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#1 Posted : Tuesday, September 27, 2022 4:20:09 AM(UTC)

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I am interested in the real number of encoding streams being created by vMix through the GPU. We have always used A6000 cards for our system builds, mostly because they were so expensive they were always available somewhere during the Bitcoin/Ethereum mining wars but they also happen to have no restriction on the number of encoding streams. Now that the wars are over I have been considering switching to a GeForce RTX 3080 Ti Gaming OC 12GB or similar. In some ways the specs on those cards can actually be higher in Cuda cores and processing speed than the A6000s but there is the 3 encoder limit to consider.

Our typical set up includes 4-6 NDI cameras and occasionally 1 or 2 SDI cameras through a Decklink Duo 8 capture card. We typically stream to just 1 source or use Restream to stream to multiple sources. We often record the show with the vMix Record feature, with Output 1 being the primary source for Recording/Streaming and the External to the talent monitor. Fullscreen 1 is a multiview, Fullscreen 2 is Output and I have 3 monitors powered by the A6000, 2 of which are Display port connections to the vMix operator monitors for the higher resolution and 1 is HDMI for the producer multiview. Output 1 is output with NDI on and Output 2 is a specific camera input with NDI on, also used by the producer. Under Additional NDI outputs Camera/calls/audio inputs are on are are the Audio inputs.

So my question is how many encoders are actually in play here?

Next to Output 1 on the main settings screen it lists Record/Stream/External. In my case, External is used to fill the talent monitor from the Decklink Due through an SDI connection to a Blackmagic SDI to HDMI converter using the External Renderer. So I don't think that is a stream but is the Stream and Record NDI output 1 encoder in use or 2 instances?

Record is clearly using a encoder if MP4 is being used and I don't want to switch to AVI, FFMPEG or vMixAVI(What is that?) which would not need an encoder as Use Hardware Encoder disappears when you select them.

Stream is using an encoder but is it its own instance or the same stream that Record is using from Output 1? Output 2 would seem to be using an encoder as well and I have no idea if the additional NDI outputs require an encoder.

So best case scenario Record & Stream use 1 encoder, Output 2 uses 1 encoder, External does not use an encoder nor does the other Additional NDI Outputs for a total of 2 encoders in use.

Worst case scenario Record uses an encoder, Stream uses an encoder, Output 1 and 2 each uses an encoder and the additional NDI Outputs could be using 1-2 encoders for a total of 4 - 6 encoders.

FYI there is no SRT or RTMP as part of our productions. So how many encoders are really being used as that 3 encoder maximum could have real impact depending on how some of these outputs are handled by vMix?
#2 Posted : Tuesday, September 27, 2022 10:00:21 PM(UTC)

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@ DMack

To the best of my knowledge, NDI does not/will not use the NVIDIA NVENC encoder, the "Use Hardware Encoder" option in vMix only enables h.264 encoding for streaming and/or recording.
As such, each stream destination and/or recording requires its own encode and so with a GeForce card, any combination of those that totals to 3 is where you reach the limit.
So, if you only have one stream destination and one recording, that would be two NVENC encodes only.

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