Jaap Valkhoff
type: MusicGroup
genre: polka
description: thumb| Jacobus (Jaap) Valkhoff (16 August 1910 in Rotterdam – 3 July 1992 in Hook of Holland) was a Dutch musician, composer and lyricist. He wrote his most famous lyrics in 1961 at the request of J
popularity: 11
followers: 967
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additional property: CopyrightChainExplorerURL
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additional property: OTSBitcoinBlock
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additional property: OTSCanonicalRecord
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additional property: OTSVerifyInstructions
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  value: 1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
subject of: OpenTimestamps Proof of Existence
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  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4e88670065fedb84b7792263a6ae333f4280ba0f775f49506cc5e2b875dbdf16. Chain 2 (Bitcoin): anchored in block 953778 (2026-06-15T11:57:35Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/d4538dc1-40ba-40fb-95b0-718d7052551c.json and https://artists.proofprofile.net/proofs/artist/d4538dc1-40ba-40fb-95b0-718d7052551c.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
  date published: 2026-06-15T11:57:35Z
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album: Wil Je Een Hups / Ome Jan, De Trombonist
  type: MusicAlbum
  date published: 1964-09-19
album: 14 Tango's
  type: MusicAlbum
  date published: 1972-11-07
album: Met Rotterdamse Riet In Het Havencafé (Live)
  type: MusicAlbum
  date published: 1972-12-04
album: Diep in Mijn Hart
  type: MusicAlbum
  date published: 1996-05-01
album: Diep in Mijn Hart
  type: MusicAlbum
  date published: 1996-06-01
  track: Langs de maas
    type: MusicRecording
    duration: PT3M25S
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    by artist: Jaap Valkhoff
    in album: Diep in Mijn Hart
      type: MusicAlbum
      date published: 1996-06-01
    genre: polka
    isrc code: NLA539619012
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    additional property: OTSVerificationAPI
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    additional property: OTSTimestamp
      type: PropertyValue
      value: 2026-07-02T16:51:38Z
    additional property: OTSVerifyInstructions
      type: PropertyValue
      value: 1. Confirm isrcCode identifies the recording in the pre-2022 source corpus and cc-db-prod record 2. GET OTSVerificationAPI → server-side canonical-record, hash, and attestation checks must pass 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Confirm CopyrightID is the CopyrightChains transaction hash 5. If all match: the cc-db-prod record is independently anchored on Bitcoin at OTSTimestamp Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
    subject of: OpenTimestamps Proof of Existence
      type: DigitalDocument
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      description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa2d8961bd4f994a2506eb55126a68e8f4547341e37f860db74c96a80f886db70. Chain 2 (Bitcoin): anchored in block 956375 (2026-07-02T16:51:38Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLA539619012.
      date published: 2026-07-02T16:51:38Z
    audio: Langs de maas
      type: AudioObject
      additional property: Tempo (BPM)
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        value: 83.546
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      additional property: Mode (Major/Minor)
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        value: 1
      additional property: Time Signature
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      additional property: Danceability
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      additional property: Energy
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      additional property: Speechiness
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      additional property: Acousticness
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      additional property: Instrumentalness
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      additional property: Liveness
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        value: 0.141
      additional property: Valence (Positivity)
        type: PropertyValue
        value: 0.272
      additional property: Loudness (dB)
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      additional property: Key Name
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        value: F
      additional property: Mode Name
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  track: Japie de portier
    type: MusicRecording
    duration: PT2M27S
    duration ms: 147546
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    by artist: Jaap Valkhoff
    in album: Diep in Mijn Hart
      type: MusicAlbum
      date published: 1996-06-01
    genre: polka
    isrc code: NLA539619013
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    additional property: OTSTimestamp
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      value: 2026-07-21T15:22:58Z
    additional property: OTSVerifyInstructions
      type: PropertyValue
      value: 1. Confirm isrcCode identifies the recording in the pre-2022 source corpus and cc-db-prod record 2. GET OTSVerificationAPI → server-side canonical-record, hash, and attestation checks must pass 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Confirm CopyrightID is the CopyrightChains transaction hash 5. If all match: the cc-db-prod record is independently anchored on Bitcoin at OTSTimestamp Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
    subject of: OpenTimestamps Proof of Existence
      type: DigitalDocument
      encoding format: application/vnd.opentimestamps.ots
      description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1f62e90ad8aa22f373fba039f0271f2f106639493c80564527fecf98dfd13d18. Chain 2 (Bitcoin): anchored in block 959023 (2026-07-21T15:22:58Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLA539619013.
      date published: 2026-07-21T15:22:58Z
    audio: Japie de portier
      type: AudioObject
      additional property: Tempo (BPM)
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        value: 129.756
      additional property: Musical Key
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        value: 8
      additional property: Mode (Major/Minor)
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        value: 1
      additional property: Time Signature
        type: PropertyValue
        value: 3
      additional property: Danceability
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      additional property: Energy
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        value: 0.448
      additional property: Speechiness
      additional property: Acousticness
      additional property: Instrumentalness
      additional property: Liveness
      additional property: Valence (Positivity)
      additional property: Loudness (dB)
      additional property: Key Name
      additional property: Mode Name
album: Gezelligheid Kent Geen Tijd
album: De Gouden Jaren van Telstar: Jaap Valkhoff

Speechiness
type: PropertyValue
value: 0.138

Acousticness
type: PropertyValue
value: 0.788

Instrumentalness
type: PropertyValue
value: 0

Liveness
type: PropertyValue
value: 0.046

Valence (Positivity)
type: PropertyValue
value: 0.904

Loudness (dB)
type: PropertyValue
value: -12.893

Key Name
type: PropertyValue
value: Ab

Mode Name
type: PropertyValue
value: Major

Gezelligheid Kent Geen Tijd
type: MusicAlbum
date published: 2021-08-20

De Gouden Jaren van Telstar: Jaap Valkhoff
type: MusicAlbum
date published: 2024-10-25