Missing Captions Troubleshooting Guide

missing captions can occur at several points in the signal chain the fastest path to resolution is figuring out where captions disappear step 1 isolate the fault point before changing anything, capture and inspect the stream at each stage source (encoder output) → zixi input → zixi output → decoder/ird use a ts analyzer (wireshark, a hardware analyzer, or vlc with stream info) to check whether captions are present at each stage the point where they vanish is the fault point step 2 check the source encoder if captions are absent from the start of the chain this is likely an issue at the encoder things to check is closed caption passthrough enabled? this is a common miss after a firmware update, reconfiguration, or factory reset is the encoder transcoding the video? transcoding pipelines frequently strip cea 608/708 data unless cc passthrough is configured verify the source material is actually captioned live sports and news feeds typically are, but the caption insertion feed (e g a separate caption encoder) may have its own failure are there frame drops in the encoder logs? cea 608 data rides per frame inside the video elementary stream dropped frames mean dropped caption bytes fix enable cc passthrough in the encoder settings if transcoding, ensure the transcoder is configured to re encode or pass through caption data refer to your encoder vendor's documentation for specific information step 3 check the zixi path if captions are present at the zixi input but missing at the output, something in the broadcaster/zec processing chain is removing them or an error is occurring what to check is any transcoding or remuxing being applied inside zixi broadcaster? this may be inadvertently stripping out the caption data on failover channels, did a source switch occur recently? the backup source may not be configured identically to the primary check that the failover source encoder has the same cc settings review zen master source/channel/target and broadcaster logs around the time captions went missing look for source switch events, errors, or unexpected restarts step 4 check the decoder / ird if captions are present in the zixi output but still not displaying at the endpoint what to check is the decoder configured to decode the correct caption service? cea 608 cc1 or cc3 (field 1/field 2) cea 708 service 1 (most common default) has the decoder been recently rebooted or reconfigured? caption decode settings can reset to defaults does the playout or monitoring system have a caption rendering/overlay setting that may be disabled? troubleshooting decision tree captions reported missing zen master alert raised? → yes → event notification profile has caption monitoring enabled — trace chain below to find fault point captions absent from source ts? → yes → encoder issue (step 2) captions present at zixi input, missing at zixi output? → yes → distribution/processing issue (step 3) captions in zixi output, not displaying at endpoint? → yes → decoder / ird issue (step 4) a clear fault point found? → no → capture ts at input and output and escalate to zixi support zen master event notification alerts if you're using zixi zen master, it can be configured to actively alert on missing captions if your event notification profile has caption monitoring enabled, zen master will raise an error any time captions are not detected in the stream a zen master caption alert is a reliable signal that captions are absent, but it isn't able to tell you why use steps 1–4 above to find the fault point if captions are intentionally not present on a channel (e g a non captioned feed), disable the caption check in the event notification profile for that channel to avoid false alarms check your event notification profile settings in zen master under settings → event notifications to confirm which event types are active and which channels they apply to escalation if captions are confirmed present in the zixi output stream but a downstream device is still not displaying them, provide the following to support ts capture at the zixi output ( ts or pcap) encoder and zixi broadcaster logs covering the affected time window decoder model and firmware version whether the issue is constant or tied to specific events (e g , source switches, time of day)