Fix HEVC TS extra data construction for 3-byte start codes

[kontell]

Description

The VPS/SPS/PPS copy assumed 4-byte start codes on both ends, so with 3-byte start codes it prepended a stray byte (extra data misdetected as hvcC) and truncated the NAL's last byte (corrupt PPS). Emit a clean Annex-B start code and copy only the NAL, mirroring the H.264 path.

Motivation and context

Playback of 4k HEVC streams is failing with inputstream.adaptive while working with inputstream.ffmpegdirect.

This is a demuxer bug, independent of and complementary to xbmc/xbmc#28103. #28103 fixes Kodi's VAAPI path allocating 8-bit (NV12) surfaces for 10-bit HEVC; this fixes the invalid HEVC extra data emitted by the MPEG-TS demuxer. Software decoding plays on both platforms - it's the hardware paths that fail, for different reasons:

• Android (MediaCodec): the invalid extra data is fatal - CBitstreamConverter mis-detects it as hvcC and can't convert.
• Linux (VAAPI): this fix clears the extra-data parse error, but #28103 is still needed for the 10-bit surface (error 18).

[Android / MediaCodec — invalid extra data is fatal here]
2026-06-15 13:08:12.407 T:12836 error <general>: CBitstreamConverter::Convert: error converting.
2026-06-15 13:08:12.407 T:12836 debug <general>: CDVDVideoCodecAndroidMediaCodec::AddData: waiting for keyframe (bitstream)
2026-06-15 13:08:12.418 T:12836 debug <general>: CDVDVideoCodecAndroidMediaCodec::AddData current state (2)

[Linux / ffmpeg — the invalid extra data this PR fixes]
2026-06-15 13:27:42.562 T:1837798 error <general>: ffmpeg[0x55c873bf0880]: [hevc] log2_parallel_merge_level_minus2 out of range: -1

[Linux / VAAPI — separate 10-bit surface fault, fixed by xbmc/xbmc#28103]
2026-06-15 13:18:24.888 T:1836092 error <general>: ffmpeg[0x55c8734a6be0]: [hevc] Failed to end picture decode issue: 18 (invalid parameter).
2026-06-15 13:18:24.888 T:1836092 error <general>: ffmpeg[0x55c8734a6be0]: [hevc] hardware accelerator failed to decode picture
2026-06-15 13:18:24.888 T:1836092 error <general>: GetPicture - avcodec_receive_frame returned failure

How has this been tested?

A test build for Android V22 was created and playback is now successful.

On Linux, without PR28103, the parallel_merge error is removed but playback still fails.

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• I have read the Contributing document
• My code follows the Code Guidelines of this project
• My change requires a change to the Wiki documentation
• I have updated the documentation accordingly

[kodiai]

Decision: APPROVE

Issues: none

Evidence:

• Review prompt covered 2 changed files.

Review Details

• Review plan: ready hash=32fc35de8979 route=standard task=review.full files=2 lines=82(local-diff) budget=na/759s gates=3/3 publish=canonical-visible-surface graph=skipped candidates=preferred doctrine=disabled/0/0/0 reasons=disabled

• Review reducer: ready input=1 kept=1 suppressed=0 rewritten=0 deprioritized=0 lowConfidence=0 auditEvents=0 severityDemoted=0 graphValidated=0 graphUncertain=0 doctrine=disabled/0/0/0 reasons=disabled

• Review candidates: shadow recorded=1 rejected=0 errors=0 artifact=present repo=xbmc-inputstream.adaptive pr=2057 key=kodiai-review-output:v1:inst-109141824:xbmc-inputstream.adaptive:pr-2057:action- delivery=4245da80-68cb-11f1-8ab2-aaf9e5f9eb1b

• Review candidate publication: mode=blocked approved=1 rewritten=0 publishable=0 nonPublishable=1 fixBlocked=1 published=0 directFallback=0 reasons=fix-eligibility-blocked movedToDetails=0 detailsOmitted=0 buckets=blocked:1:fix-eligibility-blocked+missing-replacement

• M072 candidate publication bridge: status=denied; bridgeVersion=candidate-publication-bridge.v1; bridgeId=candidate-publication-record:724bdd2998443d4a5c058003980e2c9c; recordKey=candidate-publication-record:724bdd2998443d4a5c058003980e2c9c; correlationKey=candidate-publication-bridge:0795c19788339fa02320215250a37ad0; source=review-handler-publication; candidateRef=candidate-publication-summary-fc340c0a; verification=none; counts=candidateCount:0,evidenceCount:0,verifiedCount:0,partiallyVerifiedCount:0,unverifiedCount:0,disprovenCount:0,publicationEligibleCount:0,malformedRecordCount:0,unsafeInputFieldCount:0; reasons=no-evidence,publication-ineligible; malformed=none; presence=deliveryId:y,reviewOutputKey:y,upstreamCorrelationKey:y,policyCorrelationKey:y; handoffOwner=available; redaction=privateOnly:y,rawPayloads:n,publicationFields:n,evidencePayloads:n,githubCommentBody:n,reducerRawPayload:n,discardedRawPayload:n,discardedPublicationFields:n,discardedEvidencePayloads:n

• Review finding lifecycle: status=normalized; counts=input:1,recorded:1,rejected:0,unsafeInputFields:0; correlation=repo:y,pull:y,reviewOutputKey:y,deliveryId:y,commit:y; statuses=detected:1,open:1,suggested:0,validated:0,revalidated:0,resolved:0,blocked:0,degraded:0; severity=critical:0,major:1,medium:0,minor:0; actionability=actionable:0,needs-human-review:1,needs-reproduction:0,blocked:0,not-actionable:0; reasons=automatic-detected,automatic-open,automatic-review; rejected=none; redaction=privateOnly:y,rawPrompts:n,rawModelOutput:n,candidateBodies:n,toolPayloads:n,secretLike:n,diffs:n,unboundedArrays:n,unsafeFields:0

• Review validation truth: status=normalized; counts=detected:1,suggested:0,validated:0,revalidated:0,resolved:0,blocked:0,degraded:0,open:1,uncertain:0,inputFindings:1,unsafeInputFields:0; evidence=fresh:0,stale:0,missingValidation:1,missingRevalidation:1; reasons=validation-missing:1; refs=rfl-aaf490d666de13a6:open:validation-missing:fix:n:validation:n:revalidation:n; correlation=reviewOutputKey:y,deliveryId:y; redaction=privateOnly:y,rawPrompts:n,rawModelOutput:n,candidateBodies:n,replacementText:n,toolPayloads:n,secretLike:n,diffs:n,unboundedArrays:n,unsafeFields:0

• Files reviewed: 2

• Findings: 0 critical, 0 major, 0 medium, 0 minor

• Lines changed: +41 -41

• Profile: strict (auto, lines changed: 82)

• Contributor experience: profile-backed (using linked contributor profile guidance)

• Shadow specialist: lane=docs-config-truth status=skipped reason=no-operator-truth-paths candidateCount=0 decisionCount=0 decisionCounts=candidate:0,duplicate:0,disagreement:0,dismissed:0,unclassifiable:0 duplicateCount=0 disagreementCount=0 dismissedCount=0 unclassifiableCount=0 truncatedCandidateCount=0 metricAvailability=token:n,cost:n,latency:n visiblePublicationDenied=true approvalPublicationDenied=true privateOnly=true shadowOnly=true redacted=raw:n,publication:n,approval:n,unsafe:0 correlationKey=669bd02a4d4d9ad6 deliveryId=4245da80-68cb-11f1-8ab2-aaf9e5f… reviewOutputKey=kodiai-review-output:v1:inst-10…

• Review completed: 2026-06-15T15:11:36.256Z

• Total wall-clock: 8m 53s

• Phase timings:

  • queue wait: 0ms
  • workspace preparation: 1.3s
  • retrieval/context assembly: 5.2s
  • executor handoff: 33s
  • remote runtime: 8m 7s
  • publication: 3.3s

• Tokens: 178 in / 24,565 out | 0.7275

• Keyword parsing: No keywords detected

• Budget behavior: complete (within-budget).

• Prompt budget: 5 sections, 0 trimmed, 0 bypassed, 0 trimmed tokens.

• Cache behavior: 2 observations, 1 hits, 1 misses, 0 degraded, 0 bypassed.

• Continuation behavior: 0 observations, 0 compacted, 0 fallback, 0 degraded, 0 bypassed.

[CastagnaIT]

thank you for the fix
please address the code comments

[kontell]

Thanks for the comments, those four have been addressed with the latest push.

[CastagnaIT]

@kodiai review

[kodiai]

Decision: APPROVE

Issues: none

Evidence:

• Review prompt covered 2 changed files.
• Repo inspection tools were used to verify the changed code.
• Review finding lifecycle: status=normalized; counts=input:0,recorded:0,rejected:0,unsafeInputFields:0; statuses=detected:0,open:0,validated:0,degraded:0; severity=critical:0,major:0,medium:0,minor:0; actionability=actionable:0,needs-human-review:0,blocked:0; rejected=none; redaction=privateOnly:y,rawPrompts:n,rawModelOutput:n,candidateBodies:n,toolPayloads:n,secretLike:n,diffs:n,unboundedArrays:n,unsafeFields:0