reuse context-aware video read

internal/source/source.go

@@ -102,31 +102,7 @@ func (s *Source) Close() error {
 }
 
 func (s *Source) Next(timeout time.Duration) (Frame, error) {
-	for {
+	return s.NextCtx(context.Background(), timeout)
-		g, err := s.reader.GetGrain(s.idx, timeout)
-		switch {
-		case err == nil:
-			f := Frame{
-				Index:   g.Index,
-				Width:   s.width,
-				Height:  s.height,
-				Stride:  s.stride,
-				Size:    g.GrainSize,
-				Invalid: g.Invalid(),
-				Payload: g.Payload,
-			}
-			s.idx++
-			return f, nil
-		case errors.Is(err, mxl.ErrTimeout):
-			s.idx = mxl.CurrentIndex(s.rate)
-		case errors.Is(err, mxl.ErrOutOfRangeEarly):
-			time.Sleep(10 * time.Millisecond)
-		case errors.Is(err, mxl.ErrOutOfRangeLate):
-			s.idx = mxl.CurrentIndex(s.rate)
-		default:
-			return Frame{}, fmt.Errorf("GetGrain: %w", err)
-		}
-	}
 }
 
 func (s *Source) NextCtx(ctx context.Context, timeout time.Duration) (Frame, error) {