Willem Pijper
type: MusicGroup
description: Willem Frederik Johannes Pijper (; 8 September 189418 March 1947) was a Dutch composer, music critic and music teacher. Pijper is considered to be among the most important Dutch composers of the first
popularity: 5
followers: 316
additional property: CopyrightID
additional property: CopyrightChainExplorerURL
  type: PropertyValue
  value: https://explorer.copyrightchains.com/tx/0x65d1a7d95d4c7cd11866be8509bdb283a641d165589e2665c127a59e7ae17c95
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 954065
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/954065
additional property: OTSProofURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/48d35c0a-6cad-41b2-a359-3b5dd68eba4e.ots
additional property: OTSRecordURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/48d35c0a-6cad-41b2-a359-3b5dd68eba4e.json
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/artist/48d35c0a-6cad-41b2-a359-3b5dd68eba4e
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-06-17T08:10:43Z
additional property: OTSCanonicalRecord
  type: PropertyValue
  value: {"copyright_id":"0x65d1a7d95d4c7cd11866be8509bdb283a641d165589e2665c127a59e7ae17c95","name":"Willem Pijper","registered_at":"2026-06-16T14:56:48Z","symbol":"NIM1087453","token_address":"0xd5d6e677431ed6fae462705d5f5fc15c1d244b0e","type":"artist","uuid":"48d35c0a-6cad-41b2-a359-3b5dd68eba4e"}
additional property: OTSVerifyInstructions
  type: PropertyValue
  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
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x65d1a7d95d4c7cd11866be8509bdb283a641d165589e2665c127a59e7ae17c95. Chain 2 (Bitcoin): anchored in block 954065 (2026-06-17T08:10:43Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/48d35c0a-6cad-41b2-a359-3b5dd68eba4e.json and https://artists.proofprofile.net/proofs/artist/48d35c0a-6cad-41b2-a359-3b5dd68eba4e.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
  date published: 2026-06-17T08:10:43Z
  text: {"copyright_id":"0x65d1a7d95d4c7cd11866be8509bdb283a641d165589e2665c127a59e7ae17c95","name":"Willem Pijper","registered_at":"2026-06-16T14:56:48Z","symbol":"NIM1087453","token_address":"0xd5d6e677431ed6fae462705d5f5fc15c1d244b0e","type":"artist","uuid":"48d35c0a-6cad-41b2-a359-3b5dd68eba4e"}
album: Pijper & Badings: Concertos and Symphonic Works (Mono Version)
  type: MusicAlbum
  date published: 1963-01-01
album: Willem Pijper
  type: MusicAlbum
  date published: 1970-01-01
album: Pijper: Violin Sonata No. 2 / Cello Sonatas / Piano Trio No. 2
  type: MusicAlbum
  date published: 1970-01-01
album: Pijper: Five String Quartets
  type: MusicAlbum
  date published: 1995-01-01
album: Willem Pijper: Highlights
  type: MusicAlbum
  date published: 2000-01-01
album: Merlijn
  type: MusicAlbum
  date published: 2005-10-24
album: The Dutch Legacy, Vol. 4
  type: MusicAlbum
  date published: 2009-09-01
album: Pijper: Complete Music for Piano - Sonatas for Cello and Piano Nos. 1 & 2
  type: MusicAlbum
  date published: 2016-08-17
track: Sonata for Two Pianos: II. Grave
track: Sonata for Two Pianos: III. Moderato assai
track: Sonata for Two Pianos: I. Allegro aperto, ma pesante

Sonata for Two Pianos: II. Grave
type: MusicRecording
duration: PT4M13S
duration ms: 253733
explicit: false
by artist: Willem Pijper
by artist: Lucas Jussen
by artist: Arthur Jussen
in album: Dutch Masters
  type: MusicAlbum
  date published: 2022-04-29
isrc code: NLK4J2200002
additional property: CopyrightID
additional property: CopyrightStatus
  type: PropertyValue
  value: registered
additional property: CopyrightRegisteredAt
  type: PropertyValue
  value: 2026-07-06T21:13:14+00:00
additional property: CopyrightChainExplorerURL
  type: PropertyValue
  value: https://explorer.copyrightchains.com/tx/0xd58790b5fafe06a100ad89062f0655ab632c6cab6bb667bde458764417a4cec6
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 957118
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/957118
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLK4J2200002
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-07-08T03:20:19Z
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
additional property: ProofProfileEvidenceStatus
  type: PropertyValue
  value: verified-cc-db-prod
additional property: TokenDeploymentConfirmed
  type: PropertyValue
  value: true
additional property: ContentHash
additional property: BitcoinBlock
  type: PropertyValue
  value: 957118
additional property: BitcoinTime
  type: PropertyValue
  value: 2026-07-08T03:20:19+00:00
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd58790b5fafe06a100ad89062f0655ab632c6cab6bb667bde458764417a4cec6. Chain 2 (Bitcoin): anchored in block 957118 (2026-07-08T03:20:19Z), 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/NLK4J2200002.
  date published: 2026-07-08T03:20:19Z
audio: Sonata for Two Pianos: II. Grave
  type: AudioObject
  additional property: Tempo (BPM)
    type: PropertyValue
    value: 111.782
  additional property: Musical Key
    type: PropertyValue
    value: 6
  additional property: Mode (Major/Minor)
    type: PropertyValue
    value: 1
  additional property: Time Signature
    type: PropertyValue
    value: 5
  additional property: Danceability
    type: PropertyValue
    value: 0.305
  additional property: Energy
    type: PropertyValue
    value: 0.014
  additional property: Speechiness
    type: PropertyValue
    value: 0.057
  additional property: Acousticness
    type: PropertyValue
    value: 0.993
  additional property: Instrumentalness
    type: PropertyValue
    value: 0.865
  additional property: Liveness
    type: PropertyValue
    value: 0.089
  additional property: Valence (Positivity)
    type: PropertyValue
    value: 0.038
  additional property: Loudness (dB)
    type: PropertyValue
    value: -29.908
  additional property: Key Name
    type: PropertyValue
    value: F#
  additional property: Mode Name
    type: PropertyValue
    value: Major

Sonata for Two Pianos: III. Moderato assai
type: MusicRecording
duration: PT4M3S
duration ms: 243240
explicit: false
by artist: Willem Pijper
by artist: Lucas Jussen
by artist: Arthur Jussen
in album: Dutch Masters
  type: MusicAlbum
  date published: 2022-04-29
isrc code: NLK4J2200003
additional property: CopyrightID
additional property: CopyrightStatus
  type: PropertyValue
  value: registered
additional property: CopyrightRegisteredAt
  type: PropertyValue
  value: 2026-07-06T09:36:21+00:00
additional property: CopyrightChainExplorerURL
  type: PropertyValue
  value: https://explorer.copyrightchains.com/tx/0xf39d4ec663c3c22fa03ed42ec35b92623d002c36775dd0c7aa5cc34f2bd8b7ee
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 957061
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/957061
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLK4J2200003
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-07-07T16:07:00Z
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
additional property: ProofProfileEvidenceStatus
  type: PropertyValue
  value: verified-cc-db-prod
additional property: TokenDeploymentConfirmed
  type: PropertyValue
  value: true
additional property: ContentHash
additional property: BitcoinBlock
  type: PropertyValue
  value: 957061
additional property: BitcoinTime
  type: PropertyValue
  value: 2026-07-07T16:07:00+00:00
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf39d4ec663c3c22fa03ed42ec35b92623d002c36775dd0c7aa5cc34f2bd8b7ee. Chain 2 (Bitcoin): anchored in block 957061 (2026-07-07T16:07:00Z), 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/NLK4J2200003.
  date published: 2026-07-07T16:07:00Z
audio: Sonata for Two Pianos: III. Moderato assai
  type: AudioObject
  additional property: Tempo (BPM)
    type: PropertyValue
    value: 129.867
  additional property: Musical Key
    type: PropertyValue
    value: 0
  additional property: Mode (Major/Minor)
    type: PropertyValue
    value: 1
  additional property: Time Signature
    type: PropertyValue
    value: 4
  additional property: Danceability
    type: PropertyValue
    value: 0.342
  additional property: Energy
    type: PropertyValue
    value: 0.149
  additional property: Speechiness
    type: PropertyValue
    value: 0.033
  additional property: Acousticness
    type: PropertyValue
    value: 0.992
  additional property: Instrumentalness
    type: PropertyValue
    value: 0.904
  additional property: Liveness
    type: PropertyValue
    value: 0.09
  additional property: Valence (Positivity)
    type: PropertyValue
    value: 0.088
  additional property: Loudness (dB)
    type: PropertyValue
    value: -28.118
  additional property: Key Name
    type: PropertyValue
    value: C
  additional property: Mode Name
    type: PropertyValue
    value: Major

Sonata for Two Pianos: I. Allegro aperto, ma pesante
type: MusicRecording
duration: PT3M3S
duration ms: 183600
explicit: false
by artist: Willem Pijper
by artist: Lucas Jussen
by artist: Arthur Jussen
in album: Dutch Masters
  type: MusicAlbum
  date published: 2022-04-29
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6e14737bbd72524bb22ea85f370f7cf8be639b9bb1efa6dcaaa7f10732d28e53. Chain 2 (Bitcoin): anchored in block 960105 (2026-07-29T12:35:17Z), 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/NLK4J2200001.
  date published: 2026-07-29T12:35:17Z
audio: Sonata for Two Pianos: I. Allegro aperto, ma pesante
  type: AudioObject
  additional property: Tempo (BPM)
    type: PropertyValue
    value: 111.748
  additional property: Musical Key
    type: PropertyValue
    value: 4
  additional property: Mode (Major/Minor)
    type: PropertyValue
    value: 0
  additional property: Time Signature
    type: PropertyValue
    value: 5
  additional property: Danceability
    type: PropertyValue
    value: 0.423
  additional property: Energy
    type: PropertyValue
    value: 0.237
  additional property: Speechiness
    type: PropertyValue
    value: 0.032
  additional property: Acousticness
    type: PropertyValue
    value: 0.993
  additional property: Instrumentalness
    type: PropertyValue
    value: 0.822
  additional property: Liveness
    type: PropertyValue
    value: 0.165
  additional property: Valence (Positivity)
    type: PropertyValue
    value: 0.229
  additional property: Loudness (dB)
    type: PropertyValue
    value: -27.572
  additional property: Key Name
    type: PropertyValue
    value: E
  additional property: Mode Name
    type: PropertyValue
    value: Minor
isrc code: NLK4J2200001
additional property: CopyrightID
additional property: ProofProfileEvidenceStatus
  type: PropertyValue
  value: verified-cc-db-prod
additional property: TokenDeploymentConfirmed
  type: PropertyValue
  value: true
additional property: ContentHash
additional property: BitcoinBlock
  type: PropertyValue
  value: 960105
additional property: BitcoinTime
  type: PropertyValue
  value: 2026-07-29T12:35:17+00:00
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLK4J2200001
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 960105
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/960105
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-07-29T12:35:17+00:00
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