[FFmpeg-user] Need help with Live Streaming using GPU

Karan Singh karanveersingh5623 at gmail.com
Thu Oct 10 04:11:11 EEST 2019

Hi Team

Any update on this?

i am struggling with live streaming of 4k videos with or without GPU.

My question before describing my issue is what is number of 4k videos that
can transcoded and live streamed using below configuration .

1 X R740xd dell system  - configuration is 2 socket , 88 core processors
with 256 GB of RAM- (ubuntu 18.04.02 OS )


Tesla T4 GPU


Nginix & RTMP

Transcoding and streaming all happening in one system , viewing of stream
is in windows system with vlc player .

Below is the first command I was trying , the issue is that the video live
streaming runs perfectly with 6 simultaneous streams of 4k but when the 7th
stream starts , all goes bad and fps start dropping [ Its with CPU ] . The
only thing i notice is more CPU utilization and that could be reason of FPS

ffmpeg -re -i Stranger09.mkv -c:v libx264 -b:v 50M -preset ultrafast -tune
zerolatency -b:a 128k -s 4096x2160 -bufsize 5M -x264opts keyint=500 -g 60
-pix_fmt yuv420p -f flv rtmp://

Some guys on IRC channel recommended me to omit / edit below mentioned
parameters but still its not working

Remove -tune zerolatency

keyint=500 -g 60 , both are same so does use it together

need to limit thread by adding  -thread x

I tried using GPU to scale up the simultaneous streaming but it also going
bad after 6 streams , below is the command . Here I can see less CPU
utilization , like 20% , 80% is still free but GPU is 100% stressed .

fmpeg -hwaccel_device 1 -hwaccel cuvid -re -i Stranger02.mkv -c:v
h264_nvenc -preset fast -b:v 10M -bufsize 20M -x264opts keyint=500 -pix_fmt
yuv420p -f flv rtmp://

I tried using GPU + CPU as 80% CPU is free after 100% GPU utilization but I
cannot run more than 7 simultaneous streams .

Please help me with correct usage of FFMPEG to scale up the 4k videos .

My end goal is to achieve 1Gbps read/writes on storage media. Network is
not in picture as transcoding and streaming all running on 1 server .

On Wed, Oct 9, 2019 at 10:47 AM Karan Singh <karanveersingh5623 at gmail.com>

> >  The nginx server, how many workers are running?
> 1024 workers running
> On Tue, Oct 8, 2019 at 12:14 PM Ted Park <kumowoon1025 at gmail.com> wrote:
>> > Is there any other issue that is causing problems in running more
>> number of
>> > simoultaneus streams ?
>> The nginx server, how many workers are running?
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