Hi Keith

I asked pretty much the same question lately. No answer so far

See : https://forums.vmix.com/...ts&m=53480#post53480

Guillaume

Hi

Whilst not entirely convenient, I am using an external ffmpeg command line to pick up the VMIX Directshow output, and then using carefully hand crafted ffmpeg command lines to encode the VMIX output into 8 x h.264 streams each with differing resolutions and bit rates on a £50 second hand ebay NVIDIA QUADRO K2000 (Gforce GTX cards are restricted to a maximum of 2 streams). As I only need 4:2:0 h.264 it seemed pointless using a modern expensive GPU. ffmpeg also allows you to select which GPU card you want to use, so hopefully I can get a GTX-1060 to register as GPU0 and let VMIX take control of that, and use a second K2000 as GPU1 to do all my encoding.

BTW the hardware acceleration implementation built-in to flash media encoder sucks - it barely uses the GPU, and the h.264 encoder available in flash based apps is even worse. I don't honestly think it actualy uses the GPU's for anything. The FMLE multi-bitrate streaming system sucks - use a CDN that can transcode for you, or buy a Quadro card, and let ffmpeg take the strain.

If anybody is interested in my command line - Using current (May 2018) FFMPEG Windows Stable Build, this is for 4 streams, at the highest possible performance, at the sacrifice of latency and quality. You can easily expand it to support as many streams as your 'QUADRO' graphics card can handle at a given performance, I can max out about 9/10 high performance streams on a K2000, I would imagine you can do 30 or 40 on a new P6000 card (just don't have the spare $5000 to try it out).




Probably still needs some tweaking (some of the profile/levels are a bit high for the lower resolutions)- but please remember you can ONLY do two streams in hardware on consumer Gforce GTX cards, so this will error when it try's to start the third and fourth stream. But with the right GPU card (remember mine was only £50 on Ebay) you can turn your VMIX into a streaming power house.

Of the 2Gb of RAM on the K2000 Quadro we are running at about 200kbyts - plenty of spare RAm if you want to use the CUDA cores for something (h.264 encoding does NOT use the CUDA cores - there are separate pipelined h.264 encoders on NVIDI GPU's - they just share the RAM, and it appears that h.264 encoding dosen't use much of it. So dont be tempted by cards with 12Gb of DDR5, you wont use any of it if your using your card for encoding.

Hey Martin, how about offering us Quadro Users the ability to do say 8 web streams? but we would need a little more control in setting presets as some may want slow 2 pass ultra high quality, and some people like me is more about the number of simultaneous CDN's and bitrates I need to connect to.

There are plenty of philosophers out there that will argue the subjective quality issues between the cpu based x.264 encoder and hardware NVENC encoding - personally even at high performance NVENC produces a perfectly acceptable result for the kind of streaming we are all doing (that presuming your not the BBC).

All The Best

Keith

Oh btw I came here to copy Martin's answer about this from another post.



Thanks Martin