URMI Consortium

Bridging Legacy CATV MP2 Feeds to Modern AAC & MP3 Digital Streaming Workflows

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Open-Source Audio Transcoder & MPTS to SPTS Demuxer | Urmic

Convert high-density CATV MP2 audio feeds to AAC/MP3 for OTT & IPTV. Discover the open-source Urmic Audio Transcoder with full MPTS to SPTS demuxing support.

audio transcoder, open source audio encoder, MPTS to SPTS, MP2 to AAC conversion, IPTV audio transcoder, OTT streaming audio, CATV broadcast conversion

High-Performance, Broadcast-Grade Audio Processing

In modern video distribution architectures, audio codec incompatibility is one of the biggest bottlenecks when bridging traditional cable networks with next-generation digital platforms.

Urmic Audio Transcoder is a robust, open-source audio processing solution engineered for broadcasters, cable operators (MSOs), and IPTV/OTT service providers. Designed for high-density, low-latency environments, it automates the extraction, transcoding, and restreaming of multi-channel audio feeds with minimal CPU overhead.

The Challenge: CATV (MP2) vs. OTT/IPTV (AAC / MP3)

Legacy cable television (CATV/DVB-C) systems rely heavily on the MPEG-1 Audio Layer II (MP2) standard for linear transmission due to legacy set-top box constraints and older broadcast specifications.

However, modern digital streaming environments require updated codecs:

  • OTT Platforms & Mobile Apps: Require AAC (Advanced Audio Coding) or HE-AAC to ensure playback compatibility across iOS, Android, web browsers (HLS/DASH), and Smart TVs.
  • IPTV Middleware & Set-Top Boxes: Expect AAC or MP3 streams to maintain low bitrates while delivering clear acoustic quality.

Directly relaying CATV feeds to OTT or modern IPTV networks results in silent playbacks, decoding errors, or rejected stream ingest.

Urmic Audio Transcoder solves this instantly by ingesting legacy MPEG-2 audio streams and transcoding them in real time to bandwidth-efficient, universally compatible AAC or MP3 formats without touching or degrading the passthrough video stream.

Built-in MPTS to SPTS Demuxing & Filtering

Beyond raw audio encoding, the Urmic Audio Transcoder functions as an efficient MPTS (Multi-Program Transport Stream) to SPTS (Single-Program Transport Stream) splitter.

  CATV MPTS Feed (UDP) -->  Urmic Audio Transcoder  -->  Clean SPTS Feeds (UDP)

Key Demuxing & Routing Features:

  1. PID Extraction: Select specific Video PIDs, Audio PIDs, and PCRs from heavy MPTS satellite or QAM receiver inputs.
  2. Channel Splitting: Demux multi-channel bundles into isolated, single-service UDP/RTP multicast or unicast SPTS streams ready for packagers, origin servers, or edge encoders.
  3. Audio Channel Remapping: Transcode primary and secondary audio tracks (multi-language feeds) simultaneously per channel.

Key Features & Capabilities

  • High-Density Channel Processing: Transcode dozens of concurrent stereo or mono channels per server instance with optimized multi-threading.
  • Universal Codec Support:
    • Inputs: MPEG-1 Layer II (MP2), AC-3 (Dolby Digital), E-AC-3, AAC, MP3, PCM.
    • Outputs: AAC-LC, HE-AAC v1/v2, MP3, Opus, or uncompressed passthrough.
  • Zero Video Degradation: Passthrough mode copies H.264, H.265 (HEVC), or MPEG-2 video packets directly, altering only the designated audio PIDs for zero latency penalty.
  • Stream Protocol Compatibility: Supports standard broadcast protocols including UDP Multicast/Unicast, RTP, SRT, and HTTP TS.
  • Open & Extensible: Fully open-source architecture distributed under the Urmi License, allowing seamless integration into automated headend control scripts and monitoring dashboards.

Technical Specifications

ParameterSpecification Details
Input ProtocolsUDP (Multicast/Unicast), RTP, SRT, HTTP TS
Output ProtocolsUDP Multicast/Unicast, RTP, SRT, Raw ES
Supported Stream TypesMPTS (Multi-Program TS) & SPTS (Single-Program TS)
Supported Input AudioMP2, MP3, AAC-LC, HE-AAC, AC-3, E-AC-3, LPCM
Supported Output AudioAAC-LC, HE-AAC (v1/v2), MP3, Opus
Sample Rates32 kHz, 44.1 kHz, 48 kHz (Auto-resampling supported)
Bitrates32 kbps to 384 kbps (Configurable per PID)
Host EnvironmentUbuntu 24.04.4 LTS (Tested)
Documentation & GuidesAvailable at learn.urmic.org

Complete the Urmic Broadcast Infrastructure

Build a complete end-to-end headend with our companion processing tools:

  • Urmi Universal Encoder / Decoder: The all-in-one hardware and software platform for real-time video capture, distribution, and protocol translation.
  • Urmic MPEG-2 Transcoder: High-density legacy video transcoding to convert heavy MPEG-2 cable feeds into modern H.264/H.265 streams for bandwidth-optimized delivery.

Get Started with Open-Source Transcoding