threefive 3.0.81

threefive is The #1 SCTE-35 Decoder and Encoder on the Planet.

It is now official, phase three of threefive's global domination has begun. Behold threefive.js

(ominous music plays in the background)

[ threefive ]

... If someone says they don't use threefive for SCTE-35, they're either drunk or they're lying.
~Adrian

https://github.com/superkabuki/threefive

threefive is the industry leading SCTE-35 tool.

Need to inject SCTE-35 into HLS? X9k3.

• Decodes SCTE-35 from MPEGTS✔ Base64✔ Bytes✔ DASH✔ Hex ✔ HLS✔ Integers✔ JSON✔ XML✔ XML+Binary✔

• Encodes SCTE-35 to MPEGTS✔ Base64✔ Bytes✔ Hex✔ Integers✔ JSON✔ XML✔ XML+Binary✔

• Injects SCTE-35 Packets into MPEGTS✔.

• Network support for HTTP(s)✔ Multicast✔ UDP✔ SRT✔

• Built-in Multicast Server✔

• Automatic AES decryption✔

---

[ News ]

• threefive no longer uses setuptools for packaging and I know you don't care.
• Python3 vs. Pypy3 parsing SCTE35 with threefive (watch the cool video)
• threefive now supports Secure Reliable Transport (watch the cool video)
• I have been trying to setup threefive on readthedocs,it's not going very well, but I'm working on it.

---

[ Latest version is v3.0.81 ]

• threefive cyclomatic complexity score is 1.9337094499294782 ( that's better than the Python standard library) .
• threefive now has NO External Dependencies
  • SRT and AES support is now optional
• threefive is fully python v3.14 compliant
  • I fixed everything they broke/changed between v3.09 and 3.14.
  • 0 deprecation warnings.
• No more setup tools! threefive now uses a toml file and a Makefile to generate packages,
  • I'm just trying to fit in with the cool python kids.
• fix for addressable tv Upids
• fix for private descriptor encoding and xml encoding.
• New the threefive cli tool has spun off several new cli tools. I had to split the cli up, the help was just way too long.
  • In addition to the threefive cli you also get:
    • scte35bump adjust scte-35 pts in mpegts streams
    • scte35fix change bin data streams back to scte-35
    • scte35hls parse scte-35 from hls tags and segments
    • scte35inject inject scte-35 packets into mpegts streams
    • gums (the Grande Unified unicast and Multicast Server)

[Examples]

[ Documentation ]

• use threefive on the web

  • threefive SCTE-35 Online Parser hosted on my server_
  • SCTE-35 Online Parser powered by threefive another online parser powered by threefive
  • SCTE-35 As a Service if you can make an http request, you can parse SCTE-35, no install needed.

• install

• command line tools

  • threefive decode SCTE-35 on the command line
  • scte35bump adjust SCTE-35 PTS in MPEGTS streams
  • scte35fix ffmpeg changes scte-35 streams into bin data, scte35fix changes them back.
  • scte35hls scte35hls parses hls and ABR hls for scte-35. All hls scte-35 tags are supported_
  • scte35inject scte35inject inject scte-35 into mpegts.
  • gums gums is a multicast sender(server) for video

• library

  • Using the threefive.Cue class
  • Using the threefive library decode SCTE-35 with less than ten lines of code
  • • threefive Classes threefive is OO, made to subclass
      • Cue Class this class you'll use often
      • Stream Class this is the class for parsing MPEGTS

• Use threefive to stream Multicast threefive is a multicast client and server

• SCTE-35 Sidecar Files threefive supports SCTE-35 sidecar files

• SuperKabuki SCTE-35 MPEGTS Packet Injection inject SCTE-35 into MPEGTS streams

• SCTE-35 HLS parse SCTE-35 in HLS_

• SCTE-35 XML and More XML threefive can parse and encode SCTE-35 xml

• Encode SCTE-35 threefive can encode SCTE-35 in every SCTE-35 format

• Make your threefive script an executable with cython threefive is compatible with all python tools

[Install]

• python3 via pip

python3 -mpip install threefive

• pypy3 via pip

pypy3 -mpip install threefive

• To add SRT support

python3 -m pip install srtfu

• To add Automatic AES decryption

python3 -mpip install pyaes

• From the git repo

git clone https://github.com/superkabuki/scte35.git
cd threefive
make install

• I've jazzed up the makefile to make it easier to install for different python versions and pypy3

git clone https://github.com/superkabuki/scte35.git
cd threefive

make install py3=pypy3

# OR

make install py3=python3.14

# works for any python in your path or use a full path if needed.

---

[Quick Start]

[CLI]

• The default action is to read a SCTE-35 input and write a SCTE-35 output.

---

[ Parse SCTE-35 from MPEGTS ]

• SCTE-35 Input: MPEGTS
• Protocols: pipes, files, stdin, http(s), multicast,SRT and UDP.
• SCTE-35 Output: JSON (default) base64, bytes, hex, int, xml, and xmlbin.

SCTE-35 Input	Protocol	SCTE-35 Output	Command
MPEGTS	file	JSON	threefive video.ts
.	https	base64	threefive https://example.com/video.ts base64
.	multicast	bytes	threefive udp://@235.3.5:3535 bytes
.	SRT	hex	threefive srt://1.2.3.4:4201 hex
.	UDP	int	threefive udp://10.10.10.10:1011 int
.	Pipe	xml	cat video.ts | threefive xml
.	stdin	xml+bin	threefive xmlbin < video.ts

---

[ Parse SCTE-35 Cues ]

• The default output is JSON
• SCTE-35 Inputs: base64, hex, int, JSON,int,xml,and xmlbin.
• SCTE-35 Outputs: base64, bytes, hex, int,JSON, xml, and xmlbin.
• Any Input can be used with Any Output

Here are several examples.

SCTE-35 Input	SCTE-35 Output	Command
base64	JSON	threefive '/DAWAAAAAAAAAP/wBQb+AKmKxwAACzuu2Q=='
.	bytes	threefive '/DAWAAAAAAAAAP/wBQb+AKmKxwAACzuu2Q==' bytes
.	hex	threefive '/DAWAAAAAAAAAP/wBQb+AKmKxwAACzuu2Q==' hex
.	xml	threefive '/DAWAAAAAAAAAP/wBQb+AKmKxwAACzuu2Q==' xml
hex	JSON	threefive 0xfc301600000000000000fff00506fe00a98ac700000b3baed9
.	base64	threefive 0xfc301600000000000000fff00506fe00a98ac700000b3baed9 base64
.	int	threefive 0xfc301600000000000000fff00506fe00a98ac700000b3baed9 int
.	xmlbin	threefive 0xfc301600000000000000fff00506fe00a98ac700000b3baed9 xmlbin
int	JSON	threefive 1583008701074197245727019716796221242036302348025116111908569
.	hex	threefive 1583008701074197245727019716796221242036302348025116111908569 hex
.	xml	threefive 1583008701074197245727019716796221242036302348025116111908569 xml
JSON	base64	threefive < json.json base64
.	bytes	threefive < json.json bytes
.	xml	threefive < json.json xml
xml	JSON	threefive < xml.xml
xmlbin	int	threefive < xmlbin.xml int

---

[Additional functionality]

• threefive has several additional features, mostly related to MPEGTS streams.
• threefive has built in help, just type threefive help
• This table shows how to use them.

Description	How To Use
Inject SCTE35 packets	threefive inject -i in.video -s sidecar.txt -o out.ts
Show raw SCTE35 packets	threefive packets udp://@235.35.3.5:3535
Copy MPEGTS stream to stdout at realtime speed	threefive rt input.ts
Create SCTE35 sidecar file	threefive sidecar video.ts
Show streams in mpegts stream	threefive show https://example.com/video.ts
Show iframes in mpegts stream	threefive iframes srt://10.10.1.3:9000
Show PTS values from mpegts stream	threefive pts udp://192.168.1.10:9000
Proxy the mpegts stream to stdout	threefive proxy https://wexample.com/video.ts

---

Other tools

threefive also comes with:

scte35bump

• bump adjusts SCTE-35 PTS in an MPEGTS stream

$ scte35bump -h
usage: scte35bump [-h] [-i INFILE] [-o OUTFILE] [-s SECS]

options:
  -h, --help            show this help message and exit
  -i INFILE, --infile INFILE
                        Input source, stdin, file, http(s), udp, or multicast
                        mpegts [default: sys.stdin.buffer]
  -o OUTFILE, --outfile OUTFILE
                        Output file [default: sys.stdout.buffer]
  -s SECS, --secs SECS  Adjustment to apply to SCTE-35 Cues. [default: 0.0]

scte35bump is part of threefive.

---

gums

• the Grande Udp Multicast Server

$ gums -h
usage: gums [-h] [-i INPUT] [-a ADDR] [-b BIND_ADDR] [-t TTL]

options:
  -h, --help            show this help message and exit
  -i INPUT, --input INPUT
                        like "/home/a/vid.ts" or "https://futzu.com/xaa.ts"
                        [default: sys.stdin.buffer]
  -a ADDR, --addr ADDR  Destination IP:Port [default: 235.35.3.5:3535]
  -b BIND_ADDR, --bind_addr BIND_ADDR
                        Local IP to bind [default: 0.0.0.0]
  -t TTL, --ttl TTL     Multicast TTL (1 - 255) [default: 32]

gums is part of threefive.

scte35hls

• parse HLS for SCTE-35. Supports all HLS SCTE-35 tags.

$ scte35hls -h

[ threefive hls ]

[ Help ]

    To display this help:
	scte35hls help

[ Input ]
    threefive hls takes an m3u8 URI as input.
    M3U8 formats supported:
        * master  ( When a master.m3u8 used,
                   threefive hls parses the first rendition it finds )
        * rendition
    Segment types supported:
    * AAC
    * AC3
    * MPEGTS
    *codecs:
        * video
            * mpeg2, h.264, h.265
        * audio
            * mpeg2, aac, ac3, mp3

scte35fix

• when ffmpeg changes a SCTE-35 stream to bin data stream, scte35fix changes it back.

$ scte35fix -h

  scte35fix checks MPEGTS for SCTE-35 Streams
  that have been change to bin data (type 0x06)
  and changes them back to SCTE-35 (type 0x86) streams.
  Output files are created in the current directory
  and prefixed with 'sixfix-'.
  Only bin data streams containing SCTE-35 will be converted.
  Multiple files can be specified on the command line.
  Wild cards work too.

  Example Usage:
        scte35fix video.ts
        scte35fix video1.ts video2.ts
        scte35fix video*.ts
        scte35fix https://example.com/video.ts
        scte35fix srt://10.10.10.13:4201
scte35fix is part of threefive.

[XML]

• XML New! updated 05/01/2025

[HLS]

• Advanced Parsing of SCTE-35 in HLS with threefive All HLS SCTE-35 tags, Sidecar Files, AAC ID3 Header Timestamps, SCTE-35 filters... Who loves you baby?

[SCTE-35 As a Service]

• Decode SCTE-35 without installing anything. If you can make an https request, you can use Sassy to decode SCTE-35. .

[Classes]

• The python built in help is always the most up to date docs for the library.

a@fu:~/build7/threefive$ pypy3

>>>> from threefive import Stream
>>>> help(Stream)

• Class Structure
• Cue Class Cue is the main SCTE-35 class to use.
• Stream Class The Stream class handles MPEGTS SCTE-35 streams local, Http(s), UDP, and Multicast.

---

[threefive now supports SRT]

• ( You have to unmute the audio )

https://github.com/user-attachments/assets/a323ea90-867f-480f-a55f-e9339263e511

• more SRT and threefive info

• checkout SRTfu

---

[more]

• Online SCTE-35 Parser Supporte Base64, Bytes,Hex,Int, Json, Xml, and Xml+binary.

• Encode SCTE-35 Some encoding code examples.

---

Python3 vs Pypy3 running threefive

• ( You have to unmute the audio )

https://github.com/user-attachments/assets/9e88fb38-6ad0-487a-a801-90faba9d72c6

---

Using the library

• Let me show you how easy threefive is to use.

• reading SCTE-35 xml from a file

a@fu:~/threefive$ pypy3
Python 3.9.16 (7.3.11+dfsg-2+deb12u3, Dec 30 2024, 22:36:23)
[PyPy 7.3.11 with GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>> from threefive import reader
>>>> from threefive import Cue
>>>> data =reader('/home/a/xml.xml').read()

• load it into a threefive.Cue instance

>>>> cue = Cue(data)

• Show the data as JSON

>>>> cue.show()
{
    "info_section": {
        "table_id": "0xfc",
        "section_syntax_indicator": false,
        "private": false,
        "sap_type": "0x03",
        "sap_details": "No Sap Type",
        "section_length": 92,
        "protocol_version": 0,
        "encrypted_packet": false,
        "encryption_algorithm": 0,
        "pts_adjustment": 0.0,
        "cw_index": "0x00",
        "tier": "0x0fff",
        "splice_command_length": 15,
        "splice_command_type": 5,
        "descriptor_loop_length": 60,
        "crc": "0x7632935"
    },
    "command": {
        "command_length": 15,
        "command_type": 5,
        "name": "Splice Insert",
        "break_auto_return": false,
        "break_duration": 180.0,
        "splice_event_id": 1073743095,
        "splice_event_cancel_indicator": false,
        "out_of_network_indicator": true,
        "program_splice_flag": false,
        "duration_flag": true,
        "splice_immediate_flag": false,
        "event_id_compliance_flag": true,
        "unique_program_id": 1,
        "avail_num": 12,
        "avails_expected": 5
    },
    "descriptors": [
        {
            "tag": 0,
            "identifier": "CUEI",
            "name": "Avail Descriptor",
            "provider_avail_id": 12,
            "descriptor_length": 8
        },
        {
            "tag": 0,
            "identifier": "CUEI",
            "name": "Avail Descriptor",
            "provider_avail_id": 13,
            "descriptor_length": 8
        },
      

    ]
}

• convert the data back to xml

>>>> print(cue.xml())
<scte35:SpliceInfoSection xmlns:scte35="https://scte.org/schemas/35"  ptsAdjustment="0" protocolVersion="0" sapType="3" tier="4095">
   <scte35:SpliceInsert spliceEventId="1073743095" spliceEventCancelIndicator="false" spliceImmediateFlag="false" eventIdComplianceFlag="true" availNum="12" availsExpected="5" outOfNetworkIndicator="true" uniqueProgramId="1">
      <scte35:BreakDuration autoReturn="false" duration="16200000"/>
   </scte35:SpliceInsert>
   <scte35:AvailDescriptor providerAvailId="12"/>
   <scte35:AvailDescriptor providerAvailId="13"/>
   <scte35:AvailDescriptor providerAvailId="14"/>
   <scte35:AvailDescriptor providerAvailId="15"/>
   <scte35:AvailDescriptor providerAvailId="16"/>
   <scte35:AvailDescriptor providerAvailId="17"/>
</scte35:SpliceInfoSection>

• convert to xml+binary

>>>> print(cue.xmlbin())
<scte35:Signal xmlns:scte35="https://scte.org/schemas/35">
    <scte35:Binary>/DBcAAAAAAAAAP/wDwVAAAT3f69+APcxQAABDAUAPAAIQ1VFSQAAAAwACENVRUkAAAANAAhDVUVJAAAADgAIQ1VFSQAAAA8ACENVRUkAAAAQAAhDVUVJAAAAEQdjKTU=</scte35:Binary>
</scte35:Signal>

• convert to base64

>>>> print(cue.base64())
/DBcAAAAAAAAAP/wDwVAAAT3f69+APcxQAABDAUAPAAIQ1VFSQAAAAwACENVRUkAAAANAAhDVUVJAAAADgAIQ1VFSQAAAA8ACENVRUkAAAAQAAhDVUVJAAAAEQdjKTU=

• convert to hex

>>>> print(cue.hex())
0xfc305c00000000000000fff00f05400004f77faf7e00f7314000010c05003c0008435545490000000c0008435545490000000d0008435545490000000e0008435545490000000f000843554549000000100008435545490000001107632935

• show just the splice command

>>>> cue.command.show()
{
    "command_length": 15,
    "command_type": 5,
    "name": "Splice Insert",
    "break_auto_return": false,
    "break_duration": 180.0,
    "splice_event_id": 1073743095,
    "splice_event_cancel_indicator": false,
    "out_of_network_indicator": true,
    "program_splice_flag": false,
    "duration_flag": true,
    "splice_immediate_flag": false,
    "event_id_compliance_flag": true,
    "unique_program_id": 1,
    "avail_num": 12,
    "avails_expected": 5
}

• edit the break duration

>>>> cue.command.break_duration=30
>>>> cue.command.show()
{
    "command_length": 15,
    "command_type": 5,
    "name": "Splice Insert",
    "break_auto_return": false,
    "break_duration": 30,
    "splice_event_id": 1073743095,
    "splice_event_cancel_indicator": false,
    "out_of_network_indicator": true,
    "program_splice_flag": false,
    "duration_flag": true,
    "splice_immediate_flag": false,
    "event_id_compliance_flag": true,
    "unique_program_id": 1,
    "avail_num": 12,
    "avails_expected": 5
}

• re-encode to base64 with the new duration

>>>> cue.base64()
'/DBcAAAAAAAAAP/wDwVAAAT3f69+ACky4AABDAUAPAAIQ1VFSQAAAAwACENVRUkAAAANAAhDVUVJAAAADgAIQ1VFSQAAAA8ACENVRUkAAAAQAAhDVUVJAAAAEe1FB6g='

• re-encode to xml with the new duration

>>>> print(cue.xml())
<scte35:SpliceInfoSection xmlns:scte35="https://scte.org/schemas/35"  ptsAdjustment="0" protocolVersion="0" sapType="3" tier="4095">
   <scte35:SpliceInsert spliceEventId="1073743095" spliceEventCancelIndicator="false" spliceImmediateFlag="false" eventIdComplianceFlag="true" availNum="12" availsExpected="5" outOfNetworkIndicator="true" uniqueProgramId="1">
      <scte35:BreakDuration autoReturn="false" duration="2700000"/>
   </scte35:SpliceInsert>
   <scte35:AvailDescriptor providerAvailId="12"/>
   <scte35:AvailDescriptor providerAvailId="13"/>
   <scte35:AvailDescriptor providerAvailId="14"/>
   <scte35:AvailDescriptor providerAvailId="15"/>
   <scte35:AvailDescriptor providerAvailId="16"/>
   <scte35:AvailDescriptor providerAvailId="17"/>
</scte35:SpliceInfoSection>

• show just the descriptors

>>>> _ = [d.show() for d in cue.descriptors]
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 12,
    "descriptor_length": 8
}
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 13,
    "descriptor_length": 8
}
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 14,
    "descriptor_length": 8
}
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 15,
    "descriptor_length": 8
}
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 16,
    "descriptor_length": 8
}
{
    "tag": 0,
    "identifier": "CUEI",
    "name": "Avail Descriptor",
    "provider_avail_id": 17,
    "descriptor_length": 8
}

• pop off the last descriptor and re-encode to xml

>>>> cue.descriptors.pop()
{'tag': 0, 'identifier': 'CUEI', 'name': 'Avail Descriptor', 'private_data': None, 'provider_avail_id': 17, 'descriptor_length': 8}
>>>> print(cue.xml())
<scte35:SpliceInfoSection xmlns:scte35="https://scte.org/schemas/35"  ptsAdjustment="0" protocolVersion="0" sapType="3" tier="4095">
   <scte35:SpliceInsert spliceEventId="1073743095" spliceEventCancelIndicator="false" spliceImmediateFlag="false" eventIdComplianceFlag="true" availNum="12" availsExpected="5" outOfNetworkIndicator="true" uniqueProgramId="1">
      <scte35:BreakDuration autoReturn="false" duration="2700000"/>
   </scte35:SpliceInsert>
   <scte35:AvailDescriptor providerAvailId="12"/>
   <scte35:AvailDescriptor providerAvailId="13"/>
   <scte35:AvailDescriptor providerAvailId="14"/>
   <scte35:AvailDescriptor providerAvailId="15"/>
   <scte35:AvailDescriptor providerAvailId="16"/>
</scte35:SpliceInfoSection>

[ The Cli tool ]

The cli tool installs automatically with pip or the Makefile.

• SCTE-35 Inputs
• SCTE-35 Outputs
• Parse MPEGTS streams for SCTE-35
• Parse SCTE-35 in hls
• Display MPEGTS iframes
• Display raw SCTE-35 packets from video streams
• Repair SCTE-35 streams changed to bin data by ffmpeg

Inputs

• Most inputs are auto-detected.
• stdin is auto selected and auto detected.
• SCTE-35 data is printed to stderr
• stdout is used when piping video
• mpegts can be specified by file name or URI.

threefive udp://@235.2.5.35:3535

• If a file comtains a SCTE-35 cue as a string( base64,hex,int,json,or xml+bin), redirect the file contents.

  threefive < json.json  

• quoted strings(( base64,hex,int,json or xml+bin), can be passed directly on the command line as well.

threefive '/DAWAAAAAAAAAP/wBQb+ztd7owAAdIbbmw=='

Input Type	Cli Example
Base64	threefive '/DAsAAAAAyiYAP/wCgUAAAABf1+ZmQEBABECD0NVRUkAAAAAf4ABADUAAC2XQZU='
Hex	threefive 0xfc301600000000000000fff00506fed605225b0000b0b65f3b
HLS	threefive hls https://example.com/master.m3u8
JSON	threefive < json.json
Xmlbin	js threefive < xmlbin.xml

Streams

Protocol	Cli Example
File	threefive video.ts
Http(s)	threefive https://example.com/video.ts
Stdin	threefive < video.ts
UDP Multicast	threefive udp://@235.35.3.5:9999
UDP Unicast	threefive udp://10.0.0.7:5555
HLS	threefive hls https://example.com/master.m3u8

Outputs

• output type is determined by the key words base64, bytes, hex, int, json, and xmlbin.
• json is the default.
• Any input (except HLS,) can be returned as any output
  • examples Base64 to Hex etc...)

Output Type	Cli Example
Base 64	threefive 0xfc301600000000000000fff00506fed605225b0000b0b65f3b base64
Bytes	threefive 0xfc301600000000000000fff00506fed605225b0000b0b65f3b bytes
Hex	threefive '/DAsAAAAAyiYAP/wCgUAAAABf1+ZmQEBABECD0NVRUkAAAAAf4ABADUAAC2XQZU=' hex
Integer	threefive '/DAsAAAAAyiYAP/wCgUAAAABf1+ZmQEBABECD0NVRUkAAAAAf4ABADUAAC2XQZU=' int
JSON	threefive 0xfc301600000000000000fff00506fed605225b0000b0b65f3b json
Xml+bin	threefive 0xfc301600000000000000fff00506fed605225b0000b0b65f3b xmlbin

hls

• parse hls manifests and segments for SCTE-35

threefive hls https://example.com/master.m3u8

---

Iframes

• Show iframes PTS in an MPEGTS video

threefive iframes https://example.com/video.ts

---

packets

• Print raw SCTE-35 packets from multicast mpegts video

threefive packets udp://@235.35.3.5:3535

---

proxy

• Parse a https stream and write raw video to stdout

threefive proxy video.ts

---

pts

• Print PTS from mpegts video

threefive pts video.ts

---

sidecar

• Parse a stream, write pts,write SCTE-35 Cues to sidecar.txt

threefive sidecar video.ts

---

sixfix

• Fix SCTE-35 data mangled by ffmpeg

threefive sixfix video.ts

---

show

• Probe mpegts video ( kind of like ffprobe )

 threefive show video.ts

---

version

• Show version

 threefive version

---

help

• Help

 threefive help

---

[ threefive Streams Multicast, it's easy. ]

• The threefive cli has long been a Multicast Receiver( client )
• The cli now comes with a builtin Multicast Sender( server).
• It's optimized for MPEGTS (1316 byte Datagrams) but you can send any video or file.
• The defaults will work in most situations, you don't even have to set the address.
• threefive cli also supports UDP Unicast Streaming.

If you're tired of configuring strange kernel settings with sysctl trying to get multicast to work,
threefive multicast is written from scratch in raw sockets and autoconfigures most settings,
threefive adjusts the SO_RCVBUF, SO_SNDBUF, SO_REUSEADDR,SO_REUSEPORT,IP_MULTICAST_TTL and IP_MULTICAST_LOOP for you.
all you really need to do is make sure multicast is enabled on the network device, threefive can handle the rest.

ip link set wlp2s0  multicast on

a@fu:~$ threefive mcast help
usage: threefive mcast [-h] [-i INPUT] [-a ADDR] [-b BIND_ADDR] [-t TTL]

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT, --input INPUT
                        like "/home/a/vid.ts" or "udp://@235.35.3.5:3535" or
                        "https://futzu.com/xaa.ts"
                        [default:sys.stdin.buffer]
  -a ADDR, --addr ADDR  Destination IP:Port [default:235.35.3.5:3535]
  -b BIND_ADDR, --bind_addr BIND_ADDR
                        Local IP to bind [default:0.0.0.0]
  -t TTL, --ttl TTL     Multicast TTL (1 - 255) [default:32]
a@fu:~$ 

• the video shows three streams being read and played from threefive's multicast, one stream is being converted to srt.
• the command

a@fu:~/scratch/threefive$ threefive mcast -i ~/mpegts/ms.ts 

https://github.com/user-attachments/assets/df95b8da-5ca6-4bf3-b029-c95204841e43

• threefive mcast sends 1316 byte datagrams. Here's tcpdump multicastoutput.

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iodisco.com/scte35

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Install |SCTE-35 Cli | SCTE-35 HLS | Cue Class | Stream Class | Online SCTE-35 Parser | Encode SCTE-35 | SCTE-35 Examples | SCTE-35 XML and More XML | threefive runs Four Times Faster on pypy3 | SuperKabuki SCTE-35 MPEGTS Packet Injection