04, 2018 3:04 pm

zervanko wrote:
Wed Jul 04, 2018 6:52 am
6by9 wrote:
Mon Jul 02, 2018 3:18 pm
The VideoCore blocks inside the different versions of Pi are all identical. Only the ARM cores change.

H263, MPEG4, and H264 decode is supported on all Pis. MPEG2 and VC-1 decode are supported on all Pis if you buy the licence for them.
H264 encode is supported on all Pis.
You guys, don't think, that questions like that could be solved, if Raspberry Foundation will make normal documentation?
For example, https://www.raspberrypi.org/documentati ... -config.md at the end: This article uses content from the eLinux wiki page RPi raspi-config, which is shared under the Creative Commons Attribution-ShareAlike 3.0 Unported license
Something here https://www.raspberrypi.org/documentati ... /README.md
Yea, 6by9, why official documentation fowards us to 3-rd party site for more info?

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 10312
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Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Wed Jul 04, 2018 3:35 pm

tetroider wrote:
Wed Jul 04, 2018 3:04 pm
Yea, 6by9, why official documentation fowards us to 3-rd party site for more info?
??! It doesn't.
3rd party content has been reused (as permitted by the licence), checked for errors, and republished on raspberrypi.org. A link has been provided back to the original source as a required by the licence of that source. What's your issue with that?

Documentation can always be improved, but it requires time and resource to do so. Which do you prefer, us to be working on keeping the software working and developing, or forgetting all about that and writing documentation instead?
The normal approach we take is that if someone asks a sensible question on the forum then the docs get updated to incorporate that and hopefully avoid the question being asked again. Reality is that very few people bother reading the docs that do get written, so the motivation for updating them is somewhat reduced.

The fact that the VideoCore blocks are identical in all Pi variants is in the documentation. https://www.raspberrypi.org/documentati ... /README.md
The underlying architecture in BCM2836 is identical to BCM2835. The only significant difference is the removal of the ARM1176JZF-S processor and replacement with a quad-core Cortex-A7 cluster.
https://www.raspberrypi.org/documentati ... /README.md
The underlying architecture of the BCM2837 is identical to the BCM2836. The only significant difference is the replacement of the ARMv7 quad core cluster with a quad-core ARM Cortex A53 (ARMv8) cluster.
(And why the attitude?)
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

ejolson
Posts: 6376
Joined: Tue Mar 18, 2014 11:47 am

Re: What is the true specifications of Raspberry Pi 3 Model B's GPU?

Mon Jul 09, 2018 5:26 am

6by9 wrote:
Wed Jul 04, 2018 3:35 pm
Reality is that very few people bother reading the docs that do get written, so the motivation for updating them is somewhat reduced.
Few students bother to read their textbooks; however, this doesn't make reading them less important. Since the online documentation for Raspberry Pi functions in a way similar to a textbook, putting extra care into writing good documentation appears important for the educational mission of the Raspberry Pi.

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