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Visitor elahi
Visitor
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Registered: ‎09-22-2018

Maximum number of simultaneous decode&encode 720 stream?

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Hello, 
I wonder how many 720p stream can I decode&encode simultaneously with VCU. In the VCU ipcore configuration, when I change the number of streams from 1 to 8, I see no change in Decoder Bandwidth requirements. 

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-01-2007

Re: Maximum number of simultaneous decode&encode 720 stream?

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The Zynq UltraScale+ MPSoC VCU actually consists of 2 parts, the Encoder and Decoder. Each part (Encoder and Decoder) has a maximum throughput. This throughput is equal to 1 stream of 4Kp60 video.  The same bandwidth can be split up in to smaller streams.

  • In 2018.2 and earlier the max number of supported streams was 8
  • In 2018.3 and later the max number of supported streams was increased to 32

So you can split up the bandwidth across multiple streams.  In the case of 720p60 you will find that 8 streams of 720p60 is equivalent to 1 stream of 4Kp60, so that it why you probably do not see very little to no change in the bandwidth requirements.  NOTE:  These are estimates because you have to account for stream complexity and frame size.  The GUI will always assume the worst case.  In addition, because the Zynq UltraScale+ MPSoC VCU can be changed on the fly from 8 streams to 1 stream, it also assumes that you might switch between the 2 modes.

Here are some quick estimates for 720p60 and 4Kp60 raw bandwidth (NOTE: These calculations to do not take into account pixel bit-widths, which can be 8 or 10-bit per component.):

  • (1280x720 * 60) * 8 streams = (921,600 * 60) * 8 = (55,296,000) * 8 = 442,368,000
  • (3840x2160 * 60) * 1 stream = (8,294,400 * 60) * 1 = (497,664,000) * 1 = 497,664,000
Chris
Video Design Hub | Embedded SW Support

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Xilinx Employee
Xilinx Employee
409 Views
Registered: ‎08-01-2007

Re: Maximum number of simultaneous decode&encode 720 stream?

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The Zynq UltraScale+ MPSoC VCU actually consists of 2 parts, the Encoder and Decoder. Each part (Encoder and Decoder) has a maximum throughput. This throughput is equal to 1 stream of 4Kp60 video.  The same bandwidth can be split up in to smaller streams.

  • In 2018.2 and earlier the max number of supported streams was 8
  • In 2018.3 and later the max number of supported streams was increased to 32

So you can split up the bandwidth across multiple streams.  In the case of 720p60 you will find that 8 streams of 720p60 is equivalent to 1 stream of 4Kp60, so that it why you probably do not see very little to no change in the bandwidth requirements.  NOTE:  These are estimates because you have to account for stream complexity and frame size.  The GUI will always assume the worst case.  In addition, because the Zynq UltraScale+ MPSoC VCU can be changed on the fly from 8 streams to 1 stream, it also assumes that you might switch between the 2 modes.

Here are some quick estimates for 720p60 and 4Kp60 raw bandwidth (NOTE: These calculations to do not take into account pixel bit-widths, which can be 8 or 10-bit per component.):

  • (1280x720 * 60) * 8 streams = (921,600 * 60) * 8 = (55,296,000) * 8 = 442,368,000
  • (3840x2160 * 60) * 1 stream = (8,294,400 * 60) * 1 = (497,664,000) * 1 = 497,664,000
Chris
Video Design Hub | Embedded SW Support

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Visitor elahi
Visitor
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Registered: ‎09-22-2018

Re: Maximum number of simultaneous decode&encode 720 stream?

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Dear chrisar, 

thanks for your reply. But what do you mean by 

  • In 2018.2 and earlier the max number of supported streams was 8
  • In 2018.3 and later the max number of supported streams was increased to 32

is it vivado version? How vivado version can impact the maximum throughput of VCU?

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Moderator
Moderator
358 Views
Registered: ‎11-09-2015

Re: Maximum number of simultaneous decode&encode 720 stream?

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Hi @elahi,

The change is not really done in Vivado but in the firmware/driver layer. 2018.2/2018.3 is the name of the release for Vivado/SDK/drivers etc...

Note that the throughput is not impacted. The maximum throughput you can get is a total bandwidth of 4k@60. Only the number of streams supported is changed.

Hope that clarifies,

Best Regards


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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Moderator
Moderator
281 Views
Registered: ‎11-09-2015

Re: Maximum number of simultaneous decode&encode 720 stream?

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Hi @elahi,

Is everything clear for you on this subject?

If your question is answered or your issue is solved, please kindly mark the response which helped as solution (click on "Accept as solution" button below the reply)

If this is not solved/answered, please reply in the topic giving more information on your current status.

Thanks and Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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Visitor elahi
Visitor
234 Views
Registered: ‎09-22-2018

Re: Maximum number of simultaneous decode&encode 720 stream?

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I've just installed Vivado 2018.3. But the maximum supported stream for is still 8. Also the lowest possible resolution is still HD. Why is that? 

vcu8Stream.png

 

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Moderator
Moderator
163 Views
Registered: ‎11-09-2015

Re: Maximum number of simultaneous decode&encode 720 stream?

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Hi @elahi,

The GUI is not correctly reporting this new configuration. This was already reported to the development team.

You use the option to get the maximum aggregated bandwidth you need. Then you configure to 32 streams in the SW layer.

Best Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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