1 files changed, 92 insertions, 0 deletions
diff --git a/web/script/player/track.ts b/web/script/player/track.ts
new file mode 100644
index 0000000..b089932
--- /dev/null
+++ b/web/script/player/track.ts
@@ -0,0 +1,92 @@
+import { OVar } from "../jshelper/mod.ts";
+import { JhlsTrack, TimeRange } from "./jhls.d.ts";
+import { BufferRange } from "./player.ts";
+
+const TARGET_BUFFER_DURATION = 15
+const MIN_BUFFER_DURATION = 1
+
+export interface AppendRange extends TimeRange { buf: ArrayBuffer, index: number, cb: () => void }
+export class PlayerTrack {
+    private source_buffer: SourceBuffer
+    private current_load?: AppendRange
+    private loading = new Set<number>()
+    public buffered = new OVar<BufferRange[]>([])
+    private append_queue: AppendRange[] = []
+    constructor(media_source: MediaSource, private node_id: string, private track_index: number, private metadata: JhlsTrack) {
+        this.source_buffer = media_source.addSourceBuffer("video/webm")
+        this.source_buffer.mode = "segments"
+        this.source_buffer.addEventListener("updateend", () => {
+            if (this.current_load) {
+                this.current_load.cb()
+                this.loading.delete(this.current_load.index)
+                this.current_load = undefined
+            }
+            this.update_buf_ranges()
+            this.tick_append()
+        })
+        this.source_buffer.addEventListener("error", e => {
+            console.error("sourcebuffer error", e);
+        })
+    }
+
+    update_buf_ranges() {
+        const ranges: BufferRange[] = []
+        for (let i = 0; i < this.source_buffer.buffered.length; i++) {
+            ranges.push({
+                start: this.source_buffer.buffered.start(i),
+                end: this.source_buffer.buffered.end(i),
+                status: "buffered"
+            })
+        }
+        for (const r of this.loading) {
+            ranges.push({ ...this.metadata.segments[r], status: "loading" })
+        }
+        this.buffered.value = ranges
+    }
+
+    async update(target: number) {
+        this.update_buf_ranges() // TODO required?
+
+        const blocking = []
+        for (let i = 0; i < this.metadata.segments.length; i++) {
+            const seg = this.metadata.segments[i];
+            if (seg.end < target) continue
+            if (seg.start >= target + TARGET_BUFFER_DURATION) break
+            if (!this.check_buf_collision(seg.start, seg.end)) continue
+            if (seg.start <= target + MIN_BUFFER_DURATION)
+                blocking.push(this.load(i))
+            else
+                this.load(i)
+        }
+        await Promise.all(blocking)
+    }
+    check_buf_collision(start: number, end: number) {
+        const EPSILON = 0.01
+        for (const r of this.buffered.value)
+            if (r.end - EPSILON > start && r.start < end - EPSILON)
+                return false
+        return true
+    }
+
+    async load(index: number) {
+        this.loading.add(index)
+        const res = await fetch(`/n/${encodeURIComponent(this.node_id)}/stream?format=hlsseg&tracks=${this.track_index}&index=${index}`)
+        if (!res.ok) throw new Error(`segment fail i=${index} t=${this.track_index}`);
+        const buf = await res.arrayBuffer()
+
+        await new Promise<void>(cb => {
+            this.append_queue.push({ buf, ...this.metadata.segments[index], index, cb })
+            this.tick_append()
+        })
+    }
+    tick_append() {
+        if (this.source_buffer.updating) return
+        if (this.append_queue.length) {
+            const seg = this.append_queue[0];
+            this.source_buffer.timestampOffset = seg.start
+            this.source_buffer.appendBuffer(seg.buf);
+            this.append_queue.splice(0, 1)
+            this.current_load = seg
+        }
+    }
+}
+\ No newline at end of file