[ The problem with SCTE-35 and HLS ]

June 11, 2026 ยท View on GitHub

 
	The SCTE-35 spec uses the SCTE35 HLS tags. 
	
	The HLS spec uses the DateRange HLS tags for SCTE-35. 

	The mosty commonly used SCTE-35 HLS tags are actually from an old Adobe specification, 
and not officially acknowledged by the SCTE-35 or HLS spec. 
	
	To make it just a little bit more confusing, SCTE-35 can be also be embedded in the video segments, 
with or without any HLS tags.

Don't worry man, threefive supports HLS SCTE-35 in every way possible.

	Most of the options presented here are for filtering the SCTE-35 data to what you need,
	
	By default, threefive parses everything.

[ threefive hls ]

  • threefive hls is a HLS SCTE-35 parser. It takes a rendition or master m3u8 as input.
  • Automatic AES decryption for segments.
  • Automatic AAC and AC3 ID3 Tag sync safe timestamp header parsing for audio only renditions.
  • SCTE-35 Can be parsed from MPEGTS segments and from m3u8 files.
  • All HLS SCTE-35 tags are supported.
  • threefive hls also allows you to filter SCTE-35 Messages.

[ Help ]

To display this help:

	threefive hls 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

  • Protocols supported:

    • file
    • http(s)
    • UDP
    • Multicast

  • Encryption supported:

    • AES-128 (segments are automatically decrypted)

[ SCTE-35 ]

threefive hls displays SCTE-35 Embedded Cues as well as SCTE-35 HLS Tags.

  • Supported HLS Tags
    • #EXT-OATCLS-SCTE35
    • #EXT-X-CUE-OUT-CONT
    • #EXT-X-DATERANGE
    • #EXT-X-SCTE35
    • #EXT-X-CUE-IN
    • #EXT-X-CUE-OUT

[ SCTE-35 Parsing Profiles ]

SCTE-35 parsing can be fine tuned by setting a parsing profile.

running the command:

        threefive hls profile

will generate a default profile and write a file named hls.profile in the current working directory.

    a@fu:~$ cat hls.profile

    expand_cues = False
    parse_segments = False
    parse_manifests = True
    hls_tags = #EXT-OATCLS-SCTE35,#EXT-X-CUE-OUT-CONT,
    #EXT-X-DATERANGE,#EXT-X-SCTE35,#EXT-X-CUE-IN,#EXT-X-CUE-OUT
    command_types = 0x6,0x5
    descriptor_tags = 0x2
    starts = 0x22,0x30,0x32,0x34,0x36,0x44,0x46

  • Integers are show in hex (base 16), base 10 unsigned integers can also be used.

  • expand_cues: set to True to show cues fully expanded as JSON

  • parse_segments: set to true to enable parsing SCTE-35 from MPEGTS.

  • parse_manifests: set to true to parse the m3u8 file for SCTE-35 HLS Tags.

  • hls_tags: set which SCTE-35 HLS Tags to parse.

  • command_types: set which Splice Commands to parse.

  • descriptor_tags: set which Splice Descriptor Tags to parse.

  • starts: set which Segmentation Type IDs to use to start breaks.

    Edit the file as needed and then run threefive hls.

[ Profile Formatting Rules ]

  • Values do not need to be quoted.
  • Multiple values are separated by a commas.
  • No partial line comments. Comments must be on a separate lines.
  • Comments can be started with a # or //
  • Integers can be base 10 or base 16

[ Output Files ]

  • Created in the current working directory
  • Clobbered on start of showcues
  • Profile rules applied to the output:
  • hls.m3u8 - live playable rewrite of the m3u8 with the profile SCTE-35 rules.
  • hls.sidecar - list of ( pts, HLS SCTE-35 tag ) pairs

Profile rules not applied to the output:

  • hlsflat.m3u8 - hls live streams are flattened out into a vod playlist. When the live m3u8 first loads, every line is written to hlsflat.m3u8 Wnen a live m3u8 is reloaded, everything except the headers is appended to hlsflat.m3u8. This give you a VOD style m3u8 so you can fast forward or rewind while playing. GREAT for debugging SCTE-35 live hls.

[ Cool Features ]

  • threefive hls can resume when started in the middle of an ad break.
            2023-10-13T05:59:50.24Z Resuming Ad Break
            2023-10-13T05:59:50.34Z Setting Break Timer to 17.733
            2023-10-13T05:59:50.44Z Setting Break Duration to 60.067
  • mpegts streams are listed on start ( like ffprobe )
        Program: 1
            Service:
            Provider:
            Pid:	480
            Pcr Pid:	481
            Streams:
                Pid: 481[0x1e1]	Type: 0x1b AVC Video
                Pid: 482[0x1e2]	Type: 0xf AAC Audio
                Pid: 483[0x1e3]	Type: 0x86 SCTE35 Data
                Pid: 484[0x1e4]	Type: 252 Unknown
                Pid: 485[0x1e5]	Type: 0x15 ID3 Timed Meta Data

[ Example Usage ]

  • Show this help:
         threefive hls help
  • Generate a new hls.profile:
        threefive hls profile
  • parse an m3u8:
        threefive  https://example.com/out/master.m3u8