V4L2 USB Camera Stream Stutters When Another NDI Source is on the Same LAN

[saltarob]

Issue Description:

I am running Dicaffeine on a Raspberry Pi 5 connected to a 1 Gbps LAN via Ethernet. The Pi is capturing a 1080p50 signal from a Sony A7S camera connected through a CamLink 4K on the USB3 port. The NDI signal is being received on a MacBook Pro or Mac Pro, both connected to the same gigabit switch as the Pi.

Problem:

When the Pi 5 with Dicaffeine is the only NDI source on the LAN, the NDI stream is flawless, with an average bitrate of 125 Mbps. However, when I connect my Mevo NDI camera, which streams at 15 Mbps (NDI HX), the Dicaffeine stream starts to stutter. This issue occurs regardless of the application used to receive the stream (OBS, Wirecast, or NDI Monitor).

Observations:

1. Network Congestion: Initially, I suspected network congestion. However, the network handles approximately 150 Mbps, which shouldn’t be an issue on a 1 Gbps LAN. Testing with the Sony camera connected to the MacBook Pro and streaming via OBS over the same network showed no issues, even with multiple streams totaling around 400 Mbps.

2. NDI Stream Analysis: Using NDI Analysis, I observed that when Dicaffeine is the only NDI source, the stream is stable. However, when the Mevo NDI source is added, the Dicaffeine stream disconnects and reconnects frequently, with significant frame delays. Unfortunately, I can only analyze the stream on the receiver side since NDI Analysis is only available on Windows.

Request for Assistance:

I’m puzzled by how the presence of another NDI source (Mevo) on the LAN can cause such significant issues with the Dicaffeine NDI stream. I’m looking for ideas on how to troubleshoot or narrow down the cause of this problem.

Thank you for your help!