Introduction

Owned by Alon Men
Last updated: 05 Feb 2024
3 min read

Zixi Broadcaster's live transcoding offers a single solution for the universal origination and distribution of high quality, adaptive live broadcast content to OTT workflows, digital MVPDs, MSOs, hotels, cinemas, iPhone and Android player apps as well as other destinations. The Zixi Transcoder supports H.265/HEVC, H.264/AVC, and MPEG2, and Raw video codecs as well as a variety of audio codecs (e.g. AAC, OPUS, Raw) most commonly used for live broadcast and OTT workflows. For OTT and Social Media/eSports, the transcoder can repackage a live stream to HLS, DASH, and RTMP, backhaul via Zixi protocol, and output MPEG-TS, RTP, UDP, NDI, and WebRTC for reintegration into broadcast systems.

With the Zixi transcoder you can:

  • Deliver to any device anywhere in different bitrates and protocols simultaneously
  • Repackage streams to a variety of formats and protocols including MPEG 2, H.264, HEVC encode and decode
  • Synchronize GOPs for multi-bitrate delivery

The transcoder is typically employed in the following cases:

  • Where a target device does not support the source format.
  • Where a target has limited storage capacity that requires a reduced file size.
  • To convert incompatible obsolete data to a better-supported or modern format.
  • You can add video (H.264, H.265, MPEG2, Raw) and audio (AAC, OPUS, Raw) profiles.

Typical Workflows

Typical workflows for the Zixi transcoder include:

  • Broadcast backhaul – Compress high bitrate live mezzanine MPEG2 to lower bitrate H264 or H265, at the same quality level, to reduce bandwidth requirements for video uplink. When uplink bandwidth is scarce or cost is at a premium, compression of live content can make possible an otherwise impractical workflow.
  • Adaptive Bitrate (ABR) – Deliver live mezzanine video transcoded into multiple renditions of H264 or H265 and packaged into HLS or DASH formats to laptops, mobile devices and set top boxes via Content Delivery Networks, YouTube Live or similar services. Adaptive streams can also be delivered via the Zixi protocol to Zixi enabled endpoints.
  • Bitrate reduction and packaging for Social Media – Deliver live mezzanine video transcoded to lower bitrate H264 and packaged into RTMP or HLS to Social Media sites such as Facebook Live, YouTube Live, and Twitch.

Transcoding Options

The transcoding feature in the Zixi Broadcaster is available using the following transcoding options:

  • Software-based codec - uses the AVCODEC library for video decode and x264 library for video encode.
  • NVIDIA GPU-based codec - used nvdec and nvenc libraries and is available in PCIe boards for bare-metal installations and on cloud providers such as AWS, Google Cloud Platform, and Azure.

Ad Insertion Options

Zixi's transcoder supports the following ad insertion options:

  • SCTE-35 passthrough to Zixi TS
  • SCTE-35 converted to CUE-OUT/CUE-IN in HLS
  • SCTE-35 converted to Splice Events in DASH
  • SCTE-35 converted to OnCuePoint in RTMP
  • API Injection with output to SCTE-35 in Zixi TS
  • API Injection with output to CUE-OUT/CUE-IN in HLS
  • API Injection with output to Splice Events in DASH
  • API Injection with output to OnCuePoint in RTMP

Captioning Options

Zixi's transcoder supports the following captioning options:

  • ATSC 608/708 ES passthrough to Zixi TS, HLS, DASH, and RTMP
  • DVB track passthrough to Zixi TS
  • WebVTT generation from ATSC 708 Elementary Stream

Audio Processing Options

  • Transcode up to 16 audio tracks
  • Passthrough of multiple audio tracks
  • Passthrough of unsupported codecs such as E-AC-3
  • Audio Sample Rate Conversion - 44.1KHz to/from 48KHz
  • PID mapping of audio tracks

Audio Decode

  • AAC Low Complexity, High Efficiency V1, High Efficiency V2
  • AC3 (Dolby Digital)
  • MP2 (MPEG-2 Audio Layer II)
  • MP1 (MPEG-1 Audio Layer II)
  • Opus

Audio Encode

  • AAC Low Complexity
  • AAC High Efficiency V1
  • AAC High Efficiency V2
  • E-AC-3 (Enhanced Dolby Digital)
  • MP1 (MPEG-1 Audio Layer II)
  • Opus

Video Processing

  • MPTS De-multiplexing
  • Passthrough
  • 10-bit to 8-bit color downscaling
  • Thumbnail extraction as HLS playlist
  • Deinterlacing (except telecine 60i/59.94i to 24p)
  • Interlaced and progressive output with software
  • Progressive output with NVIDIA
  • Smooth up/down framerate conversion with frame interpolation with NVIDIA
  • Frame duplication/removal framerate conversion with software
  • PID mapping and PID pass-thru
  • Preserve aspect ratio with black bar insertion
  • Cropping
  • Static image overlay/logo Insertion
  • Dynamic HTML overlay
  • Copy GOP from source or generate new GOP
  • GOP synchronization when generate new GOP
  • Omit or keep closed captions
  • I-frame synchronization of outputs with different FPS
  • I-frame injection at SCTE-35 markers
  • Preserve all video source color primaries