Big Sur Streaming Dropped frames on Custom Server


New Member
Hello, I have a particular problem and have been through all of the usual recommendations on troubleshooting dropped frames and connectivity issues. I am going to outline my setup and then describe the problem.

Streaming System 1 [Disconnecting]:
6-core 2018 Mac Mini
MacOS Big Sur
Streaming through OBS 27.0.0-rc6 (have tried all previous releases, each a clean install)
Streaming target: local ip: xx.xx.xx.13
Issue: 80% dropped frames, rapid and frequent disconnects (was working before upgrade to Big Sur)
NIC: 10gbe

Streaming System 2 [Working]:
6-core 2018 Mac Mini
MacOS Catalina
Streaming through OBS 26.1.2
Streaming Target: local ip: xx.xx.xx.13
Issue: No issue, video streams perfectly.
NIC: 10gbe

Self-Hosted Streaming Server:
Small 6-core Linux box
CentOS 7
Running Ant Media server @ local ip xx.xx.xx.13
Running Apache Webserver to a public domain
NIC: 10gbe

Streaming System 1 cannot successfully stream to my custom streaming server. All other networking on Streaming System 1 is fully functional (full 10gbe tested with NAS and SAN access). It CAN successfully stream to youtube twitch, etc. It is just the local Self-Hosted Streaming server @ xx.xx.xx.13 that OBS has connectivity issues with. Additionally, System 1 was fully functional prior to the Big Sur upgrade, when this issue arose. According to the LOGs, the errors I am receiving are thus:

11:01:41.836: [x264 encoder: 'streaming_h264'] preset: veryfast
11:01:41.836: [x264 encoder: 'streaming_h264'] profile: high
11:01:41.836: [x264 encoder: 'streaming_h264'] tune: zerolatency
11:01:41.836: [x264 encoder: 'streaming_h264'] settings:
11:01:41.836:     rate_control: CBR
11:01:41.836:     bitrate:      6000
11:01:41.836:     buffer size:  6000
11:01:41.836:     crf:          23
11:01:41.836:     fps_num:      24000
11:01:41.836:     fps_den:      1001
11:01:41.836:     width:        1920
11:01:41.836:     height:       1080
11:01:41.836:     keyint:       23
11:01:41.851: [CoreAudio AAC: 'adv_stream_aac']: settings:
11:01:41.851:     mode:          AAC
11:01:41.851:     bitrate:       160
11:01:41.851:     sample rate:   48000
11:01:41.851:     cbr:           on
11:01:41.851:     output buffer: 1536
11:01:41.851: [rtmp stream: 'adv_stream'] Connecting to RTMP URL rtmp://
11:01:41.851: [rtmp stream: 'adv_stream'] Binding to IPv4
11:01:42.782: [rtmp stream: 'adv_stream'] Connection to rtmp:// successful
11:01:42.785: ==== Streaming Start ===============================================
11:02:04.312: WriteN, RTMP send error 32 (4097 bytes)
11:02:04.313: WriteN, RTMP send error 32 (59 bytes)
11:02:04.313: WriteN, RTMP send error 9 (42 bytes)
11:02:04.313: [rtmp stream: 'adv_stream'] Disconnected from rtmp://
11:02:04.313: Output 'adv_stream': stopping
11:02:04.313: Output 'adv_stream': Total frames output: 105 (513 attempted)
11:02:04.313: Output 'adv_stream': Total drawn frames: 538
11:02:04.313: Output 'adv_stream': Number of dropped frames due to insufficient bandwidth/connection stalls: 408 (79.5%)
11:02:04.313: [rtmp stream: 'adv_stream'] Freeing 1065 remaining packets
11:02:04.319: ==== Streaming Stop ================================================
Streaming System 2 works perfectly and is the exact same model and build as System 1. Therefore, I know that it is not a networking issue with the router or my ISP. Furthermore, it is not an issue with my Self-Hosted Streaming Server either, as System 2 works perfectly with it.

System 1 cannot be downgraded to Catalina, due to production requirements, so I am looking for a solution or verified bug to report to the devs on OBS.


New Member
I feel like we have a similar issue. I’m not the most technical but here we go.

Old iMac 1:

Streamed for 4 months with occasional issues but not related to missing frames


New iMac 2:

Trying to setup for streaming but dropping frames at all settings (1080/60 -720/30)


For 4 months I streamed with Mac1 on Twitch with a consistent 720p 30fps in OBS. Everything was running fine up until last Friday when I attempted to setup Mac2 in OBS.

Mac1 ran on several versions of OBS but most recently with OBS version 27.0.1 on Catalina. I was running 720p 30fps with minimal hiccups (alerts not working, mic shutting off mid stream, being live on twitch but no signs of being live in OBS via Twitch stats, among other things). For the most part Mac1 did well but it was past it’s time and I was ready to upgrade.

I decided to purchase the iMac2 (iMac 2020) and sadly with this machine spec’d out I can’t achieve the same quality stream as my Late 2015 quad i7! I’m running big sur and can’t change it to Catalina(old Mac). The new iMac 2020 was “missing frames due to rendering lag”. I have a lot of heavy scenes in OBS and noticed 20-25 frames lost. The lowest at any time I could get was 4 missing frames. I followed twitch’s guidelines for streams ranging from:


The missed/dropped frames continued through attempting the recommended settings with varying results.

I reconstructed some of my sources (normally text and brand images) in illustrator and found I was able to eliminate some of the missing frames but still find I’m dropping 2-4 frames here and there. (Normally in scenes loaded with sources-combination of video overlays, images, music, text, alerts etc).
Once I am able to eliminate the missing frames some more I plan to retest the recommended settings for twitch however I’m very pessimistic towards positive results. Honestly I’m also baffled my Late 2015 model handles OBS better. How is this possible? Is it a Big Sur/OBS issue? So far this has my head ready to pop off. Oh I didn’t mention I also setup boot camp and updated the gpu driver but it did t change anything.

Thanks for any help, hope this can help you or someone else in some way.