fix: Disable FEC and RTX in WHEP output to prevent bandwidth doubling - #216
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webrtcsink enables FEC (Forward Error Correction) and RTX (retransmission) by default, which can nearly double bandwidth usage for high-bitrate streams. For a 10 Mbit/s pre-encoded H.264 stream: - Before fix: ~21 Mbit/s transmitted (FEC + RTX overhead) - After fix: ~11 Mbit/s transmitted (expected with RTP overhead) Also includes defensive deduplication of codec caps when relaxing profile matching to prevent potential duplicate stream issues. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
birme
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Feb 2, 2026
…Eyevinn#216) webrtcsink enables FEC (Forward Error Correction) and RTX (retransmission) by default, which can nearly double bandwidth usage for high-bitrate streams. For a 10 Mbit/s pre-encoded H.264 stream: - Before fix: ~21 Mbit/s transmitted (FEC + RTX overhead) - After fix: ~11 Mbit/s transmitted (expected with RTP overhead) Also includes defensive deduplication of codec caps when relaxing profile matching to prevent potential duplicate stream issues. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Per Enstedt <per.enstedt@svt.se> Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
srperens
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Jun 5, 2026
PR #216 disabled both FEC and RTX to stop bandwidth doubling on high-bitrate pre-encoded streams. The doubling came from FEC's constant proactive redundancy — RTX was disabled alongside it without being the culprit. RTX is reactive: it costs nothing while no packets are lost and only resends the exact packets the client NACKs. Without RTX, client NACKs go unanswered, so every burst loss escalates to PLI -> forced keyframe, leaving the picture broken until the keyframe arrives (observed as fps drops from 50 to 3-9 in client stats). Field-verified on a lossy viewer path: with RTX enabled the client holds 44-50 fps through loss bursts and only ~1 in 5 bursts still escalates to PLI, at a retransmission cost proportional to actual loss (zero on clean paths). Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Problem
For a 10 Mbit/s pre-encoded H.264 stream sent via WHEP:
Changes
do-fec=falseanddo-retransmission=falseon whepserversinkTest plan
🤖 Generated with Claude Code