{"observation":{"id":"ea14f7df-bcae-4c53-af53-bc37821e7b99","tool":"descript","tool_name":"Descript","criterion":"sync-accuracy","criterion_name":"Sync Accuracy","criterion_definition":"The effect is timed to the specific action or object rather than playing generically across the whole clip.","criterion_evidence_type":"transformation","criterion_rank_role":"decisive","criterion_rank_role_reason":"Timing the effect to the exact action is essential to believable automated sound design. (3 of 3 judges)","scenario":"bird-nature-video","scenario_name":"Bird/Nature Video","group_tag":"auto-sfx-video-generation","scenario_description":"A video featuring a bird in frame, used to test whether generated chirping or ambient sounds sync to the specific animal and movement shown on screen.","modality":"video","input_text":null,"input_artifact_refs":[],"stresses":["sync accuracy to a visible subject","nature/animal sound matching","avoiding generic ambience that ignores timing","scene-specific audio generation"],"verdict":"failed","score":null,"score_total":null,"note":"On the bird test, the tool failed to sync sound to the animal's actual behavior, playing bird chirping continuously for the full 10-second clip even though the bird chirped only 2–3 times.","evidence_state":"verified","source":null,"artifacts":[{"url":"https://d3epheqghktydj.cloudfront.net/descript-descript-bird-chirping-output-1-010b2e8aa8d8.mp4","role":"output","alt":null}],"run_id":"90451942-9055-4e8c-85e6-17c773437ed7","study_title":"Automatically Add Relevant Sound Effects to Videos","study_kind":"generation","research_task":"86b84w3x5","tested_at":null,"completeness":"output-only","input":{"state":"not-captured","text":null,"files":[],"modality":"video","stresses":["sync accuracy to a visible subject","nature/animal sound matching","avoiding generic ambience that ignores timing","scene-specific audio generation"]},"tool_page_slug":"descript","tool_url":"https://aidemos.com/tools/descript","permalink":"https://aidemos.com/evidence/ea14f7df-bcae-4c53-af53-bc37821e7b99","api_url":"https://ai.aidemos.com/v1/observations/ea14f7df-bcae-4c53-af53-bc37821e7b99"},"peers":[{"id":"3c325f18-9f10-480d-b154-f10498f7f11a","tool":"fine-voice","tool_name":"Fine Voice","verdict":"struggled","score":60.0,"score_total":100.0,"note":"Even with prompt guidance, chirps did not line up with the bird's actual chirping moments; the better bird output was only about 60% satisfying.","artifact_count":4,"thumbnail":"https://d3epheqghktydj.cloudfront.net/research-media-bird-88b167f7f533.mp4","evidence_url":"https://aidemos.com/evidence/3c325f18-9f10-480d-b154-f10498f7f11a"},{"id":"2936e1bf-5a08-4140-8e22-568ab1ab9bae","tool":"flexclip","tool_name":"FlexClip","verdict":"failed","score":null,"score_total":null,"note":"The chirping was not tied to the bird on screen; it played generically instead of syncing to the visible animal's action.","artifact_count":2,"thumbnail":"https://d3epheqghktydj.cloudfront.net/research-media-bird-88b167f7f533.mp4","evidence_url":"https://aidemos.com/evidence/2936e1bf-5a08-4140-8e22-568ab1ab9bae"},{"id":"423601f9-0ef6-48b2-8f30-ecbcf9624efe","tool":"kling-ai","tool_name":"Kling AI","verdict":"failed","score":null,"score_total":null,"note":"The subject-specific sound can fail to line up with the object’s on-screen behavior.","artifact_count":5,"thumbnail":"https://d3epheqghktydj.cloudfront.net/research-media-bird-88b167f7f533.mp4","evidence_url":"https://aidemos.com/evidence/423601f9-0ef6-48b2-8f30-ecbcf9624efe"},{"id":"8edf5ecc-9e2f-40ad-98a9-b81a4dd468bf","tool":"mirelo","tool_name":"Mirelo","verdict":"worked","score":null,"score_total":null,"note":"It can achieve near-perfect timing on natural footage; one variant was reported as so accurately synced that the sound effects seemed like part of the video.","artifact_count":2,"thumbnail":"https://d3epheqghktydj.cloudfront.net/research-media-bird-88b167f7f533.mp4","evidence_url":"https://aidemos.com/evidence/8edf5ecc-9e2f-40ad-98a9-b81a4dd468bf"}],"other_criteria":[{"id":"01bbcafd-073a-4207-842a-549c9dcf2858","criterion":"variant-usefulness","criterion_name":"Variant Usefulness","rank_role":"context","verdict":"mixed","score":null,"score_total":null,"note":"When the bird species is ambiguous, the tool can generate four distinct chirp variants (generic bird chirping, birds chirping, tropical birds, morning birds), which adds some choice, but none of the variants fixes the temporal mismatch.","artifact_count":1,"evidence_url":"https://aidemos.com/evidence/01bbcafd-073a-4207-842a-549c9dcf2858"}],"appears_in":[{"page_type":"ranking","slug":"ai-sound-effect-generators","title":"Best AI Tools to Automatically Add Sound Effects to Videos","url":"https://aidemos.com/best/ai-sound-effect-generators","binding":"run"},{"page_type":"tool","slug":"fine-voice","title":null,"url":"https://aidemos.com/tools/fine-voice","binding":"run"},{"page_type":"tool","slug":"flexclip","title":null,"url":"https://aidemos.com/tools/flexclip","binding":"run"},{"page_type":"tool","slug":"kling-ai","title":null,"url":"https://aidemos.com/tools/kling-ai","binding":"run"},{"page_type":"tool","slug":"mirelo","title":null,"url":"https://aidemos.com/tools/mirelo","binding":"run"}],"same_scenario":[{"id":"3c325f18-9f10-480d-b154-f10498f7f11a","tool":"fine-voice","tool_name":"Fine Voice","verdict":"struggled","score":60.0,"score_total":100.0,"note":"Even with prompt guidance, chirps did not line up with the bird's actual chirping moments; the better bird output was only about 60% satisfying."},{"id":"2936e1bf-5a08-4140-8e22-568ab1ab9bae","tool":"flexclip","tool_name":"FlexClip","verdict":"failed","score":null,"score_total":null,"note":"The chirping was not tied to the bird on screen; it played generically instead of syncing to the visible animal's action."},{"id":"423601f9-0ef6-48b2-8f30-ecbcf9624efe","tool":"kling-ai","tool_name":"Kling AI","verdict":"failed","score":null,"score_total":null,"note":"The subject-specific sound can fail to line up with the object’s on-screen behavior."},{"id":"8edf5ecc-9e2f-40ad-98a9-b81a4dd468bf","tool":"mirelo","tool_name":"Mirelo","verdict":"worked","score":null,"score_total":null,"note":"It can achieve near-perfect timing on natural footage; one variant was reported as so accurately synced that the sound effects seemed like part of the video."}]}