r/MidiNet • u/micro2970 • 10d ago
Midinet v0.1 for Digital Audio
Midinet protocol for delivering Digital Audio with Midi timestamps in common Ethernet.
What ?
Midinet delivers digital audio with Midi timestamps in Ethernet with very low latencies directly between synthesizers without routers and hubs. Midinet digital audio packets include Midi JR timestamps for exact syncing between Midi note events and digital audio. The user can select both daisy chain and star topology with Ethernet cables.
In daisy-chain, you can connect tens of synthesizers with under 5 millisecond round-trip latency for Midi packets and digital audio. Midinet protocol is designed mainly for home synth setups. You can also listen to all synths from one synths output jack, without any analog mixers or cables. You can also calculate songs faster than real time (burst-mode with Midi timestamps). Synthesizers send complete tracks, like bass-lines, back to the computer in a few seconds. Synthesizers can create their own audio stream or mix their audio to existing stream.
Protocol latency test below with ethernet cables and packet forwarding.
Why ?
Altough there are similar protocols like Dante, Aes67, A2B, IEEE etc. those often require specialized hardware and lack features like faster-than-realtime audio, on-the-go mixing and Midi timestamps. Many also require an expensive license, while Midinet is free and open. Midinet protocol is designed mainly as a light-weight digital audio alternative for home synthesizers.
json at synthesizers
midinet-stream-id 0 ; stream id
midinet-stream-enable 10 ; enabled seconds
midinet-stream-type create ; create or mix to stream (daisy-chain)
midinet-stream-time realtime ; realtime (udp) or burst (tcp)
midinet-stream-server-ip 192.168.1.51
midinet-stream-server-protocol udp
midinet-stream-server-port 7002
midinet-stream-format-hz 48000
midinet-stream-format-bps 32
midinet-stream-format-floating-point 0
midinet-stream-format-channels 2
midinet-stream-format-samples 24
midinet-stream-format-byte-order 0
midinet-stream-format-divider 1
midinet-stream-format-header-type 0
midinet-stream-format-db0 24
midinet-stream-include-midich all
midinet-stream-include-note all
midinet-stream-include-instrument all
midinet-stream-include-velocity all
midinet-stream-include-pitchbend all
midinet-stream-control-volume 65535
midinet-stream-control-pan 32768
midinet-stream-control-effect-type 0
midinet-stream-control-effect-value 0
midinet-stream-status ok ; ok,error,busy
Ethernet packet format for audio
StreamID, Flags, Midi JR timestamp of the first sample (extrapolated), Packetcount, AudioData.
flags: JR valid(0), packetcount valid(1), JR reset(2), packetcount reset(3), JR rounded(4)
Byte 0 Byte 1 Byte 2 Byte 3
┌────────────────┬────────────────┬────────────────────────────────┐
│ StreamID (8b) │ Flags (8b) │ Midi JR (16b) │ <- First 32 bits
├────────────────┴────────────────┴────────────────────────────────┤
│ PacketCount (32b) │ <- Second 32 bits
├──────────────────────────────────────────────────────────────────┤
│ │
│ AudioData (PCM) │ <- Audiodata starts here
│ │
Audio server
- Modifies json parameters at synthesizers (Midi 2.0 PE, Http put/patch, ..)
- Receives the sent digital audio packets.
Server runs on computers or synthesizers, so you could listen to all synths from single synths output port.
Protocol and latency test
Protocol and latency test used two 3Ghz x86-64 computers with i8256x network cards.
- Computer A sent audio waveform packet with rdtsc-timestamp to Computer B
- Computer B summed its own waveform to the audio packet and sent it back to Computer A
- Computer A displayed the difference in rdtsc timestamp / 2 to get the per hop latency.
At 100mbps, latencies for Ethernet UDP packet with store/forward are following:
- Midi note packet (16 bytes) - below 40 microseconds
- Audio packet (8 byte header + 24 samples * 2 channels * 32bits) - below 60 microseconds
100Mbps - 50 synths in daisy-chain has a round-trip latency under 5 milliseconds.
1000Mbps - 70 synths in daisy-chain has a round-trip latency under 5 milliseconds.
Comparison to other audio protocols
=====================================================================================================
Feature Midinet IEEE avb/tsn Aes67/Ravenna A2B Dante
=====================================================================================================
Licensing Free/Open Free/Open Free/Open Prop.chips Proprietary
Hardware Standard Req.AVB/TSN Standard A2B transc. Dante HW or
Ethernet switches Ethernet No ethernet Ethernet+Hub
Control Midi 2.0 PE, IEEE-802/1722 mDNS,RTSP,NMOS Proprietary Dante
Http (json) software Controller
Streamtypes Individual Individual Individual Individual Individual
Mixed
Streamtime Realtime Realtime Realtime Realtime Realtime
Burst
Timing Midi JR PTPv2 PTPv2 Time-Division PTPv1/PTPv2
Multiplex
=====================================================================================================
Links
2
u/Specialist-Dog-501 2d ago
I don't understand all of it, but impressed! Hope you find some devs supporting this, awesome!