134ccb70f3
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67 lines
1.8 KiB
Go
67 lines
1.8 KiB
Go
package audio
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import (
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"context"
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"encoding/base64"
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"encoding/json"
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"fmt"
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"io"
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"net/http"
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"time"
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)
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// opusJSON 是 Django 预转码上传的 Opus JSON 文件结构。
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type opusJSON struct {
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SampleRate int `json:"sample_rate"`
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Channels int `json:"channels"`
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FrameDurationMs int `json:"frame_duration_ms"`
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Frames []string `json:"frames"` // base64 编码的 Opus 帧
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}
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// FetchOpusFrames 从 OSS 下载预转码的 Opus JSON 文件，解析为原始帧列表。
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// 跳过 ffmpeg 实时转码，大幅降低 CPU 消耗和首帧延迟。
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func FetchOpusFrames(ctx context.Context, opusURL string) ([][]byte, error) {
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httpCtx, cancel := context.WithTimeout(ctx, 60*time.Second)
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defer cancel()
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req, err := http.NewRequestWithContext(httpCtx, http.MethodGet, opusURL, nil)
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if err != nil {
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return nil, fmt.Errorf("audio: build opus request: %w", err)
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}
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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return nil, fmt.Errorf("audio: download opus json: %w", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("audio: opus json status %d", resp.StatusCode)
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}
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body, err := io.ReadAll(io.LimitReader(resp.Body, 50*1024*1024)) // 50MB 上限
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if err != nil {
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return nil, fmt.Errorf("audio: read opus json: %w", err)
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}
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var data opusJSON
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if err := json.Unmarshal(body, &data); err != nil {
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return nil, fmt.Errorf("audio: parse opus json: %w", err)
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}
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if len(data.Frames) == 0 {
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return nil, fmt.Errorf("audio: opus json has no frames")
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}
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frames := make([][]byte, 0, len(data.Frames))
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for i, b64 := range data.Frames {
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raw, err := base64.StdEncoding.DecodeString(b64)
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if err != nil {
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return nil, fmt.Errorf("audio: decode frame %d: %w", i, err)
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}
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frames = append(frames, raw)
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}
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return frames, nil
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}
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