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Observer
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Registered: ‎09-22-2018

## Maximum number of simultaneous decode&encode 720 stream?

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
1,159 Views
Registered: ‎08-01-2007

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

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
Versal ACAP: AI Engines | Embedded SW Support

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Xilinx Employee
1,160 Views
Registered: ‎08-01-2007

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

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
Versal ACAP: AI Engines | Embedded SW Support

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Observer
1,139 Views
Registered: ‎09-22-2018

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

Dear chrisar,

• 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
1,109 Views
Registered: ‎11-09-2015

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

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
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Moderator
1,032 Views
Registered: ‎11-09-2015

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

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)

Thanks and Regards,

Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Observer
985 Views
Registered: ‎09-22-2018

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

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?

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Moderator
914 Views
Registered: ‎11-09-2015