forked from
anil.recoil.org/monopam-myspace
My aggregated monorepo of OCaml code, automaintained
Add Zstd decompression to browser backend via fzstd.js
- tessera_zarr_jsoo: register "zstd" codec using fzstd.decompress
(Uint8Array → Uint8Array), bridged to OCaml strings
- Notebook setup: load fzstd@0.1.1 via importScripts before TF.js
- Blosc.decode handles the full pipeline: parse header → extract
compressed payload → fzstd decompress → bitshuffle unshuffle
- Fixes "compressed frame but no decompressor provided" error
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
+24
-4
+5
-3
site/notebooks/interactive_map_zarr.mld
+5
-3
site/notebooks/interactive_map_zarr.mld
···
14
14
#require "tessera-tfjs";;
15
15
#require "js_top_worker-widget-leaflet";;
16
16
Widget_leaflet.register ();;
17
-
(* Load TensorFlow.js *)
17
+
(* Load TensorFlow.js and fzstd (Zstd decompressor) *)
18
18
let () =
19
19
let open Js_of_ocaml in
20
-
Js.Unsafe.fun_call
20
+
let import url = Js.Unsafe.fun_call
21
21
(Js.Unsafe.get Js.Unsafe.global (Js.string "importScripts"))
22
-
[| Js.Unsafe.inject (Js.string "https://cdn.jsdelivr.net/npm/@tensorflow/tfjs@4/dist/tf.min.js") |]
22
+
[| Js.Unsafe.inject (Js.string url) |] in
23
+
import "https://cdn.jsdelivr.net/npm/fzstd@0.1.1/umd/index.js";
24
+
import "https://cdn.jsdelivr.net/npm/@tensorflow/tfjs@4/dist/tf.min.js"
23
25
]}
24
26
25
27
{1 Reactive pipeline}
+19
-1
tessera-zarr-jsoo/lib/tessera_zarr_jsoo.ml
+19
-1
tessera-zarr-jsoo/lib/tessera_zarr_jsoo.ml
···
53
53
| code ->
54
54
failwith (Printf.sprintf "HTTP %d fetching %s" code url)
55
55
56
-
let codecs _name = None
56
+
(* Zstd decompressor via fzstd.js (must be loaded via importScripts).
57
+
fzstd.decompress takes a Uint8Array and returns a Uint8Array. *)
58
+
let zstd_decompress data =
59
+
let fzstd = Js.Unsafe.global##.fzstd in
60
+
if not (Js.Optdef.test fzstd) then
61
+
failwith "fzstd not loaded. Add importScripts for fzstd in setup cell.";
62
+
(* Convert OCaml string → Uint8Array *)
63
+
let input = Typed_array.Bytes.to_uint8Array (Bytes.of_string data) in
64
+
(* Call fzstd.decompress(uint8array) → uint8array *)
65
+
let output : Typed_array.uint8Array Js.t =
66
+
Js.Unsafe.meth_call fzstd "decompress"
67
+
[| Js.Unsafe.inject input |] in
68
+
(* Convert Uint8Array → OCaml string via ArrayBuffer *)
69
+
Typed_array.String.of_uint8Array output
70
+
71
+
let codecs name =
72
+
match name with
73
+
| "zstd" -> Some zstd_decompress
74
+
| _ -> None
57
75
58
76
let open_store ?(base_url = "https://dl2.geotessera.org/zarr/v1")
59
77
?(year = 2024) () =